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  1. #21

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    I will check that out. Thanks!
    Jess

    1991 Suburban


  2. #22

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    Post what fixes it and i'll do the same if i can get mine fixed...maybe we both have the same gremlin.

  3. #23

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    I will definitely post it...Once I can figure the damned thing out! LOL

  4. #24

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    I don't remember what pin it is right off, but one of the pins in your diagnostics harness is the power feed for the fuel pump. so if you don't hear your pump running when it won't start, you can put a test light to that pin and see if your pump is bad or if you aren't getting power to it. If no power, could be either the relay, a bad ground, or the oil pressure sensor. The wire in the harness to check should be the Grey wire.
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

  5. #25

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    The oil pressure sensor for it starting intermittently? How so? I've replaced the relay, fuel pump and fuel filter already. What ground do you think could cause this?

  6. #26
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    Surburbeast, The fuel pump is wired through the oil pressure switch so if your engine loses oil pressure it will kill the fuel supply & the engine will die. This is just a safety function in case of a wreck so you don't continue pumping fuel & start a fire, or feed one that's already started. It also saves engines if your oil pressure dropped & you didn't happen to be watching the guage. On older models this is handled by a 2nd switch down on the lower left near the oil filter. On newer models this is incorporated into the same o p switch that runs the guage, thus the 3 wires on it.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  7. #27

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    So that may cause intermittent starting and rough idle? How can i check this?

  8. #28
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    No guarantee that this is your problem but it's something to check since you've done most everything else related to the fuel pump.
    The best way is to just pull the wires off the switch & hook them together tightly & wrap them with some electrical tape & test it for a few days. Note if the wires are loose when you pull them off. If they're loose on the switch, then this may be it. If they're tight on the switch, & bridging them fixes your problem, then the problem is the switch, rather than loose wire connections. I believe the 2 wires you're wanting are orange & gray but don't quote me on this. Look on your switch & see what colors your wires are. If they are gray, orange & the 3rd is blue ( I think), then orange & gray are for the fuel pump, but again you should look at a wiring diagram for your vehicle cuz GM has been known to change color codes just to keep us from working on our own vehicles

    **edited, wrong color, changed green to blue after I posted
    Last edited by stephan; 02-16-2011 at 03:57 PM.

  9. #29

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    ok thanks for the help I'll check it out asap

  10. #30

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    I know the output to the fuel pump is the grey wire. I believe Stephan is correct with the orange being the power feed.

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