98 XJ8 4L V8 Auto won`t start.

[Fergus Casey]

Good morning, new to this so here we go, As mentioned above, we are having problems starting the car. The battery was disconnected while the welding underneath was being done, needed more than originally thought so it was disconnected for a few weeks, finished the welding and reconnected the battery, nothing! I do believe the keys were left in the ignition for all or some of the time so is there a particular way needed to get said car going.    

[Wrinkly]

5 hours ago, Fergus Casey said:

Good morning, new to this so here we go, As mentioned above, we are having problems starting the car. The battery was disconnected while the welding underneath was being done, needed more than originally thought so it was disconnected for a few weeks, finished the welding and reconnected the battery, nothing! I do believe the keys were left in the ignition for all or some of the time so is there a particular way needed to get said car going.    

Jaguar are prone to battery going flat. That would be a good starting point in curing your proble.

Best Wishes and Regards, John

[Bill Wood]

Does the engine turn over?

I had a XJ8 that sometimes wouldn't start, although the engine turned over ok. And it 'coughed' sometimes.

I checked everything, including the fuel pressure feed.

The problem turned out to be a fuel pump, it was delivering fuel, but not at the pressure needed. After a new fuel pump, everything worked fine.

 

[LairdScooby]

Have you checked the output from the CPS (Crankshaft Position Sensor) as these can fail suddenly and give simlar symptoms to those you desccribe.

Although i'm not a fan of using Easy Start for generally bad starting engines, it's a useful diagnostic tool here - spray some into the air intake while someone else turns the engine over, if the engine fires it's a fuel related problem. If it doesn't, look at the ignition, particularly the CPS to start with.

They can be changed (certainly on the V6 which is a similar engine except for an extra pair of cylinders at the back of the V8) in situ without a ramp, it's a fiddle and you need patience and cut-proof knuckles but it can be done.

Diagnosis is the thing here, a bit concerned about the key being left in the ignition when the battery was disconnected but that's probably due to the previous car i had. Also have you got a spare key? try that, see if it starts. 😉 😄