Greetings from darkest Wales, I have a 1994 Jaguar Sovereign 4.0 lt which I am currently considering kicking to death. it's normally a great car with only 105000 on the clock but now it's messing with my head. At motorway speeds, after about 10 minutes driving the engine suddenly dies and will not restart for at least 15 minutes. I tested the Crankshaft sensor, Distributor cap and rotor arm and changed the coil but still once it gets hot it shuts down, even when idling. is it possible that the temp sensor which controls the engine electric fans is causing the shutting down of the ignition. Any suggestions (apart from an oily rag and a box of matches)

 

First (cheap) try is replace fuel filter, located just ahead of rear left wheel under car.

Also, on a 1994 car, a faulty oxygen sensor relay can cause the engine to quit. It is one of the group on the bulkhead, check archives or Haynes for actual location on a RHD car.

If no go, my money would be on the fuel pump giving out.

HTH

Larry

 

Thanks for that Larry, my last XJ40 had a dodgy pump but it would splutter before it engine died whereas this one is instant, which points to electrical. As soon as it stops raining I'll swap the relays and give it a go.
Chris

 

Hi makula,

I like Larry's theory about a relay misbehaving when it gets hot given the instant and also his recommendation to replace the fuel filter. You don't mention how long it has been since you did a good tuneup - filters, plugs, plug wires, clean the ground points, etc., but problems like yours are often due to a combination of components operating out of specification. Ensuring that the normal tuneup items are all OK will at least rule them out as contributing suspects.

Before I offer some crazy theories, can you please tell us:

1. Is the car typically more difficult to start when the engine is hot?

2. Are there any indications that the engine is running rich?

3. By any chance is your transmission fluid low?

4. How did you test the crankshaft position sensor? That seems like a prime suspect.


Cheers,

Don

 

Thanks for that Don I'll give that a go but I had no trouble starting when hot and if I let it idle for 15 min it still dies so I would have thought that would eliminate the gearbox. My biggest problem is that I'm getting old and knackered so it's probably time to move it on, Thanks for your input
Chris

 

Hey we're all old and knackered so that's no excuse

Larry

 

Chris,

Ditto on Larry's reply - I'm old and knackered too!

Please don't give up just yet - I do have some ideas, but you still haven't answered two of my questions:

2. Are there any indications the engine is running rich?

4. How did you test the crankshaft position sensor? As far as I know, there is no reliable test for a sensor that has developed intermittent failure.

Cheers,

Don

 

Whoa! what happened to being nice to old people?
Anyway, I did an impedance test on the Crank sensor which gave me 13000 ohms but it dies so quickly that there is no way of checking when it's hot. it does need new plugs and dizzy cap which I will get once I've shifted one of my paintings (retirement and poverty are good bedfellows) and I will update once I've done that, Thanks again

 

Hey my comment wasn't meant as a nastygram - I really am old too

Larry

 

I am typing this with the Idiot's Bucket of Shame over my head. My old Headmaster once said of me 'will not listen and resents being spoken to!' and the old git was right! At the beginning of this lengthy saga you recommended that the crankshaft sensor was the favourite culprit; did I listen? did I hell. 50 years as a Fitter meant that I knew better and if it wasn't for the nice AA man with his magic freezing spray I would have continued down the dead end of cooling fans etc.
Anyway I finally purchased a new sensor (£30!! from Jagspares International) fitted it and voila!! the beast lives again!! Why I didn't listen and try this first only confirms my nomination as Mammary Gland of the month.
Thanks again Lawerence, and remember to anyone else who is reading this, when the man speaks LISTEN!

 

Hey, dai yawn boy bach!

If it's any consolation, MY headmaster once told my (infuriated) father
after I missed an exam and went fishing instead, (opening day of trout season)

"You do realise that someone has to be a dustman, don't you?"

 

Diolch-yn-fawr. O wise one