1990 Jaguar XJ40 3.6, where is the fuel filter located?

fixed to the rear subframe underneath the car blue in colour i think

The fuel pump is usually located in/on the fuel tank, but with your jag, it is mounted externally from the tank. Frame mounted design with an inlet and outlet fitting...

Jack up the rear left hand side. Put the car on axle stands. Remove the left hand rear wheel.

You should be able to follow fuel line back to the fuel filter (just forward of the wheel arch) and then to the fuel pump which is behind wheel arch, (before the rear silencer/muffler).

One thing though, you might just have a faulty fuel pump relay, which on your 1990 can be found in the engine bay, left side, attached to the brake pedal hanger.

If you do decide to remove the fuel pump after all, then depressurize the fuel system first.

Remove fuel filler cap, disconnect the fuel pump relay, start engine and wait for it to stall. Turn off ignition, then disconnect battery.

Take all the usual precautions before disconnecting fuel lines, rags, container to catch spilt fuel etc.

Hope that helps, please rate me too thanks!

Try tracing the fuel line from the gas tank to the fuel injection. If you are unable to find it then most likely the filter is located in the fuel tank with the fuel pump if equiped with an electronic fuel pump. Some fuel pumps are located in the tank, by the tank, or on the engine. either way if you trace the fuel line you should find it unless it is in the gas tank like I mentioned. Good Luck!

Fuel Pump Relay

Located under passenger's dash panel on yellow connector block.

could be a loose vacuum line or cracked or worn from dry-rot look for this visually and inspect they are all plugged in or ck filter both air and fuel filter

Had a similar problem within the last year. Either your fuel pump is failing or your fuel filter is partially blocked. Change both and drive away.

The fuel pump relay on my 1990 is located on the passenger side under the dash. You have to remove the lower interior panel to expose a number of relays there will be a color guide that tells you which relay is the one for fuel.

under the car near rear end, fuel pump is inside the fuel tank

Willing to bet it is a fuel pump and or fuel filter...your symptoms were solved when I changed both on mine...

The fuel filter is under the car, and above and to the left of the rear axle  D