Q&A / Tech

Ask Away! with Jeff Smith: Troubleshooting and Tuning a FAST EZ-EFI Fuel Injection System

I recently bought an EZ-EFI throttle body fuel injection system from FAST for my ’70 Buick Skylark. I installed it according to the instructions and it started and ran pretty good for the first few days. I’ve noticed now that the engine runs very rich and it’s starting to load up the spark plugs. I’ve not changed any of the settings yet it runs a lot richer than before. My idle air-fuel ratio is 13.0, the cruise setting is 13.5, and wide open throttle is 12.5. I don’t understand why the engine seems to run much richer than these settings. You have any ideas?



This is an EZ-EFI throttle body on a big-block Chevy we did a couple of years ago that worked out very well. Attending to the details will make a big difference in how the system works.

Jeff Smith: We’ve installed several of these new-generation, self-learning fuel injection systems and they seem to work very well. But there are a couple of areas where it is essential that the initial installation be performed properly and then attention to details can make all the difference. Let’s see if we can focus in on your problem.

The first thing to emphasize is that the main power and ground wires are in fact connected directly to the battery. All EFI systems operate on electrical signals from sensors that normally operate on a 0-5-volt scale. This leaves very little room for error with regard to proper grounds. So it is essential that the main power and ground leads go directly to the battery. This allows the battery also to operate like a giant voltage spike suppressor which allows the electronic side of the system to operate normally. Don’t be afraid to lengthen either or both power and ground leads if that what it takes to plumb them directly to the battery.

The next item to try is to run back through the initial calibration process again. This essentially purges the computer’s memory of the previous tuning changes. This means starting with engine displacement, idle rpm, rev limit, fuel pressure, and resetting the throttle position sensor (TPS) calibration. Then set your idle, cruise, and WOT settings the same as before. Once all this is complete, the engine should run as it did when you first installed the system. Drive the car for a couple of days and make sure to shut the engine off and restart it several times during the test. You may notice that the engine begins to run rich again after several cycles of running and then shutting the engine off. If the over-rich condition returns, I think what you may be experiencing is a very common problem where there is a leak in the exhaust system that is causing the over-rich air-fuel ratio problem.

If you’ve ever driven a car with an exhaust leak, you can often hear a very audible tick-tick-tick from the exhaust. The tick you hear is the result of an exhaust pressure spike that travels down the exhaust pipe, finally exiting after the muffler. When that pressure spike hits the atmosphere, it sends a reverse or low-pressure pulse back up the pipe and back to the engine. This low-pressure spike will pull in outside air as it passes through the leak area. Think of it like a siphon pulling fresh air in from the outside. Unfortunately, this can cause problems with a self-learning EFI system.

All of the self-adapting EFI systems use a wide-band oxygen sensor placed roughly at the header collector, downstream in the exhaust system. The sensor reads the exhaust gas and the engine control unit – the computer (ECU) uses the information as feedback to the tune. As their name implies, these wide-band sensors (WBOS) operate over a much wider area of air-fuel ratio from very rich at 10:1 to very lean at 20:1. All WBOS operate the same way. They do not actually measure the ratio of air to fuel. Instead, they are calibrated to sense the amount of free oxygen in the exhaust system. The ideally-balanced chemical air and fuel ratio for any fuel is called the stoichiometric ratio. For gasoline, this ratio is 14.7:1. With lean air-fuel ratios such as 15.8:1, there is more free oxygen in the exhaust because there is minimal fuel to complete combustion. This is called an excess-air ratio. An air-fuel ratio of 12:1 for example would be considered an excess-fuel ratio and contain very little free oxygen because there is more fuel available to use more air to combust the fuel.

The reason it’s important to know how a WBOS works is because there are several conditions that can fool an oxygen sensor into thinking that the engine is running lean. The first situation is actual misfire. Often, an engine might create a misfire that you may not necessarily feel as a hesitation. This happens quite often under high load at WOT. When this misfire occurs, that unburned fuel and free oxygen travel out the exhaust where the WBOS reads the free oxygen. This is then interpreted that the engine is running too lean and needs more fuel.

If, as may be the case with your car, you either have an engine misfire or – more likely – a leak in the exhaust system, this higher oxygen content in the exhaust will quickly fool the WBOS into reporting to the ECU that the engine is running lean. This adds fuel to the engine. What makes matters worse is that most (if not all) self-learning EFI systems store the new air-fuel ratio tune to the ECU when the engine is shut down. Then the process starts all over again because the leak in the exhaust system is still fooling the WBOS, each time the engine is operated and then shut down, the new, richer self-learning table is added to the existing tune. This is the downward spiral that makes the engine run richer every time it is started and run.

So it could be the solution to your problem is to check the exhaust system very carefully. Two logical places for air to enter the exhaust system is the gasket between the header and the head and the other at the collector flange where there is often a gasket that can easily allow fresh air into the exhaust. This can occur even if there is no audible tick or leak in the system. If the header gasket shows black exhaust tracks past the gasket, it’s likely that it is also allowing outside air into the exhaust. Another possible leak path is the WBOS mounting bung itself. Make sure that this fitting is fully welded into place with no pinholes that could allow air very near the WBOS itself. Another possible leak path could be any place where two exhaust pipes are welded together. This is a very common place for leaks to occur. Look for these holes at the top of the pipe where it is most difficult to weld when the pipes are in the car.

A great way to check for exhaust leaks is to pump smoke into the system. There are several commercial smoke generators on the market designed for this kind of testing, but we have also seen some ingenious home-built smoke leak detectors built with liter soda bottles that can do the job. Eliminating even a very minor leak or crack in an exhaust system will make a huge difference in improving the performance of your fuel injection system.

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  1. I solved all my Fast EZ EFI problems by removing the whole thing and tossing it in the trash. Fast could use a tech rep like you, because they are no help at all.

    • cary fowler says:


    • barry dyer says:

      Go get it and send it to me ! I have one on a Corvette and it’s been there for years with no problems. Damn good unit I have two fitech and they gave me some trouble. They are harder to get running and staying in tune !

    • No doubt, I’ve tried everything anyone could suggest.
      I can smoke that fast fuels ass with a stock quadrajet!!
      Getting a new holley, throwing that whole setup in the dumpster!!

