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Thread: hard starting/long crank time

  1. #1
    Fuel Injected! kunsan1987's Avatar
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    hard starting/long crank time

    Well i went and did it.My conversion is done except for the O2 sensor,park switch,400 kickdown and of course to hide the rats nest.
    my truck is a 1983 C20 converted to 4WD.350 ci,th400,np208.
    I'm using a 7747 with ACSW (this came out of a 88 K30 5.7l,th400,np208).
    I hope some one can help me with a couple of questions.
    1. the truck does not start until oil pressure is up to 30 psi(guage reading).The ecm is signaling the fuel pump for apx. 2 seconds(checked at the pump).the electrical system looks good relay,etc.could this be a fuel regulator/pressure problem?


    2. will it adversely effect anything if i dont hook the trans kickdown to the ecm right away and stay with the pedal mounted switch?

    Thanks,Jim

  2. #2
    EFI GearHead ! EagleMark's Avatar
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    We are having the same issue here:
    http://www.gearhead-efi.com/Fuel-Inj...erPro-software

    Since you have at least a prime time of 2 seconds, it sounds like a different wiring issue. The relay has to be on at key on for 2 seconds then on when cranked too.

    A1 Green wire white stripe turns on relay, then it needs a fuel pump signal to B2 usually Grey or Tan.
    http://www.gearhead-efi.com/Fuel-Inj...8&d=1331599730

    Do you have the crank wire hooked to starter solenoid that senses when in crank position? C9 Purple or Purple White.
    http://www.gearhead-efi.com/Fuel-Inj...0&d=1331599730

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  3. #3
    Fuel Injected! kunsan1987's Avatar
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    I'm getting a signal on the GRN/WHT wire.I'll have to check B2 tomorrow and C9 crank signal is hooked up and working.
    thanks

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    It's also possible that there's a calibration issue if you're still using the older engine. Does it happen with every start regardless of the engine temp, or is it after sitting for a while? Are the injectors delivering fuel immediately on cranking or is there a delay? How many seconds of cranking does it take before the engine fires up?

  5. #5
    EFI GearHead ! EagleMark's Avatar
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    Do tell on what your thinking the calibration issue is! I've never had an issue like this, but then I always start with my own chips.

    ACSW was superceeded twice to AMUS...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  6. #6
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    ECM delivers a bunch of fuel up front then reduces it the longer the engine is cranked. If mix is too rich it may take a while for it to lean out enough to fire. Early '80s engine had different heads and cam and wasn't always as friendly to EFI swap. Add adapter to top of 4bbl manifold and things really change. More advance can help but cranking fuel table adjustment really makes it better. Sometimes you can diag too much fuel by cranking for 1-3 seconds, stop crank, open throttle to floor (clear flood mode) and crank again. If it fires right up then suspect too much fuel. But none of this matters if there's an issue with getting fuel to the injectors in the first place.

  7. #7
    Fuel Injected! kunsan1987's Avatar
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    I checked B2 and i'm getting a 12v signal for about 1-2 seconds.

    It happens every time cold or warm cranks for 3-4 seconds then fires and idles fine.when i rev up the engine i was getting backfireing through the TB.slow increase of throttle is fine.Distributor is set to 0*.Edelbrock performer intake,1/4 inch steel adapter plate.

    I changed the ecm to one from turbo city.i dont know what was changed or what bin it is but the truck runs a whole bunch better no backfires and good throttle response.Although it still has the long crank issue.I'm using an Airtex E8153(not the best choice) I'll upgrade to a E8094 fuel pump when i can.
    Attachment 2362
    I'm going to order a GQ-3X and some chips from mcumall this week.then i'll get the data i need
    http://www.mcumall.com/comersus/stor...idProduct=4225


    thanks guys

  8. #8
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    Well, that looks like the ecm had a calibration for a Vortec headed 350 with 68# / hr injectors. It's probably leaner overall than the stock one since the injectors were larger. Do you know if you've got stock injectors in the TB? Did that ecm go with the TB that you used?

  9. #9
    Fuel Injected! kunsan1987's Avatar
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    as far as i know the injectors are stock everything came out of a Caltrans truck.The ecm was ACSW and did not run very well.
    I took a drive around the block and i have fuel issues i think,truck died on me looks like the fuel pump lost prime/got a air pocket.With the TC ecm the truck ran pretty good(until it died).i going to find my pressure gauge and check that next and maybe a regulator rebuild

  10. #10
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    I've had maybe one regulator fail on a TBI in 20 years as a tech. It might be bad but that's not the first component I'd suspect. Check basic stuff. If your tank is for a carbureted truck you might have issues with fuel sloshing away from the pickup tube. Might have issues with a fuel filter plugging (filter on suction side of pump can cause problems for pump). Put a fuel pressure gauge on it and go driving. The programming in that TC ecm is probably way off compared to the stock one so I'd try and stick with the OE ecm for now.

  11. #11
    Fuel Injected! PJG1173's Avatar
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    don't forget to look for restrictions in the return line. I had a similar problem getting too much fuel while cranking.
    87 4Runner, 15" spring lift, 3" body, chevy vortec 355, 5.29 gears, 38.5x15.5x15" Boggers, 280hr, 16168625 running $0D
    93 S10, 12" spring lift, 4.56 gears, F/R lockers, 36x12.5x15 TSL's, long tube headers, 266HR cam, p&p vortec heads, $0D Marine MPFI.
    05 Silverado, 2' lift, 4" exhaust, Bully Dog programmer,

  12. #12
    Fuel Injected! kunsan1987's Avatar
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    I checked my fuel pressure and the max reading i ever got was 9 psi.i do believe thats a tad low.it's a brand new E8153 rated for 9-14 psi.it works fine in my 4.3l rock crawler,but either its a crap pump or 5.7l needs more.there are no restrictions in the return line.Maybe it's a combination of low pressure and off calibration.

  13. #13
    EFI GearHead ! EagleMark's Avatar
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    Or a fuel pressure gauge that is wrong again...

    Now if it's correct then 9 PSI sucks and yes these motors will run but not worth a squat. But do you still have 9 PSI when cranking over?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  14. #14
    Fuel Injected! kunsan1987's Avatar
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    the highest reading i saw was 10psi for a minute 9 seems to be the norm.

    i bought an ftdi breakout board at frys.it works great with winaldl,but tunerpro rt connects to it until i plug in my aldl.i've followed all the tips i saw in the orther thread still no joy.
    so here are my logs from winaldl.If im reading these right i am lean all across the board.so my fuel pressure needs to be addressed first i think.
    Attached Files Attached Files

  15. #15
    EFI GearHead ! EagleMark's Avatar
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    OK 9 psi... let me guess... the BLM are lean right?

    I looked at the BLM and they are lean... I can forsee the future!

    9 PSI sucks
    The best trick in the book of TBI is to have 13 PSI on a stock bin and stock motor.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

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