My 1996 XJR recently started misbehaving under hard acceleration. At About 3500 RPM there would be a sudden loss of power. this also occurred if I cruised up to that RPM. From searching this forum I narrowed my problem down to possible secondary fuel pump issue. The issue was cured by swapping the relays with my spare XJR. when i had the fault the car started as normal, which threw me a bit as I understood the secondary pump also assisted starting.

My question is: which of the two turquoise relays is for the secondary fuel pump? and what is the interaction between the two fuel pump?

Thanks to all who share there knowledge on this forum without which my XJR would have been consigned to the scrap yard long ago.
Regards
AVRO RJ

 

I don't have the answer to your question, although it does sound interesting for any XJR6 owner like myself. So I'm curious to see the replies. However I don't think you'll get the exposure in the X350/X358 forum for your X300 XJR that you'll need.

The moderators should move your post to the X300 sub-forum soon, then the X300 folks can chime in and hopefully answer your question.

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Thanks for pointing that out. Not a regular poster on the forum.

 

Hi Avro,
did you figure out which relay to replace? I am having a nearly identical problem on my 1995 XJ6, and have been going crazy trying to figure out a solution. Engine fires and idles beautifully, and runs like a champ up to about 3500 to 4000 RPM. Then sputters and balks, and I cannot get anymore revs out of engine even with gas pedal floored.

MAL
1995 X300
88,000 miles

 

Hi
I swiped the two turquoise relay that are in the boot fuse box tray and that cured the problem. However several days later and the problem is back. I suspect bad or corroded connection. I still would like to know which relay is for which pump, so far no one has volunteered that info. I can hear the primary pump when the ignition is switched on so that seem s to be OK. If I can identify which relay powers the secondary I may try to wiring it to see if I can hear that pump running also. Just need to find the time.
Avro