    • My 72 351 had a bad header leak and now is fixed and I have only ran it twice since repair and I smell fuel at idle do I need to run it some more or reset this system it runs 13.2 air fuel mixture and how do I know if I have the right plugs

  2. JACK DAVIS says:

    I have a 1946 Chevy PU with a 383 stoker engine from Summit. FAST ez injection installed and from the get go never ran right. Come to find out the computer went belly up and whatever was programmed in the next day was back to factory. New computer installed and for a few days was good. No back to the old problems, stalls immediately after starting. Time and time again. Worst when cold. Sometimes I wonder if I will get back home if I am out and about. No fun.

  3. Ron rolens says:

    Fast tech support sucks they know nothing about what they or selling my 10 year old son knows more then they do

  4. I agree the fast tech team sucks, absolutely worthless , their own parts they sold me to upgrade my distributor hei factory to one of their 4 pin modules that’s suppose to give a clean tach signal. Well what do you know the car wouldn’t even start. It was running very rich I upgraded to a peritronix cap and high voltage Coil and then recapped plugs to 55 and then ran car back through the programming stage and it’s been no issues since . Actuall running very good

  5. Bruce Horton says:

    I have the ez efi 2.0 on my 96 Roadmaster wagon with a pretty healthy 455, I absolutely hate it , it will show 15.9 air/ fuel ratio and be loading up so bad your eyes water, And hardly ever starts without 30 seconds of cranking, backfiring, cranking. And I’m getting 5 mpg less than when I was running my 1000 Holley with 88 jets square. Worst money I have ever spent. Never Again.

  6. Rona;ld Nekula says:

    I too am having issues with my EZ 2.0 system. Out of the box it ran great. I don’t drive it much an might have put 200 miles on it in a year and a half. First time I had issues, tech gave me the same run around they give everyone. I rewired and replaced. After reading several threads I changed the MAP sensor and corrected the problem. I have driven it maybe 50 miles since that time and is giving me fits again. Tech support has been non existent for the past week. Thing runs but idles funky and studders when accelerating. Not sure where to go from here because there are no errors showing this time. All I know to do is start replacing sensors. Is there anyone with good knowledge on troubleshooting this system?.

    • Guy Bennett says:

      I had similar issues with running rich and studdering on acceleration. Was also throwing 02 censor code. I was so frustrated with it I handed it off to a tech that tried everything and just because he had tried everything else he switched out the plug wires and put later model wires off a fuel injected engine. They have a coating that stops the rf noise that interfere with the system. Sounds crazy but it worked. We chased it for the better part of a year. I havent run down the road yet because of the weather in Ohio but it runs smooth idles nice and no more codes and the green learning light comes on which we couldn’t get before. All the parameters are correcting as they should. Try it . It’s an inexpensive option that might just work.
      Good luck!

    • HI Jeff
      My name is charlie, I have a Hilborn 8 stack F.I.
      Unit on a 462 chevy BB. Having starter kick back
      issues. I have contacted Hilborn and Fast. I need
      more input in order to proceed with a remedy to my problem.
      Best Regards,

  7. HI have you had it out after replacing the wires? If so how is it running?

  8. Dave Vandehei says:

    i feel like i was misleadright from the minute i read the add. I called fast and ask if it would work on my 550 hp pontiac 428 . They said it would. I wish i remembered to write down the guys name when i called six months later and the first thing they said was that system wont work on that. i tried everything from credit twards one that will work to ill see you in court. they hung up on me

  9. Daniel Wilson says:

    I’ve read some very interesting topics that On All Cylinders has presented for the readers enjoyment but never quite understood why nobody took the time to comment. Just look at all of the negative comments from so many VERY unsatisfied owners of the FAST EFI System. WOW !!!

    I’m a big fan of the truth. Especially if it concerns a product that I have been seriously considering purchasing for my extensively modified 351 Cleveland engine project. I’m sure that many are satisfied with this EFI system but considering the total number of people that read this forum and the surprising number of negative comments, my old school Holley is working to my total satisfaction.

    From a technical standpoint, I can’t justify the cost of an EFI throttle body injection system that introduces fuel into an engine at the exact same location as a carburetor does. While the fuel might be better atomized and metered to suit the engines requirements at any given time, it is still subjected to the well known inconsistencies and distribution problems associated with intake manifold designs. Most intake designs are at best a compromise between low and high rpm performance. Maybe with one exception but everyone can’t run a tunnel ram on the street.

    Since fuel delivered by means of throttle body injection or carburetors is at the mercy of plenum and runner compromise, a better way would be to switch to one of the newer intake manifolds available with a boss cast into each individual runner at the heads intake port. The boss can be tapped for nitrous oxide injection but for my money, fuel injectors installed at each port will provided more consistent and reliable results when retrofitting a Classic V-8 for improved performance with the bonus of greater efficiency by using a modern EFI system. All aftermarket EFI systems are NOT created equal but they ARE all equally expensive. It’s best to do a little research before spending thousand$. You don’t want to end up crying on a blog about a product that sucks and the big name manufacturer greets your calls by hanging up. And the beat goes on…..

    • Amen, you are so right!! I’ve haved/have nothing but problems from day one since installing this EZ 1.0 w/new hand held ;i.e. new EFI Fuel tank, new 3/8 metal feed and return fuel lines plus new MSD 6A. I been three years and no smiles here!!!

  10. Robert Dixon says:

    I just bought the EZEFI. Still waiting for delivery. For the last couple of days I’ve been reading up on it( should’ve done that first) and it doesn’t sound like it’s going to work for me. The only thing the salesman said is as long as you have min 9-10 inches of vac it will work. That’s where I’m at so I figured it would be ok. Since then I’ve read it doesn’t work well with manual transmissions or any kind of road racing. Or cams that are cut on a 110 lobe separation. I fall in all those categories. I hate to return it without even trying it but if m to believe what everyone says it just won’t work on my car.
    I’m running a .030 over 455(462), 10.7:1CR, lightly ported Edelbrock RPM heads, a 232/241@.050/110 LSA Lunati Voodoo cam and a M20 Muncie 4speed trans.

    What’s your opinion, will it work?


    • Jeff Smith says:

      Robert – I will answer your question shortly:

      Ask Away! with Jeff Smith: Will My New EFI System Work With My Setup?

      • James Buelt says:

        I have recently installed the EZ efi fast system on a 66 Chevelle the presquirt works the car will run until that fuel is gone then it dies.the fuel pump triggers on and goes to 43 psi when I turn the key then it drops. the pump does not turn back on until I cycle the key after waiting a bit?

