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help ! fuel pump issues

Discussion in 'Mechanical & Electrical' started by danh, Nov 2, 2008.

  1. danh

    danh

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    Me, balto and dad spent hours today trying to fix my electrical problems. fixed most of them regarding lights and motors .

    but we are still left with a big problem it wont start.
    there are sparks (dad found out the hard way)
    there is power at the relay in the drivers footwell,
    the relay works in another car, and the relay clicks on ignition in my car.

    but there is no power at the fuel pump.

    in the merit we tested it on 12v appears for a few seconds when the ignition is switched on, is this right ? or should there be permanent voltage at the fuel pump ?

    any ideas where to start to get it running again ?
     
  2. Lefthooker

    Lefthooker

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    when you turn the ignition, the fuel pump "primes" itself, pushing fuel forward, to make sure a clean start is made. This is the 12v flash you are getting (i presume) Im not entirely sure if 12v perm should be there ??
     
  3. danh

    danh

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    right, im not getting this 12v flash in mine up at the pump body wires however the 12v flashes at the relay and wiring connector in the drivers side footwell.

    I'm thinking that bridging the wiring between the relay output and the pump itself with a suitable length or wire will get the thing primed. What keeps the fuel flowing after it starts - surely the pump needs 12v to keep the supply constant - if it does where from?

    The wiring diagram on autodata suggests that the pump is earthed and the positive runs up to the fuse which then goes to the relay. Relay is clicking and energises from terminal A1 on the ECU so we are OK as far as that.

    I just cant see where there could be a sudden break in the wiring. All connectors checked(especially those under the car)

    :hang::hang::hang::hang:
     
    Last edited: Nov 2, 2008
  4. Lefthooker

    Lefthooker

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    Ahh ok, i misunderstood, thought you were getting the 12v at the pump.

    Ok, well at least this supports the case that either the wiring is bust, or the pump itself.

    As for the pump, i am consulting my wiring diagrams now :)
    Which engine do you have ? I presume the C14NZ

    As for why it only primes on start and runs constantly when the engine is running, this is becasue the ECU tells it to do this, otherwise you would flood the engine as soon as the key is turned

    Ok, take a look at this: (click here to download the pic for a better size) <- I put the pic on my homepage for downloading.

    German and english is shown.

    Red is the fuel pump itself, it has 2 wires, live coming from the relay and earth. If there is no power, either the live is broke, the earth is broke, or the pump itself is broken.

    Blue is the fuel pump relay, which as you can see goes right into the ECU

    [​IMG]
     
    Last edited: Nov 2, 2008
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  5. danh

    danh

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    Yup C14NZ Single point Injection.

    No codes stored in ECU.

    Replaced the fuel pump relay, all fuses checked / replaced. Been underneath and checked the connector adjacent to fuel tank sender unit. It seems the problem must be along that length of cable.

    Got me confused now.
     
  6. Lefthooker

    Lefthooker

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    ok, there are 3 possible faults here.

    1. live wire from relay to pump broke
    2. earth from pump broke
    3. pump broke

    To test if the pump is broke, get a long piece of wire, connect one end to the battery, and the other end to the pump + side. If the pump fires up, then the wire between the relay and pump is bust

    If the pump doesnt fire up then, lay another wire from the pump ground to batt ground, if it fires up then, you ned to fit a new earth

    if the pump doesnt fire up at all, then the pump is broken
     
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  7. danh

    danh

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    That is pretty much the conclusion I am coming to.

    Your diagram is just slightly different to my copy of autodata, but it shows the connectors whereas mine doesn't. I'm going to disconnect the pump and give it a seperate 12V supply - that is simple and should result in the pump priming and will rule out the pump being faulty.

    Then I'm thinking earth next followed by the 12v line.

    If that does't work, i'm going to find a very dark and very quiet room !!!
     
    Last edited: Nov 3, 2008
  8. Lefthooker

    Lefthooker

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    lol, elementary dear watson :)

    if it doesnt work, time to visit the local scrappy for a replacement pump :)

    Just dont forget, if the pump whizzes into life, dont let it pump too long or you'll flood the engine.
     
  9. danh

    danh

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    ta lefty :beer:, going to have a crack at this later on today.
     
  10. dark-ryder

    dark-ryder

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    hope you get it sorted mate, issues like this can be annoying i know, been through two pumps!
     
  11. danh

    danh

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    yeah so do i, im suffering withdrawal symptoms from not driving and this walking idea is stupid lol.
    im going to leave it alone and let dad do it, ive already made a big enough hash up as it is lol
     
  12. dark-ryder

    dark-ryder

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    lol i wish my dad would do mine! ive been doing the walking lark for over a week now and only got the car back for not even a day! does sound like a wiring issue tho, so as said above, test with 12v from battery :)
     
  13. Lefthooker

    Lefthooker

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    thats what us dads are here for lol
     
  14. danh

    danh

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    yep. and it becomes his problem if something goes bang lol. hoping to get this sorted tomorrow.
     
  15. danh

    danh

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    the car lives again, new wires from the pump to the relay and a new earth and it runs. well happy my car can be driven again and i no longer have to walk everywhere.
    lefthooker you have been a star once again so thank you. :beer:
     
  16. dark-ryder

    dark-ryder

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    glad to hear you got it working mate, wish mine was as simple!
     
  17. Lefthooker

    Lefthooker

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    always a pleasure :)
     

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