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Bypass fuel pump relay (Nissan Altima)

Discussion in 'Electronic Repair' started by Martik, Jun 2, 2006.

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  1. Martik

    Martik Guest

    My relay failed and I want to bypass it to ensure the pump is working. Will
    this cause any problems? Why is there BOTH a fuse and relay in this circuit?

  2. carneyke

    carneyke Guest

    You must not be very experienced. The fuse is there for an obvious
    reason. Find the contacts for the relay and place a wire in the socket.
    When you know it's the relay (cause the car starts), remove the jumper
    and get a new relay. The relay is activated by something (it turns the
    pump on as needed) and never stays "on" all the time. Why don't you
    test the relay or spend $20 and get a relay ?
  3. Guest

    I suppose you know about this car. My one car's fuel pump is always ON.
    First there is a sort of smoothing regulator then it feeds into another
    bypass regulator. Over the years I have become intimately familiar with
    my Nissan Datsun 280Z

  4. Jim Yanik

    Jim Yanik Guest

    If the relay is the same as the "main relay" used in Honda products,it
    probably has a bad solder joint,and can be taken apart and resoldered.
    I've done it and had no problems since.

  5. bloggybob

    bloggybob Guest

    the relay is used as a switch to carry battery current to the pump from the
    battery which is controlled by the ignition switch through the relay trigger
    wire ... you dont have to use a factory relay ... just get a standard SPST
    relay at 30 amps will do fine .... and use a 20 amp fuse on the B+ constant
    12 volt lead ....

    as far as wanting to bypass to test it ? find the two biggest wires going to
    the relay and connect them together .....

    regards ....
  6. Jamie

    Jamie Guest

    yes it will cause a problem.
    the pump is very capable of generating
    more pressure than is needed and should blow the fuse.
    you have fuel regulators that operate the
    relay, fuses are in line in the event that
    for lets say the regulator does not shut off it
    then should cause the pump to bind up enough to
    blow the fuse.
    never put in a fuse larger than what belongs in
    the fuel pump line.
    the question is, is it your relay that failed?
    was it burnt contacts,open coil or maybe the
    fuel regulator failed which is also a set of contacts
    which can cause erratic operation of your engine
    when you need the HP!.
    you can for a moment jump the relay just to
    listen for the pump on action but do not leave it
    that way.
  7. Martik

    Martik Guest

    The relay was ok, I was not testing the right terminals.

    Turns out the problem is oil leaking into the distributor and contaminating
    the optics
  8. Art

    Art Guest

    Yupper: Comtaminated optics in the distributor will kill the fuel pump
    always. Datsun found that out long ago, then changed their name. LOL BTW
    Cheers on actually finding the actual problem.
  9. James Sweet

    James Sweet Guest

    Turning on the pump won't cause any problem, there's a pressure
    regulator on the fuel rail that will bypass any excess fuel back to the
    tank, and the pump itself will also contain a pressure release valve.
  10. Martik

    Martik Guest

    It wasn't easy, but with a little reading in some Nissan forums problem
    solved. What a dumb design, rubber seals that wear out and allow oil to
    contaminate. Hopefully some RV sealant will permanently stop future leaks.
    It's a $900 distributor!!!
  11. Jamie

    Jamie Guest

    ha, valve cover problems?
  12. GregS

    GregS Guest

    Good reason not to use optics. Use Permatex No-Leak rtv gasket maker.

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