      • Should you use the stock ignition module with the new FAST EFI system?

    • jethro west says:

      dor yourself a favor………….do not install it! send it back now! I have a brand new X2 890 cranking amp battery………I get an error code, Battery….All connections are tight and new. I am pulling the piece of crap off my fj40 sbc and going with a carb. I have an MSD 8360. It had a vaccum advance…..I had to put a vaccum advance lockout kit on it……..It has run good for a year! I also installed an MSD on it ……All by the book………DONT BUY THIS POS!

    • I have been running this system on my .030 over 455 with edelbrock heads with a larger Lunati sold lift cam and 10.5:1 compression. The system has worked great for the 4 years it’s been on my car.
      Was a little hard at first to set up but works great.
      Set your idle up around 850 rpm IAC 15-20 and lean it out at idle with the hand held to compensate for the over lap in the cam.you may also have to play with your accel fuel,only move one point at a time it makes a big difference.

      • Its normal not kick on every time key kicks on sound like u got bad pump or regulator I had the issue done same as you said
        Thats issu setup hard but after you get it there great

    • I have to say that I am completely done with this junk system. A year of my car not running. Tech support is absolutely ridiculous. The only reason I started getting return emails was by threatening them. First it was a bad RPM module, then I replaced my whole ignition system, then it was insufficient voltage to the handheld, then it was add this switch and relay into the system and it will work still nothing, then it all works again and drops the RPM signal again. And now the factory fuel rail is leaking fuel. Here is the funny part, the car ran after each one of these steps for exactly one day. The problems are all over the place with the system. I just this week emailed the tech support guy and told him to come out and get the system running himself or refund me all my costs plus the cost to convert back to carbs. I also informed him I would tell my story on every forum or site I could. So there it is. Return your system before you do anything and stick with carbs from a reputable company because FAST is junk.

    • Dear Robert I am using one on 383 with 234/ 238 @ .50 and have no problems. Just remember to tune correctly

    • Kiss that cam lope goodbye,
      High idle, no better fuel mileage, if u can trade all that for a fast start-up, good luck!!
      A good holley will always smoke that Efi’s ass!!

  11. Need help with INJ DUTY error code on EZ-EFI, Car has been running but it will lose it mind in 24 hours. Fuel Pressure will not stay set at 43 psi it will jump to 60 psi after setting all night . Ready to put a Holley on it and be done.

  12. I was going to buy a FI Tec till a buddy had problems with his, so I figured I’d go with the FAST easy EFI 2.0 Well that was a big mistake. I’ve gone over and over my engine and exhaust to see if there is any leaks. I have both power and ground going to the battery. And today I’ve leaned it out beyond the suggested targets and I still watched my gas gauge drop. By the way I’m getting 25.9 liters per 100kmh. I shit you not from empty my tank holds 53 liters and I get 204 km out of a tank. Not just once but three times now. I can’t even give this paper wieght away. Oh and it’s just a normal 350 with a RV cam in a first gen toyota 4runner with a 700r4 and most are highway km.

  13. Using an EZ-EFI version 1 here since 2012 on my Cobra replica with a port injected SBF and T5. The performance has been perfect. Sorry to hear about all your woes.

  14. It seems I have some of the same problems others have with 9-10″ of vacumb being insufficient, my cam is 240-246 duration in a sbc 406, the engine is cold natured fouling plugs, then stalling when I put the car in gear, even warm idle issues persist along with hard starting at any temp, I also didn’t research the product before purchasing it. OOPS, now the realist in me surfaces. Why did I get better diagnostic info on it from threads online than comps tech dept? How much driving do i need to do before learning is complete? Why do the sales people not communicate the necessary info to their customers?(commission?). Why not put the ability to tune values in such a expensive product? If it wont work, who’s will? some threads say no self learning EFI will work with these large overlap cams. The carb only had warm up issues and sensitivity to our poor fuel. Does the carb need to go back on?

    • Raymond Bogenschutz says:

      Update!!! I returned the ECM and upgraded to the sportsman, then purchased a couple of sets of spark plugs. ( you’ll need them) Here we go. I didn’t really want to learn how to tune an EFI system but it’s really a must for my application. Tuning the VE table is not too challenging. I did it best with my 20 year old nephew on the laptop as I drove and gave him values to enter based on current ones in the table vs what the engine seemed to want.To put it in a nutshell the biggest challenge is to figure out where to get the fuel enrichment and how much. I spent at least 20 to 40 hours just driving around the block to see How each parameter affected how engine response , and burned 60 or so gallons of fuel. I also discovered how good the fast ECM is at controlling spark in conjunction with my msd digital 6 ign system. (Try it!) I still have some tuning to do, however I now fully understand how some will never return to a carb again! The car had that count em down idle ( cool at a Cruze in but a pain on Powertour type trips) and it idled differently with each fill up. Now the cam seems tamed and the idle is better than ever. Perhaps the challenge with converting to EFI is how to ask questions about something you know nothing about. There is much more to the story, however I’m glad I made the dive in the car is a joy to drive and I find I’ll drive it when in the past it was (not worth the hassle) and the knowledge gained me additional respect from my fellow gear heads.

    • 300to 500 mile or so

  15. JEFF DESIMONE says:


  16. Barry Davis says:

    ecu not respornding and fuel pump not working

  17. David Parker says:

    Gooodd grrriefff. I just saw a video of how simple and effective this system is (intended to be) on upgrading your old V8 pushrod cast iron block, and I thought, there’s something to possibly think about in the future to get rid of carburetor problems and increase performance and gas mileage. Wow!

    O2 sensor, high-pressure fuel pump, plus a $2500 price tag for the system, you would think this would be straightforward and problem free once installed. Evidently this is not the case. Sounds like someone might be better off putting up with a few carburetor problems and repetitive jet changes (which at some point would end). Is there a competing manufacturer of these systems that is a better product? How does the factory do it, BTW?

  18. Harald Thorsen says:

    I have a Fast 2.0 system that run ok yesterday, today the car dont start. It have 47psi on the fuel line,cheked everything with the fuel line and here everything is ok.
    The problem is that the injectors dont deliver fuel…..
    any suggestions ?

