VR Commodore fuel pump

[blackbird]

Hi Guys, Need help with VR Commodore fuel pump, I don't think it is working, I have disconnected the fuel filter from the main fuel line when you turn the car over & pump the accelerator there is no fuel coming out, does this sound like it could be the fuel pump, the fuses seem to be all OK.
Thanks
BB

[Matty89]

can u hear the buzzing sound when u put the ignition on?

[RUN415]

Turn your ignition to the reds and listen carefully for the 2 second whirr of the fuel pump - helps to be somewhere a bit quiet.
If there is no 2 sec whirr it WILL NOT start.
One trick, if there is no whirr is to bang the bottom of the fuel tank with a rubber mallet (gently?) - may help if someone turns on the ignish while you do it but not vital.
The next step is to check that it's getting power at the plug near the tank using a test light.
If it needs replacing, buy the best pump you can.

[blackbird]

no noise at all

[RUN415]

Ok...that's bad.
I'd be checking for power where I said...which, if there's power, means all your fuses and relays are prob ok and it's likely a pump failure.
A pump failure means $80-100 and a messy hour or two working under the car inhaling the sweet scent of unleaded. :-)
It's not a hard job (3 hoses 5 bolts + 2 hoses for the filter which must also be done) but it can be quite irritating getting that stoopid pump assembly in and out.
Hope your tank ain't full!

You could also try checking the FP relay by substitution.
I suggest reading up on all the options - try putting 'FUEL PUMP' into the forum search?

[RUN415]

My VS Exec has a four pin plug joining to the round outer fuel pump assembly right by the fuel tank...just above the rear axle.
When testing with a light I only get power at two of the pins...which I assume is normal.
With the clip on the plug to the top I get:
Pin 1 - nuffin
Pin 2 - Low (dim) continuous current. (possibly for the fuel gauge???)
Pin 3 - nuffin
Pin 4 - 12 volts for 2 secs only for the prime (on start) (So position the test light so you can bend down and see it as you turn on the reds.)

Note: Once the car is running the power comes from a circuit dependent on oil pressure (or sumthing) to stop it from running during/after an accident.

[blackbird]

Thanks for all your help.

Have tested the pins with a testing light only one appears to have power, I would think this would be for the fuel guage as the guage is working. Any ideas on where to next?

[wortus]

I'd be removing the fuel pump relay, check for power on the relay base, then bridge out the connections on the base that correspond to the relay's N/O contacts. This will if 12V is present apply 12V to the pump all the time. You can then check out the circuit to see if there is voltage at the pump end. To try and kick start the fuel pump by banging on the bottom of the tank you really need to have 12V on the pump while your doing it so give that a try if after bridging the relay and confirming 12V at the pump end it does not run. You need to eliminate the pump and it's circuit and if they are OK and it's not priming for 2 seconds then it might be the ECU.

[RUN415]

Yep, concur...DO what wortus said...helped me find a problem with my fuel pump power plug (to the FP assembly) which had me totally baffled.
It wasn't connecting properly...hence intermittent failures...which is easy to blame on the fuel pump.

On my VS exec, I bridged out pins/slot 3 + 5 on the relay base (where you plug the relay into)...easy as...it was the two big slots right next to each other. (Check the circuit diagram on your relay!?)
This gives you constant power to the fuel pump...even with the ignition off.
There should be good power (not dim with a test light) to pin 4 of the power lead that plugs into the fuel tank.
I could turn my pump on and off with the slightest touch, push or wriggle of that power lead - which I suspect wasn't earthing properly...and still isn't :-(

Anyway, thanks wortus, saved me a heap of hassle...and a 100 bucks! :-)