gooselogan

New Member

• Mar 28, 2011

• #1

My V8 is playing up again, it will start up, but won't rev and then will hunt for idle and then die.

If I fiddle with the dizzy cap it will then be fine and then when I switch to lpg is runs okay. This first happened on saturday which I first thought was due to lack of fuel which seemed to have solved it when I put some in. But it's just happened again, ran okay once I fiddled with the leads, drove less than 100yards and it started doing it again.

The dizzy cap and rotor arm aren't genuine, which I know is a no no, so I've just bought new gen. ones (just got to wait for them to be delivered). Are these likely to be the problem?

 

W

Wookie

Active Member

• Mar 28, 2011

• #2

When warm does it run fine on lpg?.

 

gooselogan

New Member

• Mar 28, 2011

• #3

It runs fine on lpg, but I can't switch to the lpg unless I rev to 2000 which I can't do. It's done this both times when the car is warm, whether that has anything to do with it?

I just swapped the dizzy cap for another I had and it runs like it did before on petrol, but then the engine is cold now.

Are there any sensors I can unplug when warm or cold to see if it runs any better?


Forgot to say aswell, it's a 3.9efi

 

W

Wookie

Active Member

• Mar 29, 2011

• #4

If it's fine on lpg which takes its readings from the ecu and sensors then it doesn't seem likely that there's anything wrong with the sensors etc.

You could try disconnecting the MAF sensor and checking for holes in the big pipe which connects it to the plenum. This should help to rule out air leaks.

I have an issue on Rover when starting from cold on petrol and this has been traced to the fuel pressure regulator, which is allowing too much petrol through.
If you don't keep the revs up it stalls cos the sensors are all confused.

Really stinks of petrol, is yours the same?

 

gooselogan

New Member

• Mar 29, 2011

• #5

I've checked for air leaks and I did find some loose connections but they haven't made any difference to the running.

I did think that it being fine on lpg would mean that sensors are likely to be okay.

It does run rich on petrol. Is there any way I can test the fuel pressure reg? Or is it a replace and see if it fixes it?

 

W

Wookie

Active Member

• Mar 29, 2011

• #6

It is possible to test the fuel pressure regulator (2.5bar) but I don't think it's a diy job.
It's also in a bloody awkward spot, right at the back of the l/h cylinder head.

I'm still looking for a replacement. Lucas have stopped making them so it'll be an aftermarket job, when I manage to find one.
Seen a couple on fleabay s/hand, but it's pot luck whether it works or not.

Mine was diagnosed (cost £35) by a process of elimination, if all the sensors etc test ok and it's still rich it's the only thing left.
The ecu had reduced injector timing as far as it could and there was still too much petrol.

 

W

Wookie

Active Member

• Mar 29, 2011

• #7

P.S. If you can get to an lpg tuner they can adjust the system to either start on gas or change over at a lower rpm.
Rover changes at 1600rpm for example, and my old VW LT (carb) starts on gas all year round.

 

gooselogan

New Member

• Mar 29, 2011

• #8

I know theres a schrader valve on the fuel rail on mine in the middle on the l/h side. I have connected an old bike pump to it when I was first getting it running and it was just under 2.5 bar. Whether this is accurate or not I don't know.

I think I'm going to go have it plugged in see if there are any codes stored so I can get a more certain idea.

At the moment I just want it starting so I can get to work


Also, do you have the part number for the pressure reg?

 

W

Wookie

Active Member

• Mar 29, 2011

• #9

Good luck with the fault codes/diagnosis.
I don't have a part number unfortunately, as all the numbers are on the bottom and I can't see them even with a mirror.