I have been everyday driving my 1986 XJ6 for about a year now. It ran o.k. But in the last two weeks it was taking a long time to start and I had to pedal the throttle to keep it running. ( It stalled at anything below 1000 rpm's ). But now It starts almost instantaneously then only runs about 5 sec's then dies. It runs for a shorter period time with each successive start attempt ( 4 sec's 3 sec's etc ) any advice would be appreciated. Thank you. I love this forum

 

The 'could be' list might get a little long.

I'd begin with something really easy like checking the ducting between the air flow meter and the throttle body. Is it secure? Not split/broken/leaking?

My gut feeling, though, is that you have a problem with the fuel pump circuit. The circuit has two modes, start and run. Perhaps the 'run' branch of the circuit is inoperative?

If you have a test light or meter we can walk you thru some diagnostics.

Or you can bypass the fuel pump relay so the pump runs at all times and see if the problem goes away or changes. I can give details on that if you need them

Cheers
DD