    • Jeff Smith says:

      These are difficult items to diagnose without first-hand knowledge – but the first suggestion would be to turn on the system and pull up the page that shows rpm and monitor rpm as the starter cranks. You should see an rpm signal. If there is no rpm signal – the unit will not deliver fuel. Start with this. Also check the ignition to make sure there is not a fault with the ignition – even if the FAST system is not controlling spark. If nothing else, try completely re-configuring the system as if it were brand new. See if one of these items miight help get it running. But don’t ignore the basics and don’t assume that the FAST system is at fault. I had an EFI engine fail to run only to discover the tach wire had grounded out – killing the ignition system! But for a day or so I blamed the EFI system and then looked stupid when I found the real problem…this happens more often than you would think.

    • Look at the map sensor if it is bad or funky reading it will shut off injector pulse. I learned this the hard was after purchasing another module. Put a new map on it and everything has been better since

  19. Rick Thompson says:

    Hello Mr. Smith:
    Have a 98 suburban with a new/old school 400 small block. Dart Block, Edelbrock performer heads, Edelbrock Performer Intake, Fast EZ -1 fuel injection. Everything runs great until I go up long incline, RPM between 1600 RPM and 1800 RPM, 46 MPH and 52MPH, It cuts out or runs real rough. Press on the pedal a little goes away, let off pedal a little goes away. Runs great above, and below. Transmission is a rebuilt 4L80e. with better clutches and shift kit, 1800 Torque converter etc. Fuel Pump is a new GM in tank, works good in low or high acceleration.
    My Friend who is real good with the FAST systems has not yet figured it out.
    Did it before the Transmission was built and still now after. Still in the same spot.
    The AFP is 13.5.

    • Jeff Smith says:

      It sounds like the engine is lean. Granted the AFR you said was 13.5:! which should be sufficient to allow it to accelerate normally, but every engine is different and they often need more fuel than you might think. I would try richening the part-throttle fuel to 13.0:1. Unfortunately, this will require the engine to run richer when it does not need to, but this is a result of the “big picture” adjustments that these throttle body systems are set up with. If that richer adjustments works, then you can lean it back a tenth or two until it stumbles again. Then its’ just a matter of deciding how much you’re willing to compromise with the overall mixture.

  20. Car guys need more sites where honest information like this can be shared! Too many of the magazines and articles are just shills for these less than competent manufacturers. And the large on-line mail order houses are not much better as they all hype the products to get you to buy something, anything, just to make a sale knowing that the return hassle and cost will likely discourage that from happening.

    • OnAllCylinders Staff says:

      Thanks Gary, we appreciate the kind words!

      • brent Denton says:

        I have one of the first generation EZ EFI system that came out, that being said it sat on shelf for 5 years until car build was ready. After many attempts to get system running and flooding out my engine I have it figured out. My engine is an original 454 LS7 12.1 with big roller cam and dual plain intake factory snow flake style. I only have 7 inches of vacume at idle. I finally replaced the TPS sensor with a none china model from NAPA as it was bad right out of the box! not the only person to experience this it seems. Now to trick the system to learn with out flooding the engine on initial startup due to low vacume. raise your idle to 2200 rpms and let the system fully warm up so it will start learning, then slowly bring the idle down and calibrate it each time until you reach your desired idle rpm for the final calibration. pain in the a*** but works, my system has been great ever since. car runs mid 10″s at track and daily driven. just my two cents

    • I couldn’t agree more. The articles in our favorite magazines are nothing more than paid advertising for the big manufacturers. Ive been fighting with my EZ 2.0 EFI for years. Tried everything, even taking to someone else. Same story! This unit and what it advertises is a complete scam. Everywhere you look on the internet people are complaining about this product. It amazing there isn’t some sort of lawsuit! I’ve previously had great experience with Comp Cams, but I’ll never buy their and affiliated products again.

  21. Joe Wilkens says:

    Hi Jeff. I’m having a problem with fuel pressure dropping dramatically after I drive my BBC equipped with a Fast 2.0 for 30-45 minuets. It’s left me on the roadside many times. All I have to do is wait it out and I can start up and run great… for a while. Fast tech guys deny a pump problem but I’m skeptical. Planning to change the pump and filter and look for an obstruction in the tank when I have it apart.What do you think? Thanks!

    • Jeff Smith says:

      I would need more information about how your fuel pump is mounted. Is it an internally mounted pump? I’ve run into this before – usually due to an externally mounted pump. If the pump is external and is mounted high above the fuel tank – this can cause the pump and fuel to run hotter. After 30-45 minutes and a low fuel level, the fuel vapor locks on the inlet side because the fuel is hot and turns to vapor – which is what it should do, but only after it is in the engine. Another potential problem could be a restricted inlet side if the pump is internally mounted. It could also be excessive voltage drop (resistance) in the power feed to the pump. This is easy to diagnose but should not be overlooked. As heat builds this also increases resistance.

      • Joe Wilkens says:

        The pump is inside the tank. I’ve tapped into the power wire going to the pump and brought that wire inside the car and attached to a meter. Getting only 10-11 volts during operation but voltage goes up when fuel pressure drops.

        • Jeff Smith says:

          If your test is accurate, you have found your problem. Ten to 11 volts will not allow your pump to produce anywhere near its intended volume and pressure. The EZ 2.0 uses a fuel pump relay to power the fuel pump. Check voltage at the relay with the pump running. If the voltage is near 14 volts, then the voltage drop is after the relay. If it is low going into the relay – the problem is upstream. It could be you are using too small a electrical feed wire to the pump. Smaller wires produce more resistance. You should have a minimum of 13 volts to the pump at all times when the engine is running.

          • Joe Wilkens says:

            After removal of the tank and changing out the pump and filter I seem to have corrected my stalling malfunction. It appears that the pump was getting weak and not doing it’s job! Thanks again for your input!

