G'day

Got a problem with the carby in my xf. Still need the engine to get me to and from work until the new engine is complete so i need this fixed.
It's started to run really rough at idle. The idle jumps from any where between 500 and 1100 rpm. When you drive it it still pulls like it usually did.

Its lost vacume somewhere. After taking the air cleaner off and plugging up the vacume lines that run to the air cleaner housing i checked the timing and spark plug gap. All that was normal. I then lent on the carby by accedent while i was checking something else i noticed. Then it started to run fine. I took my hand off the top of the carby and it started its rough idle again. i half covered the throat again and it run fine.
I checked all the vacume lines for cracks and dodgy fittings but there all fine. What the hell is causing it?
Could it be a vacume switch somewhere? Its got nothing to do witht he dash's vacume supply. I disconnected that and plugged it up and it still run like s**t.

Any help would e great.

Cheers

sounds to me like the choke has something to do with it. is the choke working when you first start up? check the wiring to the choke and that the butterfly is not sticking etc

The choke works fine. It when it comes off choke that the problem starts.

We found that it have a block idle jet, so off to get a rebuild. Gives me the s**ts when i'm planning to convert to efi.

Cheers

cross your two centre plug leads and give it a few revs. It will backfire through the carby and blow the rubbish out of the idle jet.