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Thread: fuel pump constantly runs

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    Default fuel pump constantly runs

    hi all
    just picked up a 99 ZX2
    when the battery is hooked up the fuel pump runs..constantly.
    after driving it home, the pump stopped when i shut off the car, but when i went out later it was running again. i think *maybe* the fuel pressure sensor is bad (on the fuel rail?) and it is telling the pump to run...not sure how it is doing that though when the key is off...

    any other ideas? the PO replaced the fuel pump. maybe a crossed wire? bad installation?

    fuel pump relay? or this other module i have read about with all sorts of relays in it?

    thanks

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    Default

    having just got the car means you are going to have to examine it to make sure the previous owner was not one of those people who thought it would be a good idea to wire it differently

    also, provide an actual image of your engine compartment as this information will help me to better help you
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    Will do. I can access the pump from under the back seat correct?


    Quote Originally Posted by dareall View Post
    having just got the car means you are going to have to examine it to make sure the previous owner was not one of those people who thought it would be a good idea to wire it differently

    also, provide an actual image of your engine compartment as this information will help me to better help you

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    Yes that is correct


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    Could it be a bad relay? If the switched legs were in constant contact I think that would make the pump run like that or whatever messed up wiring could somehow do it like dareall said
    It's a POS but it's my POS

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    Ok, I also found the electric radiator fan was unplugged. When I plug it in and hook up the battery. It and the fuel pump start running. I think it's the relay box under the air filter....what do you all think? Hopefully I can grab 1 or 2 at the junkyard. Other threads sound like this box of relays goes bad somewhat regularly...

    Thoughts?

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    Sounds like a good plan. If it's not the relays themselves it could be the wires underneath shorting

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    Wait that's the box with the big connector going into it?

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    Replaced the module...same results. Started cleaning grounds and now it has the issue intermittently. Must be a bad connection somewhere....might be in the ignition because when I fiddle,with it...I can make it all,shut off...
    Last edited by bluebronco69; 04-29-2017 at 06:26 PM.

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    I will probably pull the back seat next and look at the wiring and grounds down there, also the fuel pump module in the trunk and it's grounds... Post 10 here:
    http://teamzx2.com/threads/27103-Fuel-pump-problem

    Also I will probably combine all the grounds that go to the quick connects on the battery. Switch to a ring terminal that bolts to the battery clamp or something

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    Ok so here is what I have so far....
    Not the relay module under the airbox.
    I disconnected the ignition switch and when I hook the battery back up the radiator fan and fuel pump run.
    I unplugged the fuel pump and the fan still runs, so not bad wiring there.
    Unplugged the fuel pump module,in the trunk. Fan still runs.

    When I pull either fuel injection fuse (Underhood, or underdash) the fan and pump stop, so there is a crossed wire in,that system?

    What else could I try?

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    im thinking about the PCM now...based on some other threads i was reading...

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    A voltmeter is a cheaper.
    Quote Originally Posted by david gettle View Post
    I had a claim last year because I hit a frozen pile of manure
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    Nope.
    Took the pcm and found some burnt capacitors. Replaced the pcm. Didn't solve the issue.
    Found that when I unplugged the oxygen sensor the fuel pump and fan stop. Tried replacing the oxygen sensor and no,change. I also get code p0135 but not sure why...
    Read something about a oxygen sensor ground to the power steering pump...haven't investigated that yet though.

    The issue now reliably goes away if I shut off the car, then turn the key back to on. Then turn the key off.
    So still searching

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    Ccrm

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