  22. we have installed a fast ez on a stock 304 jeep cj and it idles great not running rich no codes and all adjustments were done and double checked the problem is a hard stumble on acceleration like a flat spot any clue

    • .had the same problem with my 327 sbc.would stumble off the line and die. had to throttle it easy. went into the master, selected enrichment fuel, then accel fuel and decreased the fuel. after a couple of decreases I found it performed better at negative 3.still learning to make adjustments. i am old school but the throttle response of this throttle body is remarkable. If I get it all set it will be great’

  23. Anthony cella says:

    hey Jeff, I bought a Chevelle back i Jan 2018 with fast 2.0 . Running great until one day it went into limp mode at first start up. Next day it wouldnt start. No codes, but I did find the msd is not powering the coil. Also the wizard only shows three settings and goes right to tps. I did change out the battery without unplugging the ecu which I was told could have fried it. Your thoughts? Thanks

  24. My boss has a 74 vett with a mild 350. About 6 months ago I installed ez 2.0. Where having 3 problems, one is long cranking, I adjusted the cranking setting and has made no difference, I’d almost say it’s not changing anything like its not working
    Once started if you wick the throttle it stumbles hard,dies half the time. I adjusted the accele setting with no change, again like its not making a change.
    The last thing is around 1,400-1,800rpm it never auto tunes. But shows 11.0-11.5 afr buy anything above that it works.
    Down the road or getting on it it runs really good

  25. was driving & just qiut, got it home & checked fuel pump, it’s good, 43 lb pressure, getting fuel to TB but will not start or run, don’t seem to be getting into TB, however it will if fuel is poured directly into TB.
    Shows no codes because can’t start it to go thru system.

  26. For what it’s worth here is my story with FAST EzEFI 1.0. I have a shop outside of Memphis, TN. The advantage I have is that most of the Tech’s at FAST live near my shop. I decided to buy a EzEFI 1.0 system to put on the 1978 K5 Blazer restoration project that we were doing. When the truck came into my shop it was running (well) the owner wanted to put fuel injection on it so they didn’t have to pump the carb to start it. After a three year complete ground up restoration came the the day to take it out for it’s shake down drive as we do with all cars. Prior to this the system was running pretty good around the shop after setting up the system. We had to disconnect the battery for about week prior to the shake down drive. It seems that once we re-connected the battery that is when everything went wrong. It would start but would die right away. One thing to note “everything on this truck has been replaced” Everything! so there wasn’t any of this, change this, and change that!. Anyway.. after two days of calls to FAST and re-setting the computer. I insisted that someone from FAST come to my shop to look at this. The tech and tech manager came out and after an hour we were able to get it running, Although it was running poorly. We took the truck to truck nationals and while driving around it was loading up and stumbling on it’s self at near idle. It was funny FAST was at the show and they messed with it for about an hour still no better. They told me and customer that is needs to be driven for about 50 miles for it to learn what the engine needs. They also stated that a newer hand held controller would give better tuning ability. I actually paid for that since my customer has spent over $40K having us restore his truck and it runs worse than it did when he drove it into my shop. We found out that the plugs were fowled from all the fuel. Lets fast forward a month and I received a call from my customer and said “Change it back to carb!” so we spent a full day switching it back to carburetor. After putting on a new carb, it runs so smooth and starts right up. I WILL NEVER recommend FAST system to any of my customers. I have had some success with FiTech system on our shop truck and so far so good!

  27. Here is my question… i have a fuel injected , odd-fire V6 with a fast EFI system- i believe it is the 1.0 version. The car is running super rich on the right bank of cylinders only and fouling plugs…. it did not come with the hand held- so i have no way to tell about the set-up parameters, etc… I cleaned and moved the oxygen sensor as it seemed that the baffles in the lakester type headers may have been interfering with the 02 readings….. Help!!! Thanks.

  28. Greg bolton says:

    I bought a used 565 BBC with a fast xfi sportsman multi port injection, should it hold fuel pressure after the pump primes the system ? It seems to run ok, just smells really rich, never drove car just started a few times. Can you guys build a program for me ?

  29. Hi Jeff; Purchased the Fast EFI 30227 master kit in 2012; was living in NJ & it worked fine. Moved to Texas 2013 was running fine; vehicle is 1955 Chevy with 350 crate engine in 2005.
    Yesterday was going to go for a ride nice day in Texas; had hard time starting & once in ran it will not idle below 1200rpm, sounds like it is running on 2 or 3 cylinders; any Ideas?

    • Jeff Smith says:

      These are difficult to diagnose from a distance. My suggestion would be to make sure that the rest of the engine is fine before we immediately blame the EFI. This happens all the time. So you need to actually measure things like fuel pressure, make sure the ignition system is in perfect condition, has the engine suffered a failure like a blow head gasket, or perhaps something simple like all the intake manifold bolts are loose. Don’t laugh,this happens all the time – especially on engines that only run occasionally. Check everything else first to eliminate all the other possibilities. Idling very high could be a vacuum leak from a bad intake gasket. This also makes the engine hard to start. There cold also be a bad hose leading to the PSV or power brakes. Eliminate all those first and then look at the EFI.

  30. James Crandall says:

    Hey, Jeff. I have a 1977 Dodge Charger Daytona SE. It has 440 ci. w/ Indy EZ-1 street heads and single plane intake, Custom grind Comp.Cams Hyd. roller cam. Intake lift .624 Exhaust .579 Duration @ .050 Intake 236 exhaust 244. installed @ 108.0 centerline, 110 lobe separation. The engine is professionally built and dyno-tested. It made 545 ftlbs @ 5200 rpm and 575 hp @ 6400. It has a hemi 4-speed, dana 60 – 4.10 w/ 32inch m/t ET streets 3 inch SS exhaust w/ single chamber mufflers. Rick’s Tank’s in tank Areomotive 340 lph fuel pump. FAST EZ EFI 2.0 10-12 in. of vacuum. The 2.0 was run on the dyno to make those #’s after initial set up w/ a carb. It ran well when i first put it in the car but not for long. Started to run very fat and has ever since. I ordered the EFI 2.0 system in 2013 and had to wait to get it, I think I was # 54 to receive it. Dyno tests were in the end of 2014 then finished building the car in 2015. It runs so rich I have to shut it down in the garage. FAST has had the ECM, the throttle body, the regulator and I have changed every sensor, some more than twice. At idle it really loads up the plugs, i have to remove them, clean them and /or replace them every two weeks just to move the car around. Part throttle and WOT is rich but it is an animal! At idle it’s washing out the cylinders. Will an XFI sportsman and a professional tune correct this issue or am I just throwing more money away??? HELP!!!

  31. Funny,
    i want input on the FAST Intake and NX port kit package. I have a 16 Chevy SS with a Fast 102 LSxr manifold with Nitrous Express port injected system.
    The original installer crashed and burned and I won’t work with them.
    NX looked and tested the system and said the fuel flowed properly.
    When initaiting the hit, after purging the N2O valves, The engine “drops out” momentarily. and comes back. It may backfire or go full lean then come on hard.

