i have 98 XK8 60k on the clock.
it starts very easily one min then i can leave it and all of a sudden i come to start it again and it wont fire up just turns over. i can leave it a day or 2 and it will start again... can anyone help me please???

 

Welcome to the forum markhoof,

I'd investigate fuel delivery pressure (failing fuel pump/blocked filter) but there's also the possibility of a faulty ECT (Engine Coolant Temperature) sensor giving a false output to the ECM (Engine Control Module) from a warmed engine.

When you get a minute, please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

I would bet good money on it being an earthing problem. I kid you not I had a (cough) BMW that would not start unless you slammed the door shut, that got me some odd looks. I checked all the electrical cables and they were tight. But I took them off the battery anyway. Glass papered them down till they were shiny. Put them back on tight. Job done. Never had a problem the whole time I had the car.

My XKR went in for some repair work. They put on a brand new earthing strap under the car. I pulled up at some road works. Turned off the engine. Would not start! It spent 3 days by the side of the road till I could get a recovery to my local garage. Turns out the lad had not cleaned the area before stick on the new strap. Disconnect it. Cleaned it. Started first time.

Here you go , have a read. https://www.jaguarforum.com/showthre...=1#post1064865

 

http://www.jagrepair.com/DTCforms/X103_U_DTC.pdf

 

I have had a DTC ran on my xk8 98 60K miles and a P1260 and a U1135 came up. I found 2 sites that gave me info on these codes.
The U1135 relates to Driver Seat Control Module. which could mean:-
1. Ignition switch to BPM switched ground circuit(s) failed.
2. BPM SCP Key Status error.
3. BPM SCP network fault
4. SCP network fault
and this is why i get my P1260 security input malfunction code. which relates to the Key Transponder Module failure. / and or KTM to ECM circuit short circuit, high resistance or open circuit.
This I hope is the cause of my start no start problem.

So frankc could well be correct on a bad Ground/Earth.

http://www.jagrepair.com/DTCforms/X103_U_DTC.pdf this is the site for the U codes.

 

I changed the transponder antenna coil, going to try hard boot tonight,
been told possible transponder module failure, maybe a ground (earth) problem,
records a P1260 which is a communication problem, and a u1135. At my whits end with this car!!!
Went from occasional no start but crank to no start but crank.

Anyway if don't start.... having it towed to a garage that deals in jags.

I know if its the module I will need all new keys and it reprogramming.
Trouble is i need to get car to a reprogramming place which is near Harrisburg 2hrs away if i have to replace transponder module.
Does anyone know anyone that can program a transponder without it connected to car?
Or if that is possible?

Still not sure if its Module. Will update but all suggestions welcome.

 

It turns over ? I mean the engine cranks, right ? Maybe someone will chime in here, but I didn't think the engine would crank over if the key / transponder was the problem. It could be
something simpler - maybe a problem related to heat, since it will start if it sits a day.

 

Yes the car turns over. I had seen a post somewhere, where someone posted a heat sensor problem. Could this if it deteriorated over time eventually stop the car from starting?
Makes sense if so?
But it did show a P1260 diagnosis. And a u1135 failure.
which translated to a communication failure to the engine management.

 

Ok 700 dollars later and a new fuel pump, transponder ignition switch ring sender, fuel pump relay we finally found the problem.. It was .15 dollar fuel injector relay.
my advice if anyone has same problem switch out all the cheap relay parts first its worth it ...

 

That's why motorcarman always says switch the relays with others before throwing parts at it.