hi lads and lasses
could you please help me. my 1994 xj6 3.2 will not start. when i turn on the ignition, the fuel pump make the usual noise from the rear of the car as it get itself ready to prime up. but it is now not stopping and still making the whirring noise, thus the car will not start until this stops. i dont know if this is a relay problem or could the fuel pump be on its way out. has anybody experienced this problem before and could you give me any answers. many thanks.

 

It is probably not the relay. Relays are on/off switches that use low current (computer signal) to switch on a high current line. If you hear the fuel pump running at all then your relay is working.

Fuel pumps are always running in most car applications. The loud noise at start up is the fuel pump spinning with little resistance probably pumping as fast as it can be supplied. Think of a weed eater. If it is full throttle and cutting no weeds the engine goes very fast and gets very loud. Add just a little bit of resistance (weeds) and it slows the engine down a little but lessens the sound quite a bit as well. My old out of tank Airtex was noisy as can be most of the time.

My guess is your fuel pump is worn out or you have a major pressure regulator failure. As you say the pump runs, you can hear it. Even if it only runs for a second it should build enough pressure to make the car at least start.

My two cents...

 

I had a pump failure so I know a little about the process. A Jag pump will only prime for a few seconds on start up. If it continues to run, it would mean that there is a leak somewhere so it does not reach the correct pressure to shut off. A silly question, is there fuel in the tank? If not it may be running due to no fuel to build pressure. But as I mentioned the pump only stays on for 1-2 seconds per Haynes and other searches I found.
I dont know if this helps or confuses the matter

 

hi jaggier.
yes there is fuel in the tank although it is low but still above the red. thanks for your comments, much appreciated

 

Ah, ok. I am still cloudy on how these fuel pumps work. I know my out of tank always runs but goes silent after the first couple seconds. The pressure regulator allows for some return which the pump needs to replace almost constantly. Haynes says in the fuel press. check section that a blockage in the fuel return line could cause excessive pressures....

Anyways heres your test, get a clamp and pinch the fuel return line shut just after the fuel rail. Does the whirring stop/car start? Yes? Bad pressure regulator. No? bad fuel pump. (As per Haynes)

 

After you post in here a few times, you can use the search feature within the XJ40 section. Fuel pumps and CPS's have been discussed maybe 5 to 6000 times.