    We are doing a complete full forge build now with a D1x and required accessories.
    Question: Is this lean or drop out condition common.
    My theory it that the small fuel jets and the void in the solenoid to jet allows for the momentary lean spike.

    Is this a condition that has been seen before? should i develop a purge to port system? it seemed to improve by tapping the throttle or activating the system just long enough to get fuel to the ports and then using the full system.
    It may be caused by a leak down in the fuel system at the solenoid but I can’t see that because the fuel is always supplied with pressure to the solenoid. I amready to start test n tune with the new engine and build.
    I am just looking for realistic suggestons on the condition I had. Not to mention that Livernois tuned this NX kit so poorly that # 7 failed in their testing and the car was passed on to me without any remedy. Very poor professionalism and workmanship.

  32. John Potsch says:

    A dual plane engine acts as 2 4 cylinder engines. The issue with these systems is that a divider in the intake plenum often blocks the map sensor reading of both banks. My friend has a 455 ( 462 ) that has a Butler top end kit. His oxygen sensor is in the left exhaust bank – The map sensor was reading the right bank. How can it self learn if its not getting map readings and oxygen sensor readings for a accurate A/F ? They should have set these throttle body systems up with programming to read at least one oxygen sensor for each bank. I guess they assume that everyone with a dual plane intake has it already notched.

  33. Jeff Smith says:

    I’ve run O2 sensors on both banks to evaluate the difference between banks and frankly, I didn’t see any difference. While it is true the dual plane operates as two four cylinders – it is not split longitudinally – but rather by firing order. So there are two cylinders on each side of the engine that are fed from one side and the same for the other – so having to run a pair of O2 sensors is not necessary nor needed. So don’t be concerned with that issue.

    • John Potsch says:

      We ordered a Torker 2 to replace the Performer RPM on his 455 in his T/A. I will let you know how it runs after the swap. I’m thinking the equal length runners will help fuel distribution. I have read on the CPG forums that the EZ EFI 2.0 does really well with a single plane. There was also a episode of engine masters where a divided dual plane just would not run right above 3500 rpm. They swapped to a single plane and it was night and day difference. Episode #2 I believe. We went with the Torker 2 because of shaker clearance issues with his hood.

  34. Kristopher Ross says:

    I’m at an absolute loss. My 72 blazer with a mid 90’s tbi engine (stock) was just in the shop for three months where they put an EZEFI complete system on. This cost me a lot of money I wasnt planning on spending, and I was diagnosed with leukemia during this ordeal. I finally took my truck back because I cant afford anymore work due to medical bills.

    Anyhow, I need help. 95% sure this whole thing is installed correctly. Starts and idles fine, but any throttle at all it sputters, pops, and has absolutely no power at all.

    Everything is new HEI, Fuel system, Tank cleaned, new sending unit. Fuel pressure is perfect, new plugs etc. No Vacum or exhaust leaks.

    Any freaking idea? I’ve done everything I could think of.

    I just want to drive this thing

    • Kristopher Ross says:

      Oh BTW, at one point the ECU and RPM module was sent back and replaced by FAST, so that has also been checked

    • John Potsch says:

      have you tried adjusting the throttle position sensor? There should be a adjustment screen that shows Throttle position percentage. You go to that screen / setting and move the throttle wide open and check screen to make sure it’s reading 100 percent when you are at WOT and 0 – 1 percent at idle.

      • Mine did same thing, had bad TPS out of box. It would constantly change and require a calibration be done. I replaced it with a NAPA high quality one and re calibrated problem solved..

  35. James D Prause says:

    I have a problem with the handheld unit. It works fine when hooked directly to the ECU, but when I use the extension cable it stops working. I thought maybe the extension cable was bad so I purchased a new one and the handheld still stops working when the extension cable is used. Screen reads: Error! No ECU connected or Incompatible device connected Please recheck connection to the EZ-EFI Fuel ECU …attempting to reconnect…

    It will momentarily reconnect and then show the same error.

  36. Well guys I guess I’m in the Club.. Have a customer with this system in their car and all I say is that it’s the cheapest p.o.s. I’ve ever come across I’m having to replace all the sensors,injectors,and every 3 months spark plugs because it keeps fauling them out … Finally got it going right now the monitor screen won’t communicate with ecu.. Order a new same thing.. How is it that a company can put out crap and still be in business?? Oh and just to let everyone else know this is a sister company of comp cams.. That should tell you something.. If you can wait 2 hours on the phone for someone to answer while the phone rings and rings.. And the people on the tech line know nothing about their product they put out or work for..

  37. Well I guess I’m in the club too. My 429 Cobra has always had some sort of issues in the five years I have had it. First my car almost burned to the ground from leaky fuel rail seals. They told me no problem and sent me two new rails with seals. I’m lucky I caught it before any fire. Then the tach module quit. Then issues with distributer and coil problems to being talked into there High Output E6 Box. The engine still has idle problems. My local Fuel Injection Shop told me there was only one fix. get rid of the FAST and go with there own system. Getting ready for the change.

  38. Starte kickback issues, fast xfi c-com ver, 1.340
    On a 462 chevy bb please reply thank you.

  39. alexander dunatov says:

    Ok…..so if fast ez efi isnt a good system, who makes a multi port retro-fit kit? I have a sbc with a holley stealth ram using Accel gen. 7 dfi. I was going to buy the ez efi kit but after reading all these bad reviews I think maybe not. Where else should I look for one!??

