Hi guys,

Bought a 99' XJR on Nov 5th, and after a fantastic day driving some of the best roads Hampshire has to offer she's broken down....I've been reading as many of the fuel pump/relay related problems I can find on the net and this website but none seem to be an accurate fit for what I'm seeing so hoping one of you fine people may have an answer!

Problems started after I took some friends out for a 'spirited' test drive in chandlers ford, just around the block, over a few speed bumps but positive I didn't hit them hard enough to cause problems, returned to the house to let them out, switched off and went inside.

Jumped back in the car within 5 minutes and she turned over fine, pulled away and revs wouldn't build, got about 300 yards and car just died, that night no matter what I tried it would crank but not catch at all, in the morning got the RAC out to have a look, and while he was blindly pulling fuses and relays without any idea of where anything was he determined that there were no error codes but the car would now crank, catch, fire for a few seconds then die once the primed fuel had run out.

He eventually got the car running by connecting a piece of wire with spade connectors from one of the fuses in the boot to fuel pump relay 2 terminal which allowed the pump to run...which would have been great and allow me to get the car home for further diagnosis... unfortunately he decided to be smart and throw an amp meter into the circuit to see what the pump was drawing, after which the temporary fix stopped working, he blew the fuse in his amp meter and my car is now still stuck in chandlers ford!

So now you've got through my sunday morning ramblings, my questions (in no particular order) are... We got the car running so it can't be the fuel pump surely? The relays look incredibly simple and little to go wrong with them so would they fail? Why can i not find any reference material for which fuse is which in the trunk? (the RAC guy had no accurate data on fuses/relays for my car)... and the big one, Does anyone know what I can do to fix my new toy!!!!

Many thanks for any help, it'll be greatly appreciated!

Dean.

 

Forgot to mention that after RAC Man's meter fuse blew the pumps on my car refused to 'prime' at all, does anyone know if there is a control module in the circuit that may have gone? as none of the fuses in the boot box have failed...

 

Fuel pumps, and the associated in tank wiring harness can fail as you describe. Easy to swap the pump relay with most any other in the panel to eliminate that question without a jumper wire. The relay feeds a fuse, did you check that?

 

Hi test point,

Thanks for coming back to me, do you know which fuse relates to the fuel relay?

 

On my 2002 XK8 it is #7 (20 amp) in the trunk fuse box. Don't have you specific model's chart handy but there is a good chance it is the same.

 

Check out the attached PDF, it may shed some light on the relays and fuse boxes. There are two fuel pumps on the 99 XJR which is why you have the two relays.

 

I attached the 1999XJ trunk relay and fuse layout.

HTH!

David

P.S.
The brown relays are the "simple" ones.
To test them just interchange them with any other brown relays with a matching number you'll find in the car.
(I think there are at least 10 of them in the XJ.)

 

A 2nd thought...

As the fuel pumps are switched on and off by relays controlled by the ECM is it possible, that the fuel cut-off switch somehow got engaged?

That would explain the failure of both fuel pumps at a time...

It is located on the right hand side footwell.

Good luck!


David

 

Hey guys, appreciate the info and posted diagrams, unfortunately as a new member here I cannot view the attachments...

fuel cut off eh? that may explain why when the RAC monkey messed around with ampmeter and upset the ecu there is now no priming at all of the pumps?

Worth a try anyway, I've got a ex-jag tech coming out in an hour or so whos a friend of a friend so hopefully he'll be able to take your suggestions and narrow it down! will post the solution when I get it!

 

PM me your eMail within the next 15 minutes and I'll send you all the diagrams!
(I have to head out in 15 minutes...)

 

Hi David,

Thank you for the offer, I had gone out by the time i saw your message.

Had the Jag Tech out today and he's diagnosed replacement of both fuel pumps....uh oh...

So.... 360GBP later parts are on their way and he's going to take the tank out...

Hoping its just the connecting wires in the tank that have fried and I can send the pumps back to the main dealer, unfortunately I have a feeling that I'm not that lucky!!

On the plus side i had a chat with Paramount Performance tuners who specialise in 'r' jaguars so that once she's running sweetly again I can start the stealth upgrade process... starting with air, exhuast and ecu remap...perhaps throwing in a new smalled supercharger pulley to help spice things up a bit....

 

I have the Paramount conversion, go for the bigger lower pulley. The re-map isn't required, the induction I could do a better job, the exhaust I'd recommend Blueflame, just my thoughts, my car had the "upgrades" before I bought it, so didn't get relieved of the near £3k they charge....Gerry's OK though.