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Fuel pump /auto choke relay

Discussion in 'Sensors and Actuators' started by Nissanpowerhouse, Jun 25, 2019.

  1. Nissanpowerhouse

    Nissanpowerhouse

    4
    0
    Jun 25, 2019
    Hi guys I have a 94 Nissan bluebird/altima ka24de I'm having trouble starting my car after bridging the fuel pump relay to drain my fuel tank.
    I have noticed the fuel pump will only run when the relay us bridged but when I put the relay back in the fuel pump doesn't work so the car won't start any ideas what the problem is?
     
  2. Tha fios agaibh

    Tha fios agaibh

    1,987
    646
    Aug 11, 2014
    Why did you have to drain it anyway?

    Is the relay getting control signal from the ECU module?
    A scan tool would be helpful to manually turn on/off to see if it's cycling and/or diagnose if there's a fault code inhibiting it from comming on.
     
  3. Alec_t

    Alec_t

    2,702
    715
    Jul 7, 2015
    Hopefully you didn't bridge the relay coil terminals. That would likely have fried whatever drives the coil.
     
  4. 73's de Edd

    73's de Edd

    2,744
    1,133
    Aug 21, 2015
    Sir Nissanpowerhouse . . . . . . ( possibly . . . . now being Nissanpowerlesshouse )

    WELCOME . . . . . . to Electronics Point and sometimes Gas Monkey Garage . . . .

    I have noticed the fuel pump will only run when the relay us bridged.

    And is it actually still pumping fuel now ? ( The car will run )


    USING REFERENCING BELOW . . . . .

    FIO . . . . Relay # I I normally is in the right contact position leaving no power connection to the fuel pump.
    Then with an ignition switch turn on, the other contact position (as is shown) routes power to the fuel pump via BL to R/BL.

    YOUR mentioned relay is being read as RELAY # I in the wiring referencing, when bridging, you are simulating it having its BL/W to B contacts closed ..
    Then IF all is well in the ECM it will permit lower B wire on the FUEL pump , get connected to BL/W wire of the relay.
    THEN IF relay # I has 12 V across its O to BL coil the relay contacts should close from BL/W to B and let the pump have power.

    Now, do you have 12 V across the O-BL coil of relay # I ?



    Tell us how LONG OF A TIME that you needed to run that pump to do your task.
    Looks like a case of using a temporary duty item for a continuous duty application and possibly overheating, all the way to its demise.
    Typically, you step in the car and turn on the switch and the pump does a quick thumpa-thumpa to ramp up to pressure and the associated pressure switch internal of the fuel pump, then turns off the unit.
    Then as your fuel demand depletes the static fuel pressure, that causes the pressure to drop down to that pressure threshold where the switch closes and takes a THUMP or two to come up to full pressure again.

    Now you had that unit continually running into a non pressurized condition and progressively heating up. . . . . to be or not to be damaged ? ? ?



    Wiring Info . . . . .
    upload_2019-6-25_8-9-53.png



    73's de Edd . . . . .



    Saved me some good money, big time, this year, by buying our Halloween candy at Aldi's.
    I just hope the kids like Skattles and 4 Musketeers.

     
    Last edited: Jun 25, 2019
    Tha fios agaibh likes this.
  5. Nissanpowerhouse

    Nissanpowerhouse

    4
    0
    Jun 25, 2019
    I had to drain the tank to change the fuel filler hose I practically had a full tank of fuel so it took a while but I turned it off after filling up each 20 ltr jerry can x3.

    I'm not sure if the relay is getting a control signal. I just know that bridging the relay between the relay plug is the only way to get the fuel pump to work.
    I will get a scan tool hooked up and run the diagnostic test done.
     
  6. Nissanpowerhouse

    Nissanpowerhouse

    4
    0
    Jun 25, 2019
    I think that's what I mite have done is there a way to fix this?
     
  7. Nissanpowerhouse

    Nissanpowerhouse

    4
    0
    Jun 25, 2019
    Yeah thanks for the diagram I see know what I did wrong I followed the the diagram on the top of the relay which I put BL/w to O and B to BL. I then rectified that when I realised there where numbers on the inside of the relay plug so now it's B to BL/w and
    B to O. Is there a easy way to fix this problem like changing the ECU or the #2 safety relay as it's getting tiring to warm the car up like a carburettor with out it's auto choke working properly?
    Also to answer your first question yes the fuel pump is working.
     
  8. Tha fios agaibh

    Tha fios agaibh

    1,987
    646
    Aug 11, 2014
    B to BL is a direct short so you probably have a blown fuse. I don't think BL/W to O would cause a problem but never guess at electrical stuff. You could have fried a control module that could cost you hundreds of dollars.
    Thankfully many ECUs have current monitoring to protect from overloading.
    (I know American cars do anyway.)

    Sometimes you can reset the fault by disconnecting a battery cable for about 30 seconds.

    Thanks 73's de Edd for the great illustration and cornball jokes. (It always brings me a smile)
     
  9. Alec_t

    Alec_t

    2,702
    715
    Jul 7, 2015
    If you fried the coil driver (the ECCS control module) I doubt it's fixable :( .
     
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