VR Fuel Pump issues?

[swazi]

G'day People,

I've got myself a busted-arse VR commodore which, as of Saturday, decided to stop going. So far I've had plenty of problems with the cooling system, but it's never failed to start. Anyway, I jumped in in the morning, it fired & then stopped. It'd happily turn over until the cows came home, just wouldn't fire. Shot some aerosol up the air-cleaner, again it fired, but wouldn't keep going. At this point, I was starting to suspect the fuel pump.

I checked the computer with a paperclip in the connector under the dash. It blinked 12 at me repeatedly, so I assume that means all is good there. I swapped the relay and the fuse to the fuel pump, so would assume that's ok. Removed the fuel filter, there was some petrol in it and a small amount leaked from the line at the tank end, but the filter itself didn't seem blocked. I tried turning the engine over with the fuel filter off and got nothing from the tank.

So, I suppose the question is, do you lot think I am on the right track, or barking up the wrong tree? Is there any further reason to think that my problem is or is not the fuel pump itself? Would I be wasting my time & money replacing the pump? And lastly, is such a replacement a feasible job for a mechanical novice such as myself, with limited skills and tools?

Hope someone out here can clear this up for me.. :O)


cheers,
swazi

[hako]

My final check would be to supply power directly to the fuel pump - the hot wire is the violet and black is the earth. If it is the pump, do a search on this forum as there are plenty of posts with step by step instructions. Good Luck.
And welcome to the forum swazi.

[moff_man]

make sure there is 12v at the pump connector round white connector at the pump, also it "prims when the key is turned on so 12v will only be there for 30 sec or so. might need a seccond person. a test light might be ok but a multimeter would be better, and they also come in real handy for other jobs (approx 30bucks for a cheepie, i use a $250 at work but you dont need one that pricy).

next is the pump if the voltages are fine. stright forward job, just dont brake the return line off in the tank, other wise you wont be able to use the last 1/4 of a tank.

[swazi]

thanks for the tips, guys... i'll certainly be careful with the line, i live on that last 1/4 of a tank


cheers,
swazi

[jerzey1234555]

Hey guys im having this problem with my vs statesman, i have done the paperclip test and it came back with 12. I changed the fuel pump 12 months ago after it died so i dont think its that but it doesnt sound like its priming. I dont have a multimeter but i do have a test light and i checked the power going into the pump and it has power just not alot its very dim. Ive changed the relays as well but still no luck, the security light stays off as well so i dont think its that either. Any help would be appreciated

Thanks

[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.

[jerzey1234555]

i checked the power again and its only coming up with power to pin to very dim and no power on the others when turning the ignition on

[RUN415]

Well that could be good news...may mean the fuel pump is ok...which is likely as it's kinda new.
Check the under car wiring for damage?
Double check the relays fuses etc.
Did anything happen the last time you drove it?
The procedure, obviously, is to work your way back from that FP assembly plug to find out why there's no power.
Sorry, I'm not sure of the details as I've never really done it.
Mebbe check that FP relay again...also battery condition and terminals while your there.
Someone else on 'ere should know exactly what to do - good luck :-)

[Brett_jjj]

The fuel pump power is also routed through the oil presssure switch for a backup so the car can be still driven if the ECU fails and cant supply power to the fuel pump. Its not there for switching off the engine in a crash or whatever.

[savage1987]

Always been shady on that. How is it going to keep functioning if the ECU fails, even if there is fuel? Where's the spark coming from? Some sort of limp home mode that is non-dependant on the the ECU?

Makes no sense to me. ECU stuffed = car dead.

[Brett_jjj]

The ECU has a limp home mode so the engine will still run if the ECU fails for whatever reason,thats why its called "limp home mode", and if the ECU fails for whatever reason, and cant supply power to switch the fuel pump relay, the oil pressure switch will still supply the fuel pump with power,(once the oil pressure is up enough to extinguish the oil pressure light on the dash)

EDIT: Heres a bit of info from delcohacking-

" If the ECM has a terminal failure where the software can no longer run, then limp home mode is invoked. This is controlled by a chip called the FMD (fuel modeling device), if the CPU fails to reset the watchdog timer, limp home mode takes over. The spark is controlled by the ignition module. There is a line called bypass mode, when this goes to 5v the ECM takes control of spark timing and dwell, when its grounded the ignition module controls spark timing. In limp home mode the spark is controlled by the ignition module only. In ignition module mode timing is fixed at the base spark advance, this is usually 10deg BTDC. "

The spark just comes from (and is controlled by) the DFI module or ignition module when running in limp home mode.

[savage1987]

I was aware of something like this existing for the Ecotec engines, but this is the first I've heard regarding the early V6. Do the 304 models share the same setup? I'd imagine they probably got it first, being a 'higher-spec' engine?

I guess people who wire in a new higher-amperage fuel pump from scratch interrupt this process in some way or other?

[jerzey1234555]

Just had my car repaired by a mechanic they changed the fuel pump and now it's all fixed apparently it was a faulty unit

[Arrowroot]

make sure there is 12v at the pump connector round white connector at the pump, also it "prims when the key is turned on so 12v will only be there for 30 sec or so. might need a seccond person. a test light might be ok but a multimeter would be better, and they also come in real handy for other jobs (approx 30bucks for a cheepie, i use a $250 at work but you dont need one that pricy).

next is the pump if the voltages are fine. stright forward job, just dont brake the return line off in the tank, other wise you wont be able to use the last 1/4 of a tank.

Mate the return line your talking about, has it got a black rubber line connected to it inside the tank, as thats the thing stopping me getting the old one out, if so how do they disconnect them without braking ??