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Thread: E38 with t42 fuel pump woes

  1. #1
    Tuner in Training Scotimus09's Avatar
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    E38 with t42 fuel pump woes

    Been working on this for a little while and need a second pair of eyes look at it

    the problem is the fuel pump will not trigger via ecm controls

    Engine is a 6.0 ly6 with vvt delete (by way of camshaft)
    Computer setup is a E38 with a t42
    Harness is stand alone built by me (first gen4 harness but have built several gen 3 harnesses )

    Tune is set up for a fixed rate pump with no fpcm equipped selected
    have disabled starter checks and enabled vats1 and vats2 patches but still no pump
    the ecm is wired to have the constant battery voltage on the red wire and has a relay from ignition switching all pink wires on
    the fuel pump relay is wired to switch power with a voltage side of the relay switched from the ecm (according to gm service information and a few people on this forum 12volts comes from the ecm still seams odd but if thats how its done.)
    vcm controls will toggle primary pump status in the scanner to on and off but will not switch fuel pump on.
    fuel pump relay control is coming from pin 50 on x1 of the ecm and if power is connected the pump triggers on.
    if pump is jumped to power the truck will fire for a few seconds then shut off
    fuel cut type says none

    also work mentioning the throttle is not hooked up and am getting p2122 and p2127 and the tcm i am using is from a car and dosent match the 4l80e i have hooked on it will be taking care of these issues tonight, hopefully that is my fix

    im attaching my tune file if someone will look over it and see if i missed something it would be greatly appreciated
    Attached Files Attached Files
    Last edited by Scotimus09; 05-10-2017 at 06:37 AM.
    69 K20 ly6 4l80e np208 currently under the knife

  2. #2
    Advanced Tuner veee8's Avatar
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    Did you do "Write Entire" or "Write Calibration" when you disabled the VATS etc?
    www.crawford-racing.com
    Home of the original and best selling CR-Fueler plug and play port injection controller kits for all GM Gen V direct injection platforms.

  3. #3
    Tuner in Training Scotimus09's Avatar
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    i did a write entire
    69 K20 ly6 4l80e np208 currently under the knife

  4. #4
    Advanced Tuner
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    Have you metered the output of the ecm, to make sure it is does output 12v, or metered it just in case it is a lowside output? Or try different pw in the fuel pump control. When I had a standalone pump output trigger a relay, it worked better lowering the pw. Or you'll be buzzing your relay. Not quite sure if that is what you're trying to do. Sorry if I misunderstood what you're tryin to do.
    Last edited by h2.4; 05-11-2017 at 01:17 AM.

  5. #5
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    on X1 pin 50 is the green with white tracer that is 12+ output put to the FRCM/your fuel pump relay. I just did a FPCM delete and connected this wire to my relay directly and works as advertised. in the tune need to turn P069e and p0230 off. Also pin 47 is a pink with black tracer that is ignition voltage. just food for thought.

  6. #6
    Tuner in Training Scotimus09's Avatar
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    i have put a meter on the output of pin 50 its only outputting around 2.5 volts, i have ohmed the wire in pin 50 from end to end and there was only 3 tenths of a ohm and the terminal tension is good. i have ignition voltage put into pin 47 but will definitely verify there is voltage on the pin. both codes po69e and p0230 are set to no error reported.
    ke5gnz will you post your tune so that i can compare ? thank you everyone who has put input in i appreciate the help
    69 K20 ly6 4l80e np208 currently under the knife

  7. #7
    Tuner in Training Scotimus09's Avatar
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    borrowed another ecm from a friend and fuel pump comes on no issue. looks like my ecm may be bad
    69 K20 ly6 4l80e np208 currently under the knife

  8. #8
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    glad you found it just got back I can post tune this evening if still neede

  9. #9
    Tuner in Training Scotimus09's Avatar
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    went to the junk yard and got a new ecm did a write entire on the ecm and now its fixed
    69 K20 ly6 4l80e np208 currently under the knife