VT Commodore Fuel Pressure!

[chief18]

We have a VT Commodore at work, as soon as you turn the engine off, it looses all fuel pressure.

It's not the fuel pump, it's not the pressure reg, injectors or rail. Basically the only possible places for it to go, it's not ha ha.

Anyone had this problem before?

[jazza15]

You may have the same propblem as VNSS and probably me.
Have you replaced your fuel pump before, because VNSS came to the conclusion that his fuel pump did not have a check valve or it had failed, causing this pressure loss and hard start.
He installed an external check valve to fix the problem, but I am most likely going to replace the whole pump so there is no chance of any possible restiction issues with an external check valve.
The thread was called something like "hard start doing my head in" use those key words and you will probably find it.
Basically, a cheap replacement fuel pump and sender is the cause of the problem i think, if it the cause of yours, go with a reputable brand.

[chief18]

Nah mate, not the fuel pump.

We've crimped the return line (not pressure reg), removed the vac line (not the pressure reg diapgragm), crimped the inlet line (not the fuel pump), and cleaned and tested the inectors (not the injectors).

If it was the fuel rail, you'd hear, and smell it.

[delcowizzid]

maybe yo arnt crimping the lines shut fully

[chief18]

Yeah, we've concidered that..ha ha, will let you's know what we work out.

Keep the thoughts coming!

[jazza15]

maybe yo arnt crimping the lines shut fully

But Chief, have you or someone else changed the fuel pump before?
Otherwise yeah, let us know how you go, because I will be fair disapointed if this doesn't solve my problem.

[chief18]

Not to sure about the pump being replaced, but we've come to the conclusion it must be the pressure regulator, because upon crimping the return line with engine running the fuel pressure should increase, and it isn't. There for we must not be crimping it tight enough, meaning fuel is being allowed through the pressure regulator.

The reason it is so hard to crimp, is because it's not just a single hose, but actually a hose with a hose over it as insulation. Even with pliers, multi grips even locked dead tight we cannot close it off.

Anyway the car has left the workshop unfixed as the person who was buying it has changed their mind.

As for your problem jazza15, if you suspect your pump, or check valve, have someone crimp the inlet line, switch the motor off, keep the line crimped and then start it. Once it starts release the crimp of course. If it starts easy, you've found the problem.