Vr v6 hesitating - fuel pressure?

[semi]

Hey guys,

I have a vr v6, and it's running fairly badly at the moment. Idle is pretty rough, and when it's running it hesitates under load. It usually drives ok for a couple of minutes then starts to hesitate badly-making me think it's a problem with low fuel pressure.

I connected a gauge up to a tee, and when the key is turned on, it doesn't seem to pressurise much at all (needle is pretty much at zero). Running, it sits at about 200 kPa, and spikes to about 250-275 when you give the throttle a little stab. Taking the vacuum off the regulator, the pressure jumps to about 300 kPa, which is what I'd expect, but I don't know if it's correct.

My pressures are a little lower than what my manual states, and which is 240-260 idling (I get about 200) and it drops to zero very quickly after its switched off, and doesn't really pressurize much at all when you switch the key on, where the manual says it should be 260-280. I can't figure out what would stop it from pressurising before being switched on, unless it was a faulty pressure regulator (which is fairly new, and seems to work), or a leaking injector.

Any ideas? Would a leaking injector, dodgy pump or anything else cause these issues?
Thanks
Sam

 

[semi]

Posting this as much as a record for me, as to asking for help;
Removed the injectors, with the whole fuel rail, and pressures seemed to stay fairly high. Put them back on, and they stayed ok, but then I started the car, and now can't get fuel pressure to stay with the engine off.

I'm guessing this shouldn't be happening, and there's a problem with one or more injectors?

 

[VR38]

Sounds like the pump is shot from the test, repeat the test and clamp off the return line first, retest and clamp off the pump feed line to narrow it down to either pump or regulator.

 

[VR38]

FYI with both ends clamped off and you still loose pressure then you have some badly leaking injectors.

 

[semi]

Not sure why, but its holding pressure fine now. Not sure why it did it before, I think it might be because of how I was measuring.

Problem is ATM that the fuel pressure seems to be dropping a bit as the car revs, and is a little low at idle.
Haven't checked the pressure with it driving, but I think it might drop a bit and cause some of the issues I'm having.

 

[VR38]

Fuel pressure will vary with manifold vacuum if you have the reg connected.

 

[semi]

I know, but should it increase with revs?

 

[VR38]

Manifold vac changes with revs AND engine load.

 

[semi]

Should it decrease or increase though?

 

[VR38]

both, depends on engine load and rpm.