XJS wont start ??

[fast cars]

Hi , I have a 1996 4.0 XJS, out of the blue it refuses to start, a good mechanic friend has checked for fuel and spark, all present but still not starting. Could it be the alarm system or is there another common fault that causes this, really appreciate some info/advice.

Thanks
Danny

[Straight6DOHC]

I guess it will crank as you say you have spark? If it is security related it won't crank. Usual culprits are crank sensor and coolant temp sensor. I don't thing you get spark if crank sensor is the culprit. The engine might be flooded. Put your foot hard on the throttle - to the floor. Start cranking for 20 seconds then bring your foor up to around 50% open throttle. That should clear a flooded engine.

[fast cars]

Hi , sorry it turns out there is no spark? please do advise Thanks Danny

[louismchuge]

coil?

[Straight6DOHC]

Can the op confirm if the engine is cranking? If it cranks watch the rpm needle on the dash. If it doesn't move or doesn't move to around 150-200rpm, it's likely to be the crank sensor. Did you check for spark on every coil & plug. The car should still start and run with one faulty coil and plug. As said before, I don't think you'll get a spark if it's the crank sensor. You need to give us as much info as possible with these posts as it helps with diagnosis.

[fast cars]

Hi, thanks for the great advice, there is no spark and the engine cranks over at the normal speed, could this then be the sensor you mention? Thanks Danny

[Straight6DOHC]

Hi Danny, well, it could be the crank sensor, but, it gets expensive just to throw parts at the car. If the crank sensor was completely goosed I wouldn't expect rev counter to read 150-200rpm. A dodgy coolant temp sensor could tell the ecu not to fire the engine and a dodgy MAF might be able to do the same. Try reading through this website for other likely causes http://www.watchet.dolphins.btinternet.co.uk/8jags...
It would be benificial to get any stored codes read if you know someone with a scanner and also try to get sensor information and see if they correlate with acceptable values. (the MAF reading should read 10 times less than the normal value so is probably around 0.05g/s?)
You could also check the ecu for corrosion.
I've just remembered you have an xjs so bear in mind the website deals with xj6 -it should still help though.