Another fuel pump problem

[94VRCLUBBY]

Hi guys and gals.

Just looking for any help on my intermittent problem.

The fuel pump operates when the engine is cold. The car then runs fine until i switch off.

If the engine is warm i can't get it started again until i leave the motor to cool down again. While hot the pump does not prime, but i do get a 12V feed from the relay when cranking and on initial ignition on. So the relay appears to e ok.

Then the same thing happens.


I assume the pump is ok because i've never heard of a fuel pump intermittently faulty due to heat...??!!

So, next question is about the oil pressure switch which i read is linked in with the priming circuit.

How do i test it?
My Max Ellery manual is absolutely useless and will be going in the bin very soon.

Another question which may or may not be related is this


What is this? What does it do? And should i be getting 12V between the body and the part in the middle with ignition on. Also while ignition on i can hear a high pitch noise from it.

Thanks in advance, this problem is bugging the hell out of me.

 

[VR38]

The fuel pump operates when the engine is cold. The car then runs fine until i switch off.

If the engine is warm i can't get it started again until i leave the motor to cool down again. While hot the pump does not prime, but i do get a 12V feed from the relay when cranking and on initial ignition on. So the relay appears to e ok.

Then the same thing happens.


I assume the pump is ok because i've never heard of a fuel pump intermittently faulty due to heat...??!!

My pump did exactly this same intermittent fault after running the tank too low one day, new pump fixed it.

 

[94VRCLUBBY]

Ok, thinking out loud now,

If the engine runs, then while running i remove the FP relay, i assume the engine should still run as the fuel pump will be supplied 12V via the OP switch?

So if the engine dies, the OP switch is faulty?

 

[94VRCLUBBY]

My pump did exactly this same intermittent fault after running the tank too low one day, new pump fixed it.

Thanks, i've been reading that this could be a cause, so i''l try to get the pump to stop priming and bang the fuel tank. Apparently this may help if it is a seized pump. Hopefully it won't confuse me even more.

Still thinking engine should run without FP replay once started? So still possible OP switch problem? Although the oil light operates fine, i guess it could be the signal to ecu from the OP switch?

 

[94VRCLUBBY]

managed to get the car to the point the pump stopped priming again.

So i then managed to hook up my meter to the pump feed wires and the probes stayed in place while i switched on ignition, while being able to see the meter display.

Got power to the pump connector, so i guess it is the pump in the end. Strange symptoms though?

Anyway, when i replace the pump, hopefully the problem will be solved so i'l post up to confirm in case anyone ever has similar issues.

Nothing worse than finding a thread with no conclusion at the end!

 

[RUN415]

As you kinda say...can't see how a hot engine would drastically affect the fuel pump...besides the supply of power???
Although VR38 says a new pump fixed the problem...so who knows???

In any case, the oil pressure sensor feed is wired THRU the FP relay...so taking it out will stop the motor...but not really prove anything.
There's a good pic of the wiring diagram (towards the bottom - markovr's post #15) in this thread here...
http://forums.justcommodores.com.au/vr-vs-holden-commodore-1993-1997/142829-vs-commodore-fuel-pump-draining-0-74a.html

What power did you get when you tested the four pin plug that plugs into the fuel tank?
You should get dim power at pin 2 constantly (= fuel gauge) and strong power for 2 secs at pin 4 for the pump prime cycle.
May help to bridge out the FP relay base, so you get power to the pump regardless of ignish and everything else - this makes checking the power and wiring much easier. (On mine, it's slot 3 + 5 on the relay base)
Good luck.

 

[94VRCLUBBY]

On my pump there is a round 2 pin connector, which i assumed was power and earth for pump. Switched ignition on, got 12V ish for 2-3s then fp relay clicked off, then 0v. (had to dance from drivers door to rear of car to see meter behind rear wheel)

The smaller 4 pin i thought was just for the gauge so did no checks on that. When disconnected, gauge registered nothing.

Now this has happened before when i ran the fuel low about 6 months ago. Assumed it was **** in the fuel. After a while got it going again, then happened after another few K's when i stopped to fill up.

Got is started again. Only now has this problem come up again and seems to be more severe as i have to leave it a lot longer before the pump will prime again and happens every time i stop the engine after a drive.

 

[RUN415]

Ah...ok...I was describing my VS exec...obviously the setup on your VR Clubby is a bit different..soz.
It's just that I didn't find my intermittent problems (diff to yours tho) til I bridged the relay and found out the plug to the tank wasn't connecting properly. (a rare prob I guess)
Anyway, seems like you're getting power there...but these intermittent problems are difficult to diagnose eh?

 

[94VRCLUBBY]

OK, new pump fitted, test driven and all seems ok!

So the symptoms were strange but it was the pump at fault after all.

I now notice with the new pump that the priming noise is much steadier, whereas before with the old pump it sounded like it was speeding up as it primed.

I'd still like to know what the metal thing is on the shock strut though?

Thanks for pointers and assistance, posting up the thread just made me get my own thoughts together to narrow down the problem, but hopefully will help someone else in the future.