Not pumping fuel

[leslloyd]

I seem to have a problem getting my VL to run,all i get is a try but it won't keep running.
I've removed the filter just upline from the pump at the front of the tank.And connected a
clear hose into a can,just to test the pump.So when i turn the key on i get fuel pumping
for about 3 seconds,the same noise as always on first startup,
I was expecting it to just pump the tank dry.Or am i missing something.
Is the pump buggered?Hopefully the internal pump is ok.
colin

[centy]

well on vn and vp the pump only op erates for a couple seconds when key turned intill the engine starts or oil pressure rises.
try same trick but bypass the relay with a piece of wire.

[leslloyd]

How can i?I've said i've taken the filter off and have the fuel hose shoved into a can.So why doesn't fuel pump into the can?
colin

[crazybiker]

Does the car start and stay running? If yes, it works. Leave it.

I don't know about the VL's, but the VN's cut-off the pump after a few seconds anyway.

[leslloyd]

I've just gone out and switched the key on and theirs an immediate flow thru the clear plastic hose,for about 3 seconds and say 2 cupfuls of fuel.Is the fuel priming cycle timed,or should pressurization switch it off.
Also i can't notice the usual pumping noise,maybe cause it's not pushing against any pressure?
colin.

[leslloyd]

Uh!
I said it won't keep running,Duh!
If it kept running would i be here?
colin.

[Andrew426]

Check your oil pressure sensor. When you turn the key, it will prime the fuel system and bring it up to pressure. Then once the oil is pressurized (within 1/2 second of first firing, normally) the oil pressure switch sends signal (via the ECM, of course) to the fuel pump relay to keep the fuel pump running. Bloody good idea really, that way if oil pressure drops the engine stops immediately and doesnt chew its guts out or sieze.

[leslloyd]

Thanks,now that's the first thing i'll check in the morning,will get back to you on this.
cheers
colin

[centy]

Check your oil pressure sensor. When you turn the key, it will prime the fuel system and bring it up to pressure. Then once the oil is pressurized (within 1/2 second of first firing, normally) the oil pressure switch sends signal (via the ECM, of course) to the fuel pump relay to keep the fuel pump running. Bloody good idea really, that way if oil pressure drops the engine stops immediately and doesnt chew its guts out or sieze.

this post is just plain wrong plese disgrard it.

the oil sensor circuit acts as a BACKUP in case the fuel pump relay fails.
This keeps the pump running a few seconds after the car is turned off and can start the pump once oil pressure get up, but ONLY if the relay has FAILED.

i think it is pin 37 and 87 on the fuel pump relay socket, if you short them the pump will start and run as long as you keep the shorted.
i used this to pump 6l out of a vp to start mine when it ran dry.

[leslloyd]

Ok,i'll try that first.But why does the pump just stop pumping as i've only got the fuel going into a can.Theirs no pressuring of the lines to say"hey i've pressurized the fuel rail"now the fuel pump can stop
colin.

[Andrew426]

this post is just plain wrong plese disgrard it.

the oil sensor circuit acts as a BACKUP in case the fuel pump relay fails.
This keeps the pump running a few seconds after the car is turned off and can start the pump once oil pressure get up, but ONLY if the relay has FAILED.

i think it is pin 37 and 87 on the fuel pump relay socket, if you short them the pump will start and run as long as you keep the shorted.
i used this to pump 6l out of a vp to start mine when it ran dry.

What do you mean if the relay fails? if the relay fails - the whole lots ****ed anyway as there is nothing to switch the fuel pump on. Are you suggesting that the fuel pump has two switches wired to it in parallel "just in case" one of them fails?

[centy]

yes the ecm only operates the pump for a couple seconds when you turn the car on. when it starts the pump will operate continuosly.

andrew the fuel pump is operated by a relay. If the relay fails the pump will then get power from the BACKUP circuit which is operated by the oil pressure sensor.
if in dought remove the pump relay from you car and you will notice that it will start only when the oil light has gone off, unless there is still pressure in the lines.
now try it the other way oil sensor disconnected and relay in place and it will start again.
however BOTH go through the fuse so to stop the pump to reduce the pressure you remove the fuse.

if the oil sensor cut out the pump as many people think then when ever you wash down your engine the thing would not start for a couple days.
vn/vp sensors always play up when wet.

[crazybiker]

No they dont. Mine are perfectly fine.

I washed it the other day, and had NO sensor issues.

[leslloyd]

Ok i worked on it all day and have now got pumps working.Only i've forgotten which hose connects were.
And the pin numbers (on the relay)were 30 and 87,this keeps the pump on continuously which is what i wanted to check.
The lower pipe in the engine bay is the fuel under pressure,does it go to the regulator first or the pipe that goes to the back of the injector rail(top pipe).
colin

[centy]

the one that come out from the wall goes to the drivers side of the rail as it is return line.
you can work it out from there.

[leslloyd]

Are you talking of VL here?.Can't work that out.
colin.

[leslloyd]

Yeah clear as mud centy,tell me your a teacher,i'll understand.

Actually i have got it now,i went to carpoint and viewed about 30 VL under-bonnet pics
before one clearly showed,now wait for this,in typical GM logic,the lower hose (pressure)from tank goes to the highest injector rail inlet pipe fitting and the higher of the pipes (2 inches higher)from the tank goes to the lower fitting on the engine(return).
colin