I read the threads and have done several things. My 99 XJ8 just won't stay running for more than a few seconds. It started a month ago when I moved it from outside the garage in. Did not start again. Thought it might be a cylinder wash. Pulled and replaced all plugs with a dab of oil inserted into cylinder. Checked fuel pressure, holding at 42.
Check all connections. swapped relays under headlamp. Finally got it to start but only ran for 3-4 seconds. Kept charger on battery, which is new. Kept trying every few days. Last week it started staying running longer, like the ecm was learning something. Today it ran for may 7-8 seconds.
BTW if I really pound on the accelerator while starting, it will act ugly but cough and sputter for a few more seconds before dying.

 

CEL?

Everything but gas should give you some indication OBDII code clue as to the problem. Reseat or swap the relays in the front right enclosure. They are all the same. Pull the ECM and reseat it.

DISCONNECT THE BATTERY BEFORE DOING THE ABOVE.

 

Reseated the relays. Replaced the fuel filter just in case. Just seems like its' the fuel supply. Lost my 7-8 second run time after disconnecting the battery and reseating the relays.

Codes currently displaying are P1637, P1000, P0112, P0102.

 

Thanks to all who helped. XJ8 running great now. At the end, it may have been numerous connections which I cleaned and reseated.

Now back to my 96 vanden plas