I might buy my first XJS (1989). The car has an issue where it doesn't seem to get enough fuel before shifting and then gets too much fuel when idling. Other than that its in excellent shape. I was wondering if anyone has ideas on how to possible troubleshoot this problem.

I was leaning towards changing filters, plugs, and then getting new gas into it.

Thoughts?

Thanks.

 

Air filters will be obvious but would present consistently irrespective of gear change. 100% change the gas, flush it through and change the fuel filter - you may need to do this twice depending on how long its been sat and the degree of crud in the lines. You also fail to mention if its a v12 or I6 but as for plugs and ignition components they seem unlikely culprits without any obvious stumbling / misfire.


Assuming its the v12 I would move onto the AAV - it governs idle speed which should be about 750rpm - this naturally dips (but should quickly return to normal) when you take gear as the transmission engages the engine. Its simple to adjust but also has a penchant for failure. Also if your going to do the ignition do it ALL at once, particularly on an 89 which I believe should have Marelli ignition. Some one else will no doubt chime in.

 

My 89 has Lucas ignition

 

1989xjs,

I've had similar issues with my XJ as well. Were you able to get this resolved?

 

1989 was a transistion year for the ignition. My '89 has the Lucas.

According to the Jaguar Heritage site, XJS's with serial numbers up to 157115 had the Lucas. Beginning with serial Number 157116 they came fitted with the Marelli.


Mark

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Are the throttle butterflies adjusted correctly so that they both open and shut at the same time?