  40. Craig Wagoner says:

    I believe the FAST system is crap. I have one of the first 1.0 systems and it has been a pain in the a*& since it was installed. It used to cut off after driving it when I’d go to park it in the garage…wtf? I had the original coil and distributor in my 1973 Dodge Charger. The engine had been rebuilt for horse power and prior to the EFI they put a Edelbrok 4 bbl carb 650 cfm. During the initial years long troubleshooting with the people at FAST they had me send in the ECU and tested it and said all was ok. They then sent me the new color screen handheld which allowed for more settings and had better diagnostics and live data info. Looks nice but constantly loses connection to the ECU. I first had it connected to the battery for setup and they kept saying it needed to be on a switch 12v circuit. It would cause the ECU to blink too when the engine was on and even trip codes. I upgraded the old school coil to a MSD as well as the ignition to a MSD Digital 6 AL. That helped keep it running and not stalling at low speed or idle. I finally moved the handheld into the car and ran the positive to a switch 12v circuit and sometimes it works and sometimes I get the lost connection no compatible ECU connected. But no blinking ECU when I started the engine. I fired it up this morning and it kept the connection but was idling weird. At one point the engine stopped. It was idling weird so I went to up the idle to 900 rpms. I looked at the multiple live data screens and then wanted to see if there were any codes. Not sure if that’s what killed the engine when I hit that screen. There were no codes and like a dummy I pressed the clear codes. Not sure if that was what killed the engine. It fired up ok. And it kept the idle in tact when I put it into gear. Seemed to run very rich as the pipes were black. I hadn’t had that in the past. They were clean. I changed plugs and put in the fancy E3 plugs that are platinum and when I pulled out the old plugs last year changing them they were perfect in color. I adjusted the cranking fuel up this morning before firing it up since the last time I did I had to crank it a few times. Its funny the first time firing it up this year after it sat for 8 months, it fired up immediately. I think there’s a compatibility problem with the color screen handheld and the 1.0 system. Though FAST says its supposed to work. It constantly drops out and then connects. I’m afraid to keep it connected with the car running while driving as there seems to be no problems when driving it. I do get the pop sound when I let off the accelerator at fast speeds once I get it out on the road I’m hoping the new plugs which are supposed to burn more fuel than stock will help the popping. Some say its normal for H pipes. I have headers and flow master mufflers. Sorry for the novel. Just adding my experience since mine was put on around 8 years ago. Sometimes I regret not keeping it stock with the 2 bbl carburetor. No much horsepower since they cut it back in 1973 but easy to work with. And if I wanted to I used to be able to go to Advance Auto or the like and buy another one cheap.

  41. Jeff i have the 2.0 system in my 69 Chevelle big block. My fuel pressure at the regulator reads 50 psi and the hand held reads 62 psi. I have verified the regulator gauge is accurate with my fuel pressure tester. I have replaced twice the sensor on the fuel rail block. When i first changed the fuel block sensor it read 52 psi. The next day driving the car it was up to 62 again. I tried a GM sensor and and the same readings. The battery was bad and i replaced it. The powers and grounds are hooked to the battery.
    Do you think it could be the hand held unit?

  42. Christopher says:

    I have a 86 Monte Carlo Super Sport the system seems to do perfect until I reach 4000 RPMs start popping will not accelerate past there if I drive it and keep it under 4000 RPMs a works Perfect does anybody have any idea how come at 4000 RPMs it does this

  43. james hodgson says:

    Hey Jeff
    really appreciate the help you give everyone considering how useless the teck support line is at fast. i have the exact problem with over fueling. some background i have a GM 502 crate full MSD ignition system and 6 years ago i put the fast system on
    first couple years it worked pretty good until the fall and it would over fuel so bad a reboot was required. then the map sensor failed because it was full of fuel so did a relocate and moved it to the side of the unit with a vacuum hose.now the last three years its been slowly over fueling mostly after a long drive but it is getting sooner and sooner every time i drive it now it wont last a tank of gas. this is what i have done new wide band 02,new map again,moved vacuum to large 3/8 port on back of unit, smoke exhaust system,new plugs ( black as charcoal),checked for leaking injectors next step is to send them in for testing,called teck support 6 times in 4 years,all sensors read perfectly even used lab scope.filmed the master data list to look for clues and it seems it can add fuel but not remove it. only thing i found recently is my 6AL box was glitching out the car would buck every once a a while but this is new to this year so i bypassed the box and am running off distributor.still over fueling. im a teck by trade and i cant fix this thing thinking a Holley snipper kit is next.oh my ECU is mounted under my dash and it smells like burning electronics the support guy told me to send it in but from what i read they do a quick test and send back to you saying no problem found

    • Check the TPS switch and the IAC motor. As you can see, FAST systems are unreliable garbage and hard to diagnose. I switched to Holley Sniper XFLOW and junked the EZ EFI 2.0 and the FAST Sportsman XFI after repeatedly having to replace failed parts. So much for the FAST “lifetime warranty”. In between the failed FAST parts, I was able get the systems running well. Zero problems since going to XFLOW – and far better performance out of the box. You might also notice the FAST forum has been down for two weeks now. So, no help available from the trolls on that site. There were only a few people there that did help others, and most of them have left due to the trolls there. COMP Group product quality has been ridiculous across the board for years now. Vic Edelbrock recently bought the COMP Group which includes FAST. He just bought himself a severe headache.

  44. I have the first ezefi has work
    well for years now when I stab the throttle it almost stalled but after stumbling a few seconds takes off it use to just come to life also when driving at wide open throttle and start letting up
    You can feel it coming on harder

    • It sounds like your idle or cruise AF settings are off or your accel fuel setting may be too lean. A default or user set WOT AF setting could also be incorrect (often too lean). FAST EZ EFI also uses the AF idle and cruise settings to build cold idle and accel maps. The accel fuel setting is used in addition to these maps. If you have the early EZ EFI 1.0 and the old handheld, some of the finer tuning features are unavailable until the later EZ EFI 1.0 color handheld is installed with updated ECU software.

      FAST also updated the EZ EFI 2.0 handheld in 2019 to include two new features – but didn’t bother to tell any owners of older EZ EFI 2.0 systems. These are just more reasons to avoid FAST EFI all together.

  45. Just installed a Fast kit on my 78 C30 with a mild built 454. Runs decent on cold starts. But once you shut the truck off for five minutes it won’t start. You can hear the pump prime gets pressure fires and dies.

  46. Have a fast ecu the car runs real rich at start up.how do i correct that I’ve tried just about everything

  47. I bought an unfinished project that has a fast efi 1.0 in it. The truck has a 460 with a thumper cam and minor work to the heads. I have not been able to get it to run properly which I believe is due to the low vacuum (6-8). Is there a way to make the ez efi work on my truck?

  48. Stefan Hållberg says:

    How do I adjust the cold start to work properly.
    Engine is a 496 with FAST EZ-EFI gen 1 it starts immediately at 1300 rpm and immediately drops to 2-300 rpm and from there the rpm increase to the idle 850-900 rpm. This is the only problem I have.
    Idle Af is 13,7
    IAC is 15-20
    TPS is adjusted to the left(start) ofnthe target bar.
    Any ideas

    • Tony A. Welch says:

      I had the same for cold start. Did exactly what yours is doing. First I started a reprogram to get the bar in the center of green. Once the car is cold, start it, then go into your advance tuning, you’ll see where your cold start settings is, move up a point At a time to see if there is any changes, once your happy, select ok. It’s truly simple. What it does is give you more or less fuel for cold start. Good luck.

