Fuel Pump Pulse at Crank '02 XJ8

On and I’m sure I knew this at one time, but does anyone know if the fuel pump runs at power on before crank? I know it needs CKPS pulses in order to continue to run, but I don’t remember the startup sequence.
My wife’s XJ8 will crank but not start and there is no fuel pressure at crank. My hands are too fat and arthritic to easily get to the fuel pump leads to do a proper diagnosis!

Put a 30/87 jumper in the relay box for power ALL THE TIME.

Thanks, bob! I assume its the relay box in the boot?

Found it, thanks for the reminder!

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My XJR does.

Fuel pump failure is common on these. (it’s in the tank)

DONT KEEP CRANKING IT…Just incase, you didnt do the tensioners.
If you did the tensioners its the pump.
Once again, how many miles on the car, 100,000 is the limit, if you did not do the tensioners, if you keep cranking, the valves start banging!

Hi Ross, good to see a post from you it’s been a while since we discussed fuel pumps on the X308 and ethanol. Hope it’s not the pump as that’s a PITA to change. Seem to remember there was an ECU fix to stop the fuel pump at start up to prevent washdown and loss of compression if the engine hadn’t got to temperature. Another PITA putting oil into 8 cylinders to get it started if you didn’t want to risk destroying the airbox by prolonged cranking and a blow back.

It’s a mini X300 reunion.

Thanks for the good advice!! But yes, I have changed both primary and secondary tensioner, although the ‘02 came with metal upper tensioners sand a Morse style silent chain for the lower Chain which has few of the issues with the lighter weight roller chain use previously!

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Jump on the pump then
Good luck

No Jack or Maximus as yet!


The infamous Gang of 5, reduced to 3.

Not forgetting Jagsongas (Steve Sparrow), Jim Butterworth, Atty Dallas, Iggy and Gus to name but a few sad that the fun side and badinage along with new and deep technical issues are no longer posted.

I keep in touch because with demise of my beloved X300 I was forced to buy an S Type as I couldn’t find a decent X300/308 so I’m in whole new territory technically, even the switching logic for lights and accessories is reversed and I suspect I will need more help as time goes on.
Still wishing all J-L members a Happy and above all HEALTHY New Year in 2021!


All the best!!!

What about Darrell Grimes?

Re my last post. I don’t know why, but Darrells name popped into my head today. I’ve just done a quick Google, and it appears Darrell passed away in June 2016.

Farewell old friend, may you rest in peace.

I now remember why last time I replaced an X-308 pump I swore I would pay someone else to do it the next time!

Getting the fuel line separated from the tank under the car is incredibly difficult. I lowered one side of the rear suspension module, and even with the car on a lift it is a large PITA to get the “quick connect” line loos. Several try’s later, I remembered that last time I made a push tool by splitting a plastic pipe lengthwise to push on the plastic extraction tool. The metal tool I have would not work for some reason.

Lines loose, now I have to wrestle the tank from the boot. Wish me luck!

Good luck and happy new year
Never run those pumps low then they heat up and burn out

Sorry to hear that Darrell is no longer with us, his name had slipped my mind.
Hope the tank removal goes well Ross and as GTJoey says don’t run the tank low when you get it going again.

I recognize that I am treading on sacred Jag-Lovers ground here, but does anyone have ANY evidence that running your tank low causes or even contributes to fuel pump failure? I have replaced a number them, so there is definitely correlation between failure and running the tank to just short of empty because that is the way I drive, but I don’t believe it is causation! all of the pump failures save one were on cars with 150,000 + miles. And that one was actually the fuel line blown off the top of the pump from the factory fitment!
I have now cut two failed pumps apart and see no sign of any heat issue. No discoloration, no binding, no distortion of plastic parts. NONE! I have found in both cases that one commutator brush was worn out, while the other still had 6 mm or so of life left.
I admit I have a small sample to make any conclusion, so that’s why I ask for evidence of some other failure mode.
I realize refilling the tank early, changing the oil every 3000 miles, pouring in Seafoam or 2 stroke oil makes some feel better about themselves, so, as we say in the Southern US, “have at it”. But without evidence, I don;'t feel the guilt! :slight_smile:
Happy New Year everybody!