Please please please lol....I hav e tried searching for this but to no avail....if there is a relevant thread please point me to it!


I have recently bought my XKR and it seems to suffer from just about every known fault going.


ABS module
Drivers seat electrics
rear view mirror
Squeaky belts when cold
etc etc


All of the above I can deal with but....


The engine starts and idles fine and most of the time runs very well.


Intermittently it will lose power when accelerating hard....there is no stutter or apparent misfire its just like its losing cylinders under load.


All of my paperwork suggests that the car has had this problem on and off for years.....one lot blamed on water getting to the spark plugs.
The latest pointing to a fuel pressure problem that was " fixed" by changing the fuel filter.


The compression has been tested twice although I have no results.


I may add that this is always when in drive....when using the manual shift it seems to pull like a train up to the limiter in second and third with no problems.


I am suspecting a fuel pump issue? Or have read that early models suffered from a throttle body problem.


Any ideas or links to previous threads would be appreciated.


Al.

 

XKRs have 2 Fuel Pumps. The one that comes on under high loads may have failed.

 

Hi and thanks


I assume that they are both at the tank end and that the tank has to come out????

 

If you have a coupe you can access the pumps through the speaker opening. Use the search to find a thread detailing the process.

 

I have the later single pump type, but IIRC you can test it by pulling fuses.

When the primary fails, I beleive the car will run on the secondary so if you pull the fuse of the primary, then you will know pretty quickly if the secondary is dead. Better to confirm the problem before taking the pump out.

 

 

My XKR primary fuel pump has been out a year already. It still runs excellent even at triple digit speed, I'm not messing with it right now. It is almost a non issue. But you do have to unhook the hoses under the car to be able to tilt the tank back to get inside. There's a metal guard of some type over the tank. One guy on here describes how he used a BIG hole saw on the cover so he didn't have to deal with the hoses. I liked that idea. The quick connectors see a lot of dirt where they at, so I am not thrilled about unhooking that on top of the differential.
It sounds like the coils are getting wet, then drying out like mine did a couple years ago. Before I had time to fix it, I duct taped the louvers in the hood shut on the underside. This bought me a little time. But the tape melts with engine heat, so this was very temporary to make a run to the store in the rain. When I got around to it, I removed the coil covers and found some of the brass inserts had pulled loose from the valve covers themselves. I super glued them back in flush with the valve covers again. I removed all the coils and cleaned the wells with compressed air, solvent and a rag. I used petroleum jelly on the boots liberally, and the coil cover gaskets. Did this 2 years ago and yesterday I drove 150 miles in the rain stopping several times with no probs at all. The coil covers need to have a decent seal to keep water out the spark plug wells. I remember one time I drove it almost 50 miles before they dried out. Didn't like to do that, but sometimes you don't have much of a choice. Just a high humidity in those wells will make a terrible misfire. Probably 60 to 80,000 volts in there. Super glue and Vaseline, haha. Jag probably hit ya for a grand to fix that.
You can swap that seat module with the one on the passengers side, then look up how to fix broken tracks in circuit boards. Hope you got steady hands. It takes a 10mm socket to get the module out from under the seat front. You'll see how the cable plugs come off.
Bad compression from rings and valves will not be an intermittent problem, so I wouldn't suspect that.

 

Thanks everyone....that gives me something to play with when I get back home from holidays.....cheers for the info!


I don't think its the coils getting wet as the problem seems to arise once the engine warms up....it is either a pump issue or coils breaking down once the engine gets hot at a guess???


The diagram above is very helpful! Once I'm back home in the UK that is the first thing I'll have a play with.


The abs module is coming out first to get repaired so while that is being done I can play with the seats to get them working.......it seems to be a wiring problem because it blows a fuse every time I sit on the seat! lol Some proper rewiring should take care of that I reckon.


Then its onto the steering rake / height adjustment as that's intermittent as well.......then the squeaky belts etc etc etc......she will be a nice car again eventually!!!!!

 

I'm assuming that this is for the convertible but the relay positions will be the same for my 98 coupe?

 

Yes, but the top related relays will be missing.

 

I got a little confused in this thread. Someone please confirm that my '03 XKR Coupe has only fuel pump.

I'd have to agree that Al's power problem is likely to be fuel related. However, he did say it pulls all the way to red line in 2nd and 3rd gears. If the throttle is wide open when he does this, then the engine should be getting full fuel supply to meet demands. Just something else to ponder I guess.

 

4.0l cars have two pumps and a return style fuel system whereas the 4.2l cars have a single fuel pump and a returnless style system.

 

Yes it is a bit strange that it performs better in manual......but I guess it may feel that way because the kick down gets lazy in auto so it is more apparent?
And it is an intermittent problem at the moment....

 

Of course when in J2 and it kicks down to first the car friggin FLIES! I only get about a second before I hit the limiter.

If it was fuel starvation wouldn't the lean mixture codes pop up?

 

When I had it checked for the abs lights there were no other codes....will try the relay trick next week and see what happens

 

If any upper cam chain tensioners throws a shoe, it would make that exhaust cam jump a tooth and retard that cam. It might then give a code for excessive temps for the catalytic converters due to uncontrolled fuel air mixtures. It would pull like crazy to the redline, but have a rough cammy idle. The main clue to this happening for me is the smell of the exhaust at idle. It won't be a normal smell. You can't miss it. Pretty nasty to me anyway. This is easy to check. Remove valve covers, bump the starter till all 4 flats on the cams line up perfectly. If they don't, you've nailed it.

 

no, at least for me, when I had a fuel pump issue causing low fuel pressure only when flooring it, I never got any codes, no lean, no misfire, no low fuel,pressure, nothing. I determined I had a fuel pressure issue by watching fuel pressure on my OBD reader while,stepping on the gas pedal. At light to medium throttle, normal fuel pressure readings, but with heavy throttle, fuel,pressure would drop to 10 or so psi.

 

Thanks...what was the cause of your problem?

 

My issue was a bad fuel pump, or broken tab holding the check valve onto the fuel pump (check valve and fuel pump is all one assembly). Rev Sam has a post about the check valve broken tab. It allowed fuel pumped out by the pump to squirt out back into the tank rather than into the fuel line, thus, reducing pressure under load.

Remember though, the 2003+ is a returnless fuel system, different than the earlier models, and I don't know if the earlier model has a check valve. I know the fuel pumps are completely different.

Honestly, the intent of my initial reply was only to suggest or show that fuel pressure can be normal at idle and light throttle, and low under heavy load.

 

Final got round to this as the car was behaving itself....but now I have a full on misfire at full throttle acceleration.
Its not a uniform misfire though.
I pulled the primary pump relay and it made no difference at all so I'm wondering whether to just change the pump just in case and go from there?