Hi, i have a 1989 XJS V12 that is difficult to start after being left for 4-5 days. To start i need to turn the ignition on 20-30 times without engaging starter to help get fuel to engine i suspect and then engage the starter 3-5 times before engine begins to fire but not start, after about 6-8 times it starts. Once started she runs great and starts nicely until left again. Needed to install powerpoint so i can run a trickle charger to charge my battery. It is very annoying!!. I have had fuel pressure tested by mechanic and was ok. recently replaced fuel pump and it seemed to improve the problem for about 2 weeks (not fixed) but it is now behaving the same as it did with the old pump. Any information/ideas on what i can do to determine what the problem is or to fix it would be greatly appreciated

 

Clearly the fuel pressure is bleeding off when the car sits. Does your car have dual fuel pressure regulators on the fuel rail? My 1992 V12 sedan did, but there are differences between the XJS and Series 3 cars. I'd start by replacing both (if applicable) of those and go from there.

The Series 3 had a check valve in the boot fuel plumbing, but I think that was because it was a dual tank car, the XJS has a different tank and plumbing arrangement. Does your car have an in-tank pump or external?

If you want, all the parts diagrams are here: http://www.jaguarclassicparts.com

 

Whenever the key is is turned "on" the fuel pump should run for 2-3 seconds to pressurize/prime the fuel rail. I suspect this function is not working on your car...or not working consistantly. Even if the system is fully depressurized it should only take a couple "key on" cycles to build up pressure a gain.

You should be able to hear the pump run from the driver's seat if you listen carefully. Do you? If not, post back

Or, have a helper turn the key on a few times while you listen for the pump to hum at the rear of the car. (The pump is locatd behind the spare tire)

Cheers
DD

 

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I've moved this thread to the XJS section for better help.

 

Thanks and yes it does have two and that is pretty much where we were at. Only thing that held us back was the fact that once started it runs really nicely which didn't match the reported symptoms of a dodgey regulator