My 2004 xj8 only starts after about 5 seconds of cranking, especially after a few days of just sitting. Once it warms up and I turn it off, I can start the car again with no problems. I've only had this car for about 4 months and drove it home about 400 miles no issues. I haven't done much to it mechanically speaking. Thanks for the help!

 

Most likely: Losing fuel pressure in the fuel rail after shutdown due to a drippy injector. Guys with more Jag experience than me here tell me you can monitor Miss Pretty's fuel pressure PID with a OBD2 scan tool.

 

Measure fuel pressure when starting-should be at least 55 psi.

 

Yes might be a weak pump after all this time. But change the filter first.
.
.
.

 

Yes thanks for the replies,, I think ill start with the fuel filter first. I forgot to mention it had the check engine light on due to a small evaporative leak, I checked the gas cap and it looks good. Also, when it started giving me problems was when I let the gas get to about 2 gallons in the tank. Today, I put in about 8 gallons and it started right up like nothing ever happened

 

Weight of the fuel will actually boost fuel pressure a little bit. So maybe partially clogged filter, tired fuel pump. I'd replace the filter ASAP and...buy AAA and wait till the fuel pump fails or doesn't meet spec (PID on OBD2 scanner? / gauge on Schraeder fitting on fuel rail?)

Another thing that can happen is if the tank isn't VENTING correctly it can suck a vacuum (oil can) and refuse to let fuel flow. Your CEL for evap problems COULD be a failure to vent versus an unexpected LEAK from the evap system. If vehicle dies on the road and won't restart, try removing the fuel cap, wait 3, and re-try.

I diagnosed that on the side of the road guy with a XJS one time - his motor had simply quit and he'd pulled over. He'd been having problems with it dying randomly for months. Dude was impressed. LOL, so was I.