Hi all

Looking for some assistance with an 06 XK X150, 4.2 NA. A few weeks back my car would start, idle for 10 to 15 seconds and cut out, throwing code P0087, Fuel Rail Pressure Low. We tested the circuitry, all relays etc appear to be working as you'd expect, live feed into the fuel pump, feed coming out, but motor not engaging. As such, changed the fuel pump (fun job!), only to find on first attempted start up, the fuel pump failed to prime (we did test the pump functioned before installing it and it did so with no concerns).

This then lead us to the Fuel Pump Driver Module, another beast of a job as my XK is the 127th production line model, meaning my FPDM is located on the carbon cannister and not in the boot like most are. This made it far more difficult than it should have been but eventually, job complete. The pump primed, car fired instantly and ran perfectly... for four days, then the exact same issue re-occurred, idle for 10-15 seconds, and die, any attempt at throttling the engine would cause it to run as lumpy as hell and also die.

We decided to change the fuel pressure sensor but it's not affected the symptoms at all. We've also inspected the EGR just to be cautious and again, it's in great condition and appears to be running as you would expect.

I guess my question is, has anyone experienced similar as we're struggling to figure out our next move. I've thrown plenty of cash at this recently and received very little return so I'm loathe to keep doing so with the same results.

For what it's worth, when this problem first began, I changed the battery and the same thing happened, it ran perfectly for three days only for the same symptoms to return. I can't quite understand why I get perfect performance for just a few short days and then the faults come back as if they never left.

Sorry for the essay, any assistance would be greatly received.

Kev

 

...you mean you changed the battery for a brand new one? And you've been monitoring battery charge state and/or using a maintainer?

 

Hi, thanks for the reply

Yeah, that's correct, battery replaced for a brand new unit, charge state maintained as you would expect. It's an absolute enigma that's driving me crazy.

 

sorry. empirical evidence is best. With the battery sitting cold for 6 hours, without a charger or maintainer attached, and with the car not running in this period, what is the voltage of your battery?

Also, what are all the codes that are thrown?

Cheers.

 

Hiya

No worries, appreciate any help on this. At last check a few days back it was at a resting voltage of around 12.5v. The only recurring code has been P0087 but I did receive P0627, Fuel Pump A Control Circuit Open last Sunday - it hasn't returned at any point since then.

Cheers,

Kev

 

A bad fuel injector could cause issues as well... do you smell gas ?

 

Thanks for the reply pal.

Yeah, I have noticed a smell of gas. I've had a fun week with vehicles, borrowed a company fleet van and had the gearbox fail on me after 50 miles, waited 7 hours for recovery but when they did come, I took the opportunity to ask the advice of the mechanic, he also advised to check the injectors.

I think it's going to be a case of stripping them out and having them tested. Turning into a hell of a job this!

Kev

 

Since you have a non-/R, injectors are easy-peasey. The blower easily adds several hours of extra work to even SEE the injectors.

 

Cheers buddy, hoping to find some free time over the coming days to tackle it but work continues to get in the way.

I'll report back with the findings once they've been tested

Kev

 

Rock auto has injectors for $80
https://www.rockauto.com/en/moreinfo.php?pk=10706588
Don't overpay for testing/cleaning etc...

 

Thanks for the link pal, much appreciated. Hoping to have this job completed in the next few weeks but there always seems to be something getting in the way lately.

Kev

 

Low fuel pressure! Change fuel filter, or change fuel pressure regulator. Under 55psi and the injectors don't work well or not at all.

 

"My fuel rail was holding 35 psi when running , but as soon as I shut it off it would dump to 0psi.
Installed a check valve in the fuel lin, incase the fuel pump was having issues. But that didn't help.
Decided to change the fuelpressureregulator cause that was the only thing left. Could not believe the fuel injectors would loose pressure that fast.
Pulled the regulator and this is what I found."
His was a Delphi FP10385 that needed changing