  49. Pingback: Ask Away! with Jeff Smith: Will My New EFI System Work With My Setup?

  50. Tony A. Welch says:

    I have the Fast EZ EFI System for my 1972 Pontiac grand prix 455. I’m absolutely happy. Amazing the improvement it makes. Follow the instructions, check everything because it matters! Now I’m a show off. And I’ve got haters now lol. I did have to do some tuning and now it runs awesome. 6 months no problem. I did switch to in tank fuel pump and new tank. World of a difference. Fast EZ EFI is no doubt the way to go guys. It made a believer out of my installers.

  51. Hi Jeff,
    I think I may have been misled by FAST tech support, but here goes. I installed a Fast XFI Sportsman system on a Ford 5.0 with engine mods including a Vortech 3.0 supercharger. It never has started after about a year of occasional tinkering trying to get it to run. After putting a noid light on the harness connections at the injectors, it stayed on all the time on 4 plugs and would not come on at all on the other 4. I found that the system was not firing the individual injectors on the intake, instead it was holding 4 injectors open all the time the key switch was on and not opening the other 4 at all. I found about 3 extra quarts of fuel in the crankcase. When I would pull the plugs, 4 on each bank would be wet and the other 4 dry. After talking to 4 different techs at FAST, they agreed to give me a RA number to send the ECU in for testing. Whenever I would run diagnostics on the ECU, it always showed no faults except for a CTS error. I sent off the ECU today, but now I am thinking there may be a problem in the engine harness. Have you ever heard of a bad harness in one of their systems?

  52. Sorry I meant 2 on each bank, not 4.

  53. I’m working with a 2.0 on a 454. It’s been great till now. It won’t start. Sent in hand held and ecu. Got a call from a tech saying ecu had a communication problem and was corrected and returned.Don’t hear the pulsing sound during cranking. Thought it wasn’t reading rpm but after connecting hand held directly to the ecu (won’t work with the extension cable) I’m getting 150 rpm during cranking. What’s my next step other than throwing it in the trash and going back to a carb as many have suggested?

  54. I have installed the system and it floods so can not get started. I have done all the wiring as described direct to battery and 12V switch source is god and tested, fuel pressure is right at 43PSI. When I crank the engine the Throttle body is closed but I can see lot of fuel getting sprayed and after I stop cranking I open the throttle body and look I can see flooded heaps of fuel in the manifold.

  55. Leo Toomey says:

    I have a Fast Ez efi multiport ,I got a bog on opening the throttle,just started playing with a 5.7 hemi on the stand,exhaust is a rigged up system using 2 open mufflers,had trouble getting idle to stop hunting and come into advanced idle target ,having fun think it’s throttle plate issue related

  56. I have a 383 stroker w/ fast fi… drove it home in the rain… next time tried to start it, no fuel pump power. tested the fuel pump, works fine…won’t work w/ the key

  57. Hi everyone, stumbled across you via Google. I have EZ 1 on a Ford 302. It suddenly cut out whilst driving, managed to limp home at 20mph by unplugging 3 of the injectors, it wouldn’t run otherwise. Handheld said 02 error so replaced but no different. Sometimes I get 02 Error and sometimes No Error. Still only runs with one injector but you can see the fuel guage dropping as you look at it. The ECU blue light is flashing rapidly. Even after leaving it for a week or so the garage still stinks of gas. Any help would be very appreciated.

    • Tim Halterman says:

      I had the same problem and they said to make sure I had a solid 12 volts to the pink wire. I checked and mine was getting interference from somewhere and was bouncing between 6v and 12 volts. And I was getting an 02 code and a rapidly flashing blue light. Made sure all my grounds were good and corrected my voltage problem. No issues with 02 or light since

  58. Josh landers says:

    I have a fast fuel injection on my 571 big block chevy 4150 set up in can get car fired up but won’t idle or stay running long enough to set timing or adjust anything

  59. Hi Jeff I have just installed an ezi efi and I have a reading of 53 on the map sensor. I have taken the sensor off of my other vehicle that reads26 to see if the sensor was bad both read the same engine runs but not very well. Any help would be appreciated

  60. david covell says:

    Hi Jeff,
    Like many others my fast 2.0 xfi is in a no start condition. No start tree from shop manual does not reveal any clues. Symptom has i) the first key on gives a no start, ii) second key on triggers the ses light in continuous flash mode (indicating ecu not found), III) subsequent key on tries will eventually yield a constant ses (good) and the engine will start. Considerable time spent looking for rouge grounds (as in your example with a grounded tach lead). Cam and crank sensors check fine. I realize this is not much to go on, but do you have any suggestions?
    Thanks, David

  61. Rob Harris says:

    Hi Jeff, I’ve been running a FAST 2.0 for several years now on my Pontiac. ’67 GTO stroked 400 (461) TKO 600 5 spd. Although I’m on my third ECM now (they were replaced at no cost) Overall I’ve been pleased with the performance of the system until recently. Like others I have discovered the difficulty in reaching assistance from them. I finally did get a reply through social media. My issue is this; O2 value incorrectly reads very high (usually max value) most of the time dumping excessive amounts of fuel in and running poorly and barely idling. No error codes. I’ve followed their advice checking for vacuum and exhaust leaks and found none. I replaced the O2 sensor. No change. When the sensor shows a normal reading (rarely) the engine will run great. Thoughts?

  62. hello, i own a ez fast efi, its on my 68 gto 428 4 speed ,its been parked for about 4 months never gave me a issue at all, so i go to start it and no go!!!!battery is charged up, fuel pressure comes on to 43 psi then bleeds off, go to crank it and nothing, turns over fine, just no fire up at this point. i than call fast tech line and no help, all my fuses and relays are fine ,i have 7 gallons of new fuel , when i installed the efi i followed all the directions to a “T” any idea what can fix this? i cracked the return line just to see if i was getting fuel through the lines and it squirted out as it had pressure, thanks for your help

  63. hello holley sniper
    my throttle blades not open enough to catch idle when pushing clutch in or going in neutral when coming to a stop ??
    blades are set @ 2-21/2 turns in when shipped 
    something has to be done it is unsafe to drive 
    i went to the mini mart  5 stops 5 stalls 
    thanks mj

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