Thread: Suspected Fuel Pump issue

Hi I think they have a anti drain back valve in the pump....it's not a real hard job to fit a v6 Holden replacement / Bosch pump..but bee- utey ( member) will come on here and he will definitely will be able to help you...Gary

There's a Schraeder valve on the fuel rail on the post-95 V8s, not so sure about the early ones. Bee utey is definitely top notch with these.

Thanks. There was a post a while back with the title 'air in the fuel line' that I posted on earlier today. The symptoms with that one seem pretty similar to mine. Not sure what the outcome with that was, but it has lead me to think that maybe it isn't the fuel pump.

Originally Posted by SamC

Thanks. There was a post a while back with the title 'air in the fuel line' that I posted on earlier today. The symptoms with that one seem pretty similar to mine. Not sure what the outcome with that was, but it has lead me to think that maybe it isn't the fuel pump.

The other thread is about a diesel which doesn't run an in-tank pump. The diesel runs a lift pump attached to the engine.


Your pump pressure can be measured at the fuel rail so long as there's a schrader (tyre type) valve on the fuel rail. You will need a screw-on pressure gauge otherwise fuel may spray everywhere. The important thing with EFI fuel pumps as Gary S11 posted is the check valve in the pump that holds line pressure after it is turned off. So if the pressure holds after turning the engine off the pump isn't the problem.

Now as to your actual problem, have you tried using the accelerator on start-up? It may be just the idle speed controller (stepper) sticking closed.

Another possibility is your ignition switch is faulty, if the engine stops running as soon as you release the key.

Thanks for replying bee Utey.

In relation to the ignition and accelerator - I would only need to turn the ignition once and then if I kept pressing the accelerator up and down in would keep it revving but never really firing if that makes sense. The revs would go from near zero to 1000 and back as long as i kept pressing the accelerator up and down (I couldn't just hold it down). As soon as I stopped it would die.

When i was last driving it around, before I started her up yesterday, it stalled 4 times whilst driving. Twice after taking off at lights, once just driving along and once driving down a hill and turning off. The car just lost power in all instances. It was hard to start perhaps 5 times. Each time I would keep trying to start it and it would rev up and then die straight away (regardless of whether I kept the key turned or not).

The most consistent thing was every time it restarted (normally after about 5 - 7 minutes) it would rev high and then settle and drive perfectly. At all other times it idles fine and is powerful when it drives.

Thanks again for your help bee Utey, any help you can give is greatly appreciated.

Well it sounds like you're getting enrichment every time you press the accelerator (just like a carby has an accelerator pump) and it's running just on that. I'm not really an EFI expert but that sort of thing could come from low fuel pressure, a dodgy throttle position sender (TPS) or air flow meter (MAF). You need someone to plug it in to a tester of some sort.

Hi Sam C,

Agree with Bee utey except for the Dodgy Throttle position Sensor (TPS). I have just replaced my TPS after diagnosing it's failure. The v8 will start and idle easily even when the TPS fails.

Hope this helps eliminate one suspect.. Good luck

Excellent, thanks again. That gives me something to look at.

If it is a fuel pressure issue are there many separate parts that could be leading to the problem? My first thought is fuel pump, fuel filter, fuel injectors, fuel pressure regulator, and all the others I don't know of... Are some more likely to be the problem than others?

If it is the Maf, is it just the single part (the Maf sensor) that needs to be replaced to ascertain whether it is problem or not?

I'll take it in somewhere and post back what the problem was, just nice to have an idea when I'm talking to them about what the problem might be so I don't end up walking out with a whole lot of parts that I don't need.

Cheers