I recently purchased a 1985 12 cylinder XJS from a friend and love the car. However, last week it didn't want to start - it would sort of idle roughly for a short interval, but die as soon as I pressed the gas pedal. After multiple tries it fired up and ran fine, but quit while I was driving to work (near a parking space, fortunately). Multiple tries could't get it started again, with either idle or full pedal on the throttle, so I took a taxi to work. That evening, it started fine and I drove it home.

Over the weekend, it started and ran fine, so I thought "water in the gas" since I drive it rarely. I filled it up and added some Prestone "dry-gas" stuff and considered the problem solved.

Yesterday it brought me to work, but on the way home died while driving. Again, it would "sort of" idle roughly a few seconds and die quickly. I went to dinner and a couple of hours later it started fine and got me almost home before repeating its problem. Again a couple of hours later, it started fine and got me home. The previous owner, who is a good friend, says he never had any problems. Help!

P.S. Does anyone have a good XJS mechanic to recommend in the NVA/Springfield area?

Submitted by NW41-38077J on Sat, 05/20/2006 - 04:47

Check easy things first. When was the last time you changed the fuel filter? Don't forget to clean the filter in the surge tank too. The one in the surge tank will clog with dirt and starve the engine. When the engine is turned off the dirt falls off and the engine runs for a while until the dirt clogs the filter again. You have to drain the fuel tank by a pitcock under the surge tank before you open the surge tank up. Ray Papineau JDRC/NWA
1990 XJS V-12 CONV.
1990 XJS V-12 COUPE
1988 XJS V-12 CAB.

Submitted by congerlang@aol.com on Sat, 03/04/2006 - 14:51

I had an XJ12C and subsequently an XJ6C in the Wash., D.C. area, both of which seemed to occasionaly have symptoms similar to yours. As I loved the look of the pillarless hardtop aspect of both those cars, I mostly drove them in the spring, summer and fall with all the windows down. After a "died in the middle of nowhere" situation, in about an hour they would start right up and run normal. I finally realized that this only happened when it was above 80 degrees and the A/C was off...and we know how hot it gets under the bonnet.
There is an A/C cooling cylinder around the gas line prior to reaching the carburetors; having the A/C off most of the time (until I figured it out) caused a form of vapor lock even while driving the cars. Maybe your friend drove the car most of the time with the A/C on and didn't experience the problem while maybe you have it off when this occurs. Good luck.

Submitted by silver007@shaw.ca on Thu, 02/23/2006 - 00:31

Art Dickenson.
1983 XJS GT "Silver"
Pacific Jaguar.ca

I had the same symptons with my 83 S turned out a good used ECU fixed my problem, another time at the track the car died on track, managed to restart just, turned out this time a wire in the V valley close to the ignition amplifier was broken , managed to start probably by the spark jumping, found the problem when I got home.
Good Luck, Art

Submitted by bonnettoboot@e… on Wed, 02/22/2006 - 23:51

It sounds like a typical fuel starvation problem and most likely to be a fuel pump, you have to listen in the boot to see if it is working when the engine stops. Ideally you should put a pressure gauge on it or taqke it to a GOOD MECHANIC. Jaguar affectionado and etc.

Submitted by dougdwyer@adel… on Wed, 02/22/2006 - 23:37

Kurt, there are many possible causes....a wiring or relay problem, faulty ignition coil or ignition module, fuel delivery problem, and on and on....

I don't know what your experience level is or what tools you have, but, next time it dies, try to narrow it down to lack of fuel or lack of spark

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

Submitted by rpetrey@mindsp… on Wed, 02/22/2006 - 22:17

I had an XJ6 1986 model series III that did the same thing. My case turned out to be a bad ignition coil that would over heat. My coil did not have the factory balast resister on it, so I replaced the Lucas (Prince of Darkness) coil about every 3 months, I finlaly got smart and bought an aftermarker Ford racing coil. That stayed in the car for several years and I sold the car with it still in it. But that was just my case. At that time I was buying Silver colored Lucas coils for $27.00 each. You think I could have found a balast resister to put on it... and then that might not have fixed it.