Hello,
I have let 2004 XJ8 sit outdoors for at least a year. It ran fine when I parked it. I am assuming with the bad gas these days that something might be clogged with bad gas. I put in some new gas but would not start. Does anybody know what my problem and fix might be?
Thanks,
Holden
holdenwallace@hotmail.com
If it’s stale gas, you might have to siphon/pump it out and put in fresh Or, first, try this (easier) if you only have a few gallons in the tank: (1) add 3-5 gallons of fresh gas + (2) bottle of Heet (water remover) + (3) bottle of “Star Tron”, which is the only product I have seen that claims it actually “renews” (or “rejuvenates”, or some such term) year-old gas. I’d shake the tank a bit and let it sit for a couple of days, then give it a start. Keep in mind that you may have to crank it awhile before the “good” stuff gets up to the injectors.
Try with starting spray and once it runs, fingers crossed, you should drive it and put fresh fuel in and run some of that through as well before you let it cool down.
Are you sure you don’t have any other issues like a weak battery? are there any DTC’s? check for full voltage and if no start, you should check the fuel pressure.
Does it make any noise like it is firing or trying to start?
Speaking of which, I just learned, after all these years, on the XJS forum this week that our facelift models don’t have a Schroeder valve on the fuel rail to check fuel pressure at. 
Hopefully the X-308 engines do … 
(MotorUpman?)