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  1. #1
    Junior Member jderekt's Avatar
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    Default Fuel Pump Control

    I am very new to the tuning world and this forum, so please bear with me. Mods please move if in the wrong category.
    I am working with a 98 S10 ZR2 truck, it has a custom built 4.3 with an 0411 pcm upgrade running 02 blazer OS. My question is the fuel pump runs for no less than 30 sec after shutdown. I know the pump will run a few seconds after shutdown, but this seems excessive. Is this normal?? Where in the tune can I find this setting? I have searched but have not found it. What am I missing?

    Thanks in advance for any help you all can provide.

    Derek

    4.3L Vortec
    0411 PCM
    .020 over bore
    Comp 266HR cam
    Comp roller tip rockers
    Volant cold Air Intake
    Mercury Marine intake manifold
    JBA stainless shorty headers
    Borla full exhaust with high flow cat

  2. #2
    Joe (Moderator) joecar's Avatar
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    How is your PCM and FP wired...?

  3. #3
    Junior Member jderekt's Avatar
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    PCM is Controlling the factory fuel pump relay in fuse block, So using stock 1998 controls.

  4. #4
    Joe (Moderator) joecar's Avatar
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    Are PCM switched power inputs wired to switched power (and not hot at all times)...?

    ~ by phone ~

  5. #5
    Junior Member jderekt's Avatar
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    Well as far as I know they are. I'll have to check that.

    Sent from my SM-G935P using Tapatalk
    1998 S10 ZR2 Ext Cab.
    4.3L Vortec
    4L60E Auto trans
    0411 PCM and Engine/trans harness
    .020 over bore
    Comp 266HR cam
    Comp roller tip rockers
    Volant cold Air Intake
    Mercury Marine intake manifold
    JBA stainless shorty headers
    Borla full exhaust with high flow cat

  6. #6
    Junior Member jderekt's Avatar
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    Was finally was able to get back to this. Switched power pin-out is confirmed, although I did discover going by the pin-out I was originally provided, I do not have battery+ on C1 pin 57. The pin-out I have lists it as unused?
    I do have it at C1 pin 20.
    Switched power is at
    C1 pin 19 ckt-439
    C1 pin 75 ckt-1020 (OFF/ RUN/ CRANK voltage)

    Sent from my SM-G950U using Tapatalk
    1998 S10 ZR2 Ext Cab.
    4.3L Vortec
    4L60E Auto trans
    0411 PCM and Engine/trans harness
    .020 over bore
    Comp 266HR cam
    Comp roller tip rockers
    Volant cold Air Intake
    Mercury Marine intake manifold
    JBA stainless shorty headers
    Borla full exhaust with high flow cat

  7. #7
    Junior Member jderekt's Avatar
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    Has taken me a long time to get back to this (truck has been sitting a lot) but I've finally figured out this issue. Turns out the oil pressure sensor, which in 98 was still part of the pump circuit, is slow to bleed off pressure. Which keeps the pump running until the pressure drops to 10psi or so. Which means I've apparently got debris in the sensor.....sensor was replaced when motor was rebuilt. So new sensor going in after I purge that oil passage a bit.
    And this circuit is going to be removed to eliminate this completely.

    Sent from my SM-G950U using Tapatalk
    1998 S10 ZR2 Ext Cab.
    4.3L Vortec
    4L60E Auto trans
    0411 PCM and Engine/trans harness
    .020 over bore
    Comp 266HR cam
    Comp roller tip rockers
    Volant cold Air Intake
    Mercury Marine intake manifold
    JBA stainless shorty headers
    Borla full exhaust with high flow cat

  8. #8
    Lifetime Member
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    Quote Originally Posted by jderekt View Post
    Has taken me a long time to get back to this (truck has been sitting a lot) but I've finally figured out this issue. Turns out the oil pressure sensor, which in 98 was still part of the pump circuit, is slow to bleed off pressure. Which keeps the pump running until the pressure drops to 10psi or so. Which means I've apparently got debris in the sensor.....sensor was replaced when motor was rebuilt. So new sensor going in after I purge that oil passage a bit.
    And this circuit is going to be removed to eliminate this completely.

    Sent from my SM-G950U using Tapatalk
    And here I always thought I had a sticky fuel pressure relay. I'll have to pay attention to if mine lingers longer cold than warm to confirm. I can also watch the oil pressure gauge too I imagine.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  9. #9
    Joe (Moderator) joecar's Avatar
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    Which year/model/vehicle do you have...?

    ( I didn't think that the EOPS was involved in the fuel system )

    Do you have a wiring diagram...?

  10. #10
    Junior Member jderekt's Avatar
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    Quote Originally Posted by joecar View Post
    Which year/model/vehicle do you have...?

    ( I didn't think that the EOPS was involved in the fuel system )

    Do you have a wiring diagram...?
    98 S10 ZR2 truck, and yes I have factory manuals on computer and print versions. It does show it, and I have verified the wiring is as shown in schematics.

    HMP Tiff Hotspot Viewer_98fuelpump.pdf

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