issues with fuel pump not working I need advice

[Bruce Rhind]

1992 GQ 4.2 EFI

The only wire that has been cut and then rejoined via the fuel pump cut out relay is the White / Purple trace wire. I do not have any power in the original connector for this wire.

Does the engine have to be winding over for oil pressure or some other means to supply power to this White / Purple trace wire to receive power? Just with ignition on there is no power to this wire and I think this should be the power wire to the pump.

The White / Purple trace wire connection is isolated by the remote relay.
I am confused about this wire that it connected to both the 85# and 86# as there is a jumper wire between them.
The 86# runs up to the dash and could be an earth in the fuel cut out circuit and 85# is also joined to the White / Purple trace wire. If this is the fuel pump power then would this create a short from power to earth?

In the workshop manual on a two wire pump Power and Earth the supply for the pump is from fuse to the relay via the air regulator.
(To me it would be more logical to go through the oil pump switch, no oil pressure no power to fuel pump). For starting it could be supplied via the starter solenoid.

Fuel pump / Sender has five wires.
Clockwise starting at the 7 o’clock position (Black) and looking down onto the unit
Yellow / Blue trace ?
Blue / Red trace not a clue?
Yellow ?
White / purple trace ?
Black Earth


Original Wiring plug

Locking clip middle right side
Clockwise from this clip
Yellow / Blue trace could be fuel sender gauge
Blue / Red trace not a clue
White / Purple trace Might be power to fuel pump No Power
Black Earth
Yellow Could be fuel sender Power

To me I think the wiring is:

It appears that the Yellow / Blue trace and Yellow could be for the fuel sender / gauge


Remote fuel pump cut out Relay:
30# goes to White / Purple trace
87# green wire not connected
87a# goes to White / Purple trace
85# goes to White / Purple trace
86# jumper to 85# then a wire runs to dash


Could I run a power wire from the + battery terminal to the White / Purple trace wire on fuel pump to see if the fuel pump is working? If I do this should I remove the relay from the fuel pump cut off circuit?

Hope this is not too confusing.

Bruce

[Parksy]

Instead of getting a signal from the pressure sensor like you suggested, it gets its signal from ignition. When you switch the key to on, the fuel pump will run for about 5 seconds, then switch off. It will only turn on again when ignition has begun, ie engine started.

[NissanGQ4.2]

I have no idea as per usual, but I do know a bloke that has a fuel pump that is not being used if you would like to borrow it

[4bye4]

I am confused about this wire that it connected to both the 85# and 86# as there is a jumper wire between them.
55493
As you can see, 85 and 86 are usually the opposite ends of the operating coil. Having the same wire on both and a jumper between them doesn't make sense. Mabey its not a standard auto relay.

[NissanGQ4.2]

I am confused about this wire that it connected to both the 85# and 86# as there is a jumper wire between them.
55493
As you can see, 85 and 86 are usually the opposite ends of the operating coil. Having the same wire on both and a jumper between them doesn't make sense. Mabey its not a standard auto relay.

Is that for a GQ or GU????

[4bye4]

Thats just a generic auto relay. Normally the wire connections are the same for any make or model. Thats why I put it up cos its unusual to connect 85 and 86 together unless the relay is different to all other cars.
Why would you have a special realy but keep the same pin numbers? the idea is that if you go Holden Ford Nissan or mercedes or what ever, 85 and 86 is usually the coil. 30 is usuall power into the unit and 87 87a is the load side.

[Yendor]

Hi Bruce,

On EFI vehicles the fuel pump is controlled via the Engine computer (ECU) The ECU switches the fuel pump relay on and off. When the ignition is turned on the fuel pump should run for a few seconds and then stop. It should then start up again once you turn the key to start the engine.

Is the remote relay wired in before the fuel pump relay or after?

The Yellow / black is for the fuel gauge. The Yellow / blue is for the low fuel warning light.

The Blue / red and White / purple I'm not sure....but because you state there's a White /purple at the cut out relay I'm guessing that's the one for the fuel pump.

Yes try putting power in the White /purple wire. I would leave the cut out relay in for now.

[Bruce Rhind]

Hi all,
Thank you for your suggestions. Went out tonight and had my wife turn the motor over to check the wiring with the engine cranking. Yes you gusset is it started straight away.
Maybe the pump is on the way out. When it did not start it was firing but would not idle or run as there was not enough fuel pressure. Usually I turn the key on until I hear the fuel pump stop and then just flick the starter and it starts straight away.
Will put a new fuel pump on the vehicle tomorrow and hope for the best.
Thank you all again, Bruce

[Yendor]

Have you removed the fuel pump from the tank yet? It might just have some crap over the pick up sock or the wires have started to burn/melt where they pass through the metal plate.

[NissanGQ4.2]

Have you removed the fuel pump from the tank yet? It might just have some crap over the pick up sock or the wires have started to burn/melt where they pass through the metal plate.

Thanks Rodney for your help

No the pumps still in, When I spoke with him earlier he was going to by a new pump tomorrow anyway and see if the issue comes back or not

Cheer mate

[NissanGQ4.2]

Spoke 2 my old man today, its an electrical issue.

He bought a new pump anyway and still has the same problem.....works then doesn't work