Hi folks , well finally the sun has come out and i need to get the XKR running , I will keep it brief , used the car for a fairly short run and it was running fine , stopped at my sons for half an hour and when restarting the car it cough and spluttered and wouldn't run , finally after a few attempts it won't fire at all , seemed classic fuel starvation symptoms to me , towed it back home !
having now checked through i find that both fuel pump fuses and relays are ok , the earths on the multiple connector into the tank are ok (0.00 ohms) , however there is only 10.75v to the black /white connection which drops to 9.6v on cranking .
there is no power to the red /white wire connection on cranking.
we put direct 12v to both connections to the fuel pumps seperately and neither pump is running .
it would seem that these cars suffer from pump problems and that both of mine are not running anyway but shouldn't i be getting more than 10.75 v feed anyway
Any ideas or advise would be very gratefully received , Thank you

 

The engine ECU ( which controls the fuel pump relays ) will fail somewhere around 11.5 volts . So the first priority would be a fully charged battery of 12.75 volts . You can remove the alternator and the auto parts store will spin it up for free on a machine to test it . It should read around 13.5 output on the B + post of the alternator . If the alternator is bad you can at least run the engine on the battery only until it drops below the 11.5

When you turn the key to the on position before start you should get 2 clicks on the # 1 fuel pump relay , on 5 seconds then off . The relay won't click on agian until the ECU sees engine rotation , safety / crash design .

The # 2 relay doesn't come on until 4000 RPM through the ECU , someone mentioned that it will turn on after a while of unsuccessful starting sequence .

 

I'm not familiar with the XKR, and not sure what year we're talking about, but have you checked whether there's any pressure at the Schrader Valve (like a tyre valve) on the fuel rail on the left hand side of the engine.
A quick and easy way of ascertaining whether or not the fuel pump(s) (depending on year) is/are working.

 

It would be most helpful to know what Jaguar model and year you are having trouble with. You can use the User CP button at the top of the forum and add that information to you signature. Since you mention 2 fuel pumps I have to assume XKR.
First for troubleshooting is to make sure the battery is fully charged. Then turn the ignition key to the full on position and wait for 5 to 10 seconds and then turn it off.
On the end of the fuel rail you will see a cap that looks like a tire valve. Remove the cap and with a rag and screwdriver press down does it squirt out fuel? If it does the pump is charging the rack correctly.
The next step would be to remove the crankshaft position sensor. Clean the face thoroughly, check it for continuity and reinstall. Then attempt to start again.
The ECM will not give a signal to start the fuel pump unless voltage is sufficient and the CPS has provided a signal that the engine is rotating.
If you suspect a weak fuel pump relay you can swap the relay for pump 2 to the pump 1 position.

 

Thanks for the advise , have replaced both fuel pumps and the XKR is up and running , I've got the engine management light staying on now but will give the car a run tomorrow to see if it clears , there's always something.