Hey guys, I'm Having some trouble with my XD.

Occasionally the idle drops and is really lumpy, misfiring all the time. At low revs under power it surges, then settles down at higher revs though still misfires. All the while there is a strong smell of fuel fumes present.

The problem comes and goes without warning or a common trigger, and is usually helped by cutting the ignition and re-starting.

I've checked the tune and can't find any problem - the leads are all ok, there is no vaccum or carb leak.

Has anyone experienced this before or have any idea what the problem may be?

Cheers.

Hi, I'm taking a wild guess here, but if you are running on petrol (as opposed to lpg - if on lpg then I've got a different theory!) then I reckon your problem might be to do with fuel float level or maybe leaking float, or buggered needle and seat.

I had a very similar problem in an XA 6 cyl - took me ages to figure it out, but I had a pinhole in the float which would only some of the time fill with fuel, then sink, overload the fuel level, cause staggering etc but also a really bad fuel stink. Open up yer carby, and if the float aint floating, there's your problem. Even if it IS floating, check it vey carefully, also check needle and seat while u are in there... The turning off then on again might be fixing it cos you are using up a bit of fuel in the float bowl, I dunno, or maybe its causing a backfire or high vaccum situation that clears a dirty seat? Anyway, worth a look and cheap to fix if thats your problem...

Cheers mate, I've even been thinking in recent weeks to switch from the old single throat to a twin barrel carb from an XE or XF. I might just do that and give the new one a good going over as you've described before chucking it on. I've moved to the city and am sick of using a manual choke in peak hour traffic! Plus I should be able to expect slightly improved economy with the dual throat setup.

Any thoughts on the carb swap anyone? Past failures or successes? Or does anyone have an EFI 250ci XF donk lying around...

Check for wear in the dizzy shaft, if its bad enough, and the reluctor poles out, it won't deliver the pulse to the ign. module properly causing missfires..etc...
Also check vac advance unit for leaks and working ok.
Also check the mechanical advance is free and working.