I have been fighting the dreaded start run for couple of seconds and die on my 1997 XK8. I checked the fuel pressure today and it was 0 with the key on when the car started it went to 40 psi when it died it went to 0. is this normal? Do you think it could be the ECM? Should I send it to have it checked?
Thank You,
Jay111

 

Last suspect is the PCM (aka ECM).

 

I would state the very last suspect is the ECM.

Nearly 3 bar on idle is fine, 0 bar when the engine stalls is a safety feature and also fine.

Get her checked with WDS/SDD is the way to find out why the engine stalls, guessing will not lead to a solution.
Fritz

 

Any idea what the problem could be, it's getting frustrating.
Thanks,
Jay111

 

Is this the 97?
Where are you taking the reading of 40?
What's the FPR regulator set up on the early cars and have you checked fuel return regulation at all? The fuel pressure should remain for a while after the car shuts down, No?

Also, fuel pump? Has the car sat? Can you hear it?
Are there two pumps in the 97? Is there a way to bridge/jump the fuel pump at the relay so that it runs continuously whenever the key is on?

 

Yes it's the97, Took reading at the shraider valve on the fuel rail, car sat but all gas was drained ,lines blown out and filter replaced, it ran fine for about a week. Don't know about holding fuel pressure, it goes to 40 psi at start when the engine dies it goes to 0. Goes back to 40psi when it starts back up.
Thanks
Jay111

 

One more thing, if it sits for over a day the first start up it runs for a couple of minutes before shutting down.
Jay111

 

If I am correct you have two feeds to the fuel pump the first when the key is turned on and the other when the engine starts and it is running. See my link for MY 1999 XK8

JagRepair.com - Jaguar Repair Information Resource

I am not positive that the 1997 is wired the same but I feel confident that it is. I will provide an electrical diagram for your 1997 for you.

http://www.jagrepair.com/images/Auto.../jagxk1997.pdf

 

Thank You I will try to check it out tomorrow. Do you not think it's the ECM? I keep reading that 1997's had problems with them and leaking capacitors can cause this.
Thanks, Jay111

 

Hard to say. The capacitors leaking is often related to spark.

 

I guess for me, I am curious about an immediate drop in fuel pressure, from 40lbs to zero, immediately... That doesn't sound right. When and while it's stalling, does it sound like it's running out of gas,,, or is there just a flat stall? Are you able to view the fuel trims while it's happening? I think the trims should indicate that the ECM is trying to add fuel to mixture (pulsing FIs longer to open) by showing high positive STFT numbers on both banks....? that's IF the car is struggling to maintain pressure at the rail during regular running.

If you look on the RH rear of the fuel rail, I think it's near the schrader valve where you took your pressure readings, you should see a vac line plugged into a valve that's bolted into the rail. Is there gas smell or liquid gas in the vac tube?

 

The schrader valve on mine is on the front left fuel rail there isn't one on right rear. And it's a flat stall, not sputtering like it's running out of gas.
Thanks,
Jay111

 

What does the car think is wrong? Are you seeing any DTC codes?

 

Pulled the ECM and one of the capacitors leaked on the circuit board. I think that is the problem, going to send it to ASI for repair. I will keep everyone posted.
Thanks,
Jay111

 

That may be a problem, but I don't think it is your fueling problem.
When you turn the key to on, pos 1, the fuel pump energizes. You should see 40 lbs of pressure. if you then turn the key off, the pressure should remain for at least several minutes.
If you lose pressure immediately, it has to be leaking somewhere. Either a leaking injector, or going back into the tank via the return line, or the pump is bad and not holding pressure.
Without the ecm, you can jump the fuel pump relay for a couple of minutes, then remove the jumper and see what the pressure does.