Hello, This is the first time I have ever attempted to work on a Jaguar, and I am trying to diagnose a fuel pump issue with my 05 S-Type 3.0.

The car is intermittently running out of fuel. This problem just started yesterday. The car will run fine for 10 to 15 minutes. Then when it gets to an idle, it starts sputtering and running out of fuel. It will start and run for a few seconds, but it takes a few minutes for the pump to start working and get the engine running again.

I have the seat out, and a volt meter checking pump voltage. The wiring diagram I found is showing the yellow wire into the pump supplies variable voltage from the rear control module. I've been checking voltage on this wire while the car is idling, and the voltage drops right before the engine starts sputtering, then it goes back up, then the engine dies.

Could the fuel pump be going bad? Or is there a problem somewhere else causing the fuel pump to shut off and back on?

Any suggestions would be much appreciated.

Thanks.

 

Often a jag stalls due to an air leak, whereas the fuel pumps hardly ever go bad. So, are you SURE it's not an air leak?

A blocked fuel filter would be a suspect.

The fuel pump is PWM so you can't just measure voltage. Do you have a 'scope?

 

I replaced the fuel filter today, and drove it. It didn't fix the problem.

I don't have a scope.

I knew the pump was PWM, and the voltage will vary. I was wondering how to determine if the rear ECM may be failing?

 

Air leak, as in the intake/air box? I've checked that out, and don't see anything.

I'm also getting a P0627 code, which is fuel pump A control circuit.

 

More likely damp/wet in the trunk, either now or in the past. You don't need much damp or corrosion to have problems.

Even a tiny air leak in any of the many (and there are many!) things that should be vacuum tight will give you grief.

Stalling at idle is normally an air leak. A failing fuel pump usually causes a lack of acceleration, i.e. trouble when high flow needed - you don't have that. You could have a poor signal in the PWM drive from the PCM or the other going to the pump, but an air leak is easily #1 suspect.