355 VS Clubby - fuel pump issue - HELP

[ScottyDot]

Hi,
My Clubby stopped in the driveway the other day.... realised the fuel pump wasn't running. It's an in tank Walbro 255ltr/min. Ended up changing the oil pressure switch. Now after 2-3 seconds of the key being turned to the on position the fuel pump runs constantly and she winds and won't fire. It's not until a pull the EFI relay that the pump will stop. Fuses all okay. Fuel pump relay getting power. If I bridge the fuel pump relay though it doesn't make the pump work??
Put the old oil pressure switch in - back to no fuel pump at all.
I assume I have a wiring problem on the OEM side - hoping not the ECM.
Has anyone had this problem before? What did you find?

 

[BlackVXGTS]

Have any error codes been set?

https://forums.justcommodores.com.au/threads/checking-error-codes-vr-vs-revised.22307/

 

[Immortality]

When you turn the Key to the on position the PCM is supposed to run the fuel pump a few seconds to ensure the fuel rail is pressurised correctly and the pump should then stop. Once you crank the engine and it starts the oil pressure switch provides power to the fuel pump circuit but the pump should stop when the engine isn't running as there is no oil pressure to activate the oil pressure switch. This is a safety feature. See wiring diagram below. If the pump runs when the engine is not running via the oil pressure switch than most likely that is faulty.

 

[ScottyDot]

Have any error codes been set?

https://forums.justcommodores.com.au/threads/checking-error-codes-vr-vs-revised.22307/

.
The only code I get is 22 - TPS fault... don't think that would make the fuel pump run constantly or not start?
Does the sender unit/pump holder have to have the fibre washers on it? Or it be get a stray earth?

 

[ScottyDot]

When you turn the Key to the on position the PCM is supposed to run the fuel pump a few seconds to ensure the fuel rail is pressurised correctly and the pump should then stop. Once you crank the engine and it starts the oil pressure switch provides power to the fuel pump circuit but the pump should stop when the engine isn't running as there is no oil pressure to activate the oil pressure switch. This is a safety feature. See wiring diagram below. If the pump runs when the engine is not running via the oil pressure switch than most likely that is faulty.

.
I've tried x2 new pressure switches now - still does the same thing - if I put the old oil pressure switch in - I get no prime and no constant pumping.
I'm really starting to think PCM or wiring?

 

[ScottyDot]

When you turn the Key to the on position the PCM is supposed to run the fuel pump a few seconds to ensure the fuel rail is pressurised correctly and the pump should then stop. Once you crank the engine and it starts the oil pressure switch provides power to the fuel pump circuit but the pump should stop when the engine isn't running as there is no oil pressure to activate the oil pressure switch. This is a safety feature. See wiring diagram below. If the pump runs when the engine is not running via the oil pressure switch than most likely that is faulty.

.
That's an awesome diagram though, I'll definitely keep that to future my testing - Thanks

 

[ScottyDot]

With that diagram I have found the signal to the relay is coming out of the PCM, but isn't at the fuel pump relay. I'll start buy rewiring that and see what happens

 

[Deuce]

When you turn the Key to the on position the PCM is supposed to run the fuel pump a few seconds to ensure the fuel rail is pressurised correctly and the pump should then stop. Once you crank the engine and it starts the oil pressure switch provides power to the fuel pump circuit but the pump should stop when the engine isn't running as there is no oil pressure to activate the oil pressure switch. This is a safety feature. See wiring diagram below. If the pump runs when the engine is not running via the oil pressure switch than most likely that is faulty.

There must be a safety override on this. I removed my oil pressure switch and drove ~30km across town and back a few years ago and it went fine. It would have easily drained the fuel lines 20times over if the pump didn't keep them pressurised.

 

[ScottyDot]

So update, with the diagram - I worked out that most of my relays aren't in the marked locations - so I then found the pump relay was no good. Replace it and my prime cycle worked. Then found a bent pin at the old pressure sensor - straightened and refitted - no constant pumping -all sorted

 

[Immortality]

There must be a safety override on this. I removed my oil pressure switch and drove ~30km across town and back a few years ago and it went fine. It would have easily drained the fuel lines 20times over if the pump didn't keep them pressurised.

VR may be wired slightly different.