Hi wondering if anybody can give me any advice, my series 3 XJ6 is difficult to start when warm it takes a lot of cranking to start and seems to have a slight misfire. Starts first turn of the key when cold was wondering if head gasket is on its way out.

Thanks Craig

 

Craig,

Welcome to the Forums. When time permits, please do an Intro in the New Members Area.

That list is looooong, and covered in great detail throughout this section.

Always the basics first with me:

When its hard to start:

Is there spark?
Is that spark a Fat Blue Spark, or a washed out excuse?
Once you tell us, we can move to the suspects.

Is there fuel at the rail?
Quicky bypass. When its hot (hard to start as you say), place the gear select in "D", now go for start, it want start clearly, its in "D", BUT, the fuel pump will run, and pump some fresh fuel to the front. Release the key, retu4n the select lever to "P", try the Start again. If its better, you are onto the culprit. It its NO different, one more tick on that long list.

How old are the spark plugs, HT leads, Cap, Rotor. All those things can add up to a stubborn engine in any car.

It is a long process, and working quietly, systematically is the only way.

A few beers will do no harm, for you, not the car.

Is there fuel?

 

Forgot, it happens.

I am not sure of the importance of the CTS (Coolant Temp Sensor), located on the water rail, 3rd one from the front I THINK????

On my usual engine the V12, that sensor is an engine killer, flat out, so maybe it is also on the 1/2 size engine. Thet go flaky, and can be OK Cold, but hissy when warm to hot. Nothing special at all. Standard Bosch unit, the part Number ends in .......026, and Commodore etc use the same sensor, about $30 that last time I wanted one.

Doug will come along when he has had his morning coffees, and the time zones align better.

 

Assuming you have a 4.2 fuel injected model and not the 3.4 running on carburettors....

I agree with Grant that the CTS is a good jumping-off point. In your shoes I'd get the engine warmed up, stop engine, and unplug the sensor. Now take a paperclip and jumper the terminals inside the connector. Now start the engine. Any change?

If no fat blue spark as Grant mentions the coil and ignition module are other things to check. Both prone to failure, both more likely to give trouble after absorbing engine heat. More on these when/if needed.

Are the spark plugs black? That would be an important clue.

Just begin with what Grant has suggested and we'll go from there.

Cheers
DD

 

Thanks for the info will check tomorrow, i have only had the car for 7 months all the paper work i got with the car and a lot of very expensive repair bills over the last year it has had new fuel pump, new injectors, plugs leads ,coil and reconditioned distributor, and a second hand injection harness . will check the temp sensor first then if no luck will check fuel and spark.

Craig

 

Tried jumping the terminals on the temp sensor still no go put it in D and turned the ignition to charge the fuel rail still no go will check the spark and plugs tomorrow, if i switch it off when hot and try to start straight away it will fire no problem but if i leave it for 5 - 10 mins to start till i turn it over and over.

Craig

 

Goodo.

2 things ticked off.

That replacement list is long and reads like someone throwing parts at it to try and fix this same issue, scary.

One thing at a time, thats the only way.

 

Well after a few hot 40 + days and Christmas I got back to checking the hot starting problem, removed the plugs they were all sooted up, I did a quick compression test all good there I then connected a plug and turned the engine over and the spark was very weak.
I have ordered new plugs and coil and will put them in when I get back from holidays and hopefully that will cure my problems.
Thankyou to all who sent me advice on what might be the problem, will keep you posted when I have the parts fitted.

Craig

 

An item mentioned by Doug - but it bears repeating - which can cause difficult or no starting when hot: the ignition module in the amplifier (mounted to the front end of the engine block). The module typically fails with heat, while allowing good cold starts. This is a failure particularly prevalent in the V12 but it also happens on the 6 cylinder.
The module is a GM/Delco part, Delco 1906, and it is very easily replaced - but insist on a genuine, not aftermarket module. They are very readily available.

 

I Solved my hot start issues by replacing with a Pertronic distributor. It has the amp built-in, but leave the old amp in place or block the mounting holes. If not you get unmetered air.

 

I have now also ordered a new ignition module just to be on the safe side will fit all the parts when i return from holidays. Will let you know in a couple of weeks when i get back and fit the parts.

 

Today i fitted the new plugs coil and ignition amplifier to the Jag and i am happy to say it is now purring like a kitten. Took it for a drive to get up to temp and left it for 5 mins and it restarted first turn of the key, i again stopped and started it several time while in had it out of it and it started again no problem.
Thank you to all who have given me advice to cure my hot starting problems, was not too expensive $220 sorted it and i am now enjoying driving it a lot more.

Craig

 

Congratulations buddy