I would first check for fuel supply and then spark at the plugs. If you have gone to start the car with a low battery before you recharged it it may have flooded the engine. If it has flooded just keep the throttle on the floor while cranking until it starts. If engine is flooded it will often crank faster than normal due to oil wash in the cylinders .

Remember check for spark at the plugs
Can you then SMELL FUEL ?
IF not check Pump circuit.
Was the car kept out in the rain / damp ? if so check for good spark

My 6.0L has not been started since last October but am sure it will fire up with no problems in March.

 

Agree with 540, could be flooding caused by cold/weak spark, especially in the winter months if stood for a while . I'd take the plugs out first, check if they are wet with fuel and blackened with soot. Wipe them, wire brush them clean, check gap if you have feeler gauge and refit (if you have a gas hob, warm the spark ends for 5 minutes).
Good luck.

 

Hi

As others have said, Any petrol engine needs spark and fuel to fire. Check for both and report back with which is missing.

On the 4.0 litre (don't know about the V12) if you have neither spark and fuel then that points to the CPS sensor which sends a signal to the ecu to run the fuel pump and the ignition sparks

Regards

Chris

 

Hi Chris

Sorry to be a bit thick!! but where is the CPS sensor situated. I have a 93 XJS 4.0 conv. that will not start!

Regards

Gary

 

If it is like the 3.6 there is a sensor at the flywheel and one at the crankshaft damper. But consideri g the history I would start with spark plug check and clean too.

 

Many thanks, yes cleaned and checked plugs. Generally cleaned all relay terminals, but still no spark!!

Regards

Gary

 

Hii didnt know if the 3.6 has two?, but the 4.0l has one cps and as stated above is located at the front lowe part of the engine, on a bracket just above the crank.have a look below the cooling fan and you will see the sensor with a cable going from it. thats the cps sensor,remember the symptoms of a faulty cps is both no spark and no fuel. needs both to be missing. this is because the cps sends the signal to the ecu which in turn turns on the spark and fuel pump.regardschris

 

Very many thanks Chris, I will resume my quest!!

Regards

Gary

 

CPS is a bit awkward to get to if you don't know where it is initially. Get a torch in there first to locate it. It'll be held in place by 1 bolt (8mm I think?) and another bolt/clamp securing the wire. If you have a multimeter, try checking the ignition coil too as it's a simple job.
BTW, can you hear your fuel pump energise when turning key to position II ?

 

Thanks just about to start looking!!

Regards

Gary

 

Had similar touble with my 3.6 on & off. After checking all usual ignition & fuel woes my mate who is RAC rescue driver came round & went straight to the ignition amplifier. This, apparently, is fed by very low voltage & needs to be kept spotless. Mine sits on top of radiator cross member. He just pulled it apart, sprayed electronic cleaner in it, wiped it down & it started righ away. I now clean it once a month & no further problems. Dave.

 

HI I don't want to put the cat among the pigeons but toy could have lost compression with cylinder wash which is common with the 4lt. A few drops of engine oil in each plug hole usually does the trick.

Roger

 

Many thanks will give it a go, any help is appreciated.

Regards

Gary

 

Thanks I didn't think of that!

Regards

Gary

 

By the by does anybody know where I can get a list of all the relays and their position, as I am sure it is probably one of them, maybe on the fuel system.

Thanks Gary

 

I have an electrical diagram in pdf form the 1992 4.0 which includes the convertible, shows all the relays and their locations, it may be of help? If you pm me your email I could try and send it to you.
If your fuel pump isn't energising then the fuel pump relay would be a good place to start.

 

Thanks Jonnie, very helpful, it is; ( gary.306simpson@btinternet.com )
Regards

 

Ok. I've sent you 2 types, one is an aj6 management system diagnostics and another is electrical guide. I hope they come through ok, if not, let me know and I'll try again? Have fun reading!

 

Got them, many thanks. That will keep me occupied over the weekend.
very much appreciated. Gary

 

i had a simmiler problem with my 1991 4.0l
but i noticed that the fuel pump wasent running so after checking the pump the pump relay in the boot i found a relay behind the passenger footwell kick plate where the main engine ECU is it was faulty changed it and she now runs as sweet as a nut
mick

 

Many thanks Mick, it is still causing me problems, so will try that.

Regards
Gary

 

its a standard relay only £6.50 from my local spares shop

 

Sorry to bump this thread after so long but I am just wondering what happened in the end?

So many of these threads just peter out and you never get the end of the story.