99 XJ8 fuel line schrader valve location
 

My beloved Jaguar sputtered and died ( It would crank But not fire up , I have a 5 year old battery that I assume could be a culprit or its gas starved and fuel pump may be faltering ? ( or fuel filter ) but before I have it towed to Repair shop I want to check if the fuel pump is working by cranking it and utilizing the check valve . The relay in the trunk fuse box is clicking ( funny thing there is only one fuel pump relay on the T though ) I charged the battery to do the schrader valve fuel pump test , but will not spring for new battery unless you guys think a weak battery or battery with bad cell or inability to hold charge could be issue that causes fuel pump to underperform . Any help appreciated ...

The schreader valve is located on the left side of the engine next to the cam cover and just in front of the first fuel injector on the left bank. Drivers side US passenger side UK
It should have a small screw on cap.
Turn the ignition key to the on position and wait five seconds. Shut off the key and check for pressure. Use a rag because it will be around 50 PSI and will spit a good stream of fuel.

There is only one fuel pump and one relay on the normally aspirated engine. The supercharged engine has 2 fuel pumps.

If you think the battery is bad, have you tried charging it and/or getting a jump start from another car?

You could jump the fuel pump relay with the car off, just put a wire across the two switched connections for a few seconds and listen for a pump noise. Think doing it for a long duration with the car off is not good though, maybe someone here who knows better can suggest something? Pull relay, switch car on but not starting engine, jump fuel pump might be a bit safer?

That all said, a new battery never hurts, but I doubt it'd fix it unless you can get it running from a jump start as it sits now. You'd be surprised how many things a fresh battery will cure on these cars.

It was Fuel Pump , having shop install new one (Plus fuel filter) cost is $560.00 ( Parts & up to 5 hours labor for dropping rear end for the pain in the a** Lines and removing tank ) is this common or can Fuel Pump be serviced without the extra hassle of dealing with the two Fuel lines by the differential ???

The right answer is no, it cannot. Some people have had luck with only partially dropping the rear subframe to reach the lines, but you still need to get at those fuel lines somehow.

Some people have cut a hole in the parcel deck sheet metal to get at the fuel sender lid from above. I disagree with this, but it's what it is. Not on my car. Going to drop the rear subframe this weekend to do the fuel pump, along with a few other suspension parts.

I am going to get the moisture vacuumed out and add extra oil as well. I also found the right schrater Valve on Amazon it came in a kit of valves that cost me 15 bucks so I did not have to replace that hoes