Hi All...

I'm out of town for work, and thought I'd leave the '85 XJ-S with my mechanic to have him do a handful of things I needed done while I was gone and couldn't drive it anyway.

One of those items was to replace the fuel pickup screen in the surge tank with the replacement part from Jaguar, because I suspected mine was backed with garbage and contributing to my intermittent stalling issues. Sure enough, based on the photo he sent me, it was. New part was ordered, installed, and reassembled.

The mechanic called me today quite frustrated, because he can't get the car to start. Apparently from what he describes he has the fuel pump working fine, and fuel pressure through the tanks/hoses in the trunk of the car, but there is no fuel in the rails. Nothing making it to the engine. He said he tried starting it on carb cleaner and the engine fired, so ignition is fine. He said he also tried to hook up a vaccum to the line in front and pull fuel through, and couldn't get anything. He was speculating either a blockage or some form of safety shut off.

Prior to the work he did in the surge tank, everything was running dandy (well except for the intermittent stalls....) and I don't know enough to help diagnose from a distance.

Any thoughts before he starts probing fuel lines one by one? If I can save him time.. I save me money. Which in turn lets me convince my wife to let me keep the car

Apologies if I've said something stupid or this is an easy question. I'm new to the game.

 

How does he know he has pressure through the lines near the tank? Did he put a gauge in-line? The only way to "tell" is to pull a hose and have high pressure fuel spray all over the place or turn the pump on and see if it squirts fuel into a container. Still, without being able to depressurize the system, he would get massive spray.

There is a fuel off switch, but I believe it works to turn off the fuel pump.

 

He must start at the gravity feed to the sump tank and check at each stage that the fuel is there: the pump, the filter behind the spare wheel (is it a new one, is it the right way round?), then disconnect the pressure feed before A bank, and blow out the line with compressed air from the filter outlet forwards. Also check that he has not somehow connected all the fuel line and breathers attached to the sumo tank incorrectly. Also it is very easy to pinch the sump tank to pump hose as it does its U turn against the boot floor. Pipe diagram herewith:

Link for him to the diagram
Fuel Sump Tank - Parts For XJS from (V)139052 to (V)179736 | Jaguar Classic Parts UK


Greg