Hi Guys took my xj8 out yesterday ,and she has developed a missfire .all was going fine with my usually feather light touch on the throttle (i never hammer it unless i want an ocassional bit of excitment ) due to petrol cost ,and respect for the old girl.
Anyway i decided to push it a bit and she died .Shes fine on gentle acceleration ,but as soon as i put the pedal to the floor it seems to be gulping air but nothing else .No missfires on tick over sweet as a nut. no overheating.
Same symptoms when out of gear on return home . pressing pedal hard to the floor out of gear she sounds like shesbeing starved of fuel
Any ideas guys ?
Cheers

 

first test is fuel pressure at the injector rail, there's a shrader valve that you connect a pressure tester to under the bonnet on top of the engine, it should be 40psi +- a couple. If it isn't in that area, time to check the fuel filter then pump, chasing the starvation back. There is a rev limiter in neutral to 3000rpm, you might be bouncing it up against that also.

 

muso58, Did you figure out the issue with your car?

 

muso: I could be reading more into this than stated and quite possibly out in left field. However, it's my understanding that pedal at the floor is actually a no fuel position, based on threads regarding getting the car to fire following possible cylinder wash. Could it be you're getting to the floor (no fuel position) too fast for the car to pick speed? Try accelrating nearly to the floor, or slowing it up a bit and see if she picks up speed. Having never tromped on mine, I couldn't tell you if this is what's happening or not. I'm sure if I'm off base one of the techs will chime in and correct my presumptions. Good luck. Sean B is on track, but you can't go wrong with a new fuel filter, cheap attack.

 

i guys . i have not yet had a chance to check fuel pressure ,as i dont have a tester . i need to do this first i think before i go any further .
just one other point if i take revs up slowly it will go to full revs (while in neutral standing still ) .so would maybe discount fuel starvation ?.also if i hit a hill it struggles to climb it.
i will keep you informed cheers steve

 

Fuel used depends on engine load. So, you have not proved or disproved that possibility.

 

It sounds like fuel starvation...replace your fuel filter and see what happens.

 

I'd be interested to know if the fuel filter does the trick too. If you disconnect the fuel filter, is there a clear way of checking it? I can blow through mine, but not sure if that really means anything.

 

Hi guys i ordered a filter yesterday so i will let you know what happens .
incidentally what are they like to get off ?havent taken a look at location etc yet

 

That will be the rev limiter, set to 3000 rpm when not in gear.

If you have the possibility to get the codes read, that might be helpful in the diagnosis.

 

nuso:
You ask what fuel filters replacement is like?.... Its a PITA on these cars. Be careful to use a backup wrench when loosening or tightening the lines. Removal of the left rear wheel helps somewhat. My mounting bracket was also corroded on myXJR causing even more grief.

 

Very easy. Go under the car in the driverside rear wheel well location. You need a 5/8" wrench (16mm will help too). But thats it. One line on one side, one on the other. It'll take a few minutes only because the location doesn't allow for big turns of the wrench. I'm thinking about doing mine today as well.

 

Well, Swick. You either have smaller hands or better skills with a wrench than me. But either way, muso will have trouble finding his fuel filter in the "driverside rear wheel well location". Check his location.

 

Well my hands are pretty well proportioned to my body, 6' 230 lbs. If you scoot under the car head in from the rear bumper you have plenty of room. I guess what I should have said was "rear wheel well area" rather than "location." If he looks around that area (not in that location) he'll see it. I just did mine this morning, literally took about 5 minutes. a 5/8" wrench for the lines, and a small adjustable for the filter. $10 for the part. I didn't bother removing the wheel, just jacked the car up enough to get it on some supports and get under it. Hope that helps.

 

Sometimes, the lines are very hard to budge - if the cars in the UK are anything to go by, be prepared to give them a 'stiff arm' to crack them. Let the fuel system purge before going for a start-up after fitting the filter - let the pump run for 10-20 seconds. I'd go for a before and after pressure test to to confirm anything.

 

Swick:
In the UK, "drivers side" is the right hand side! That is the location I was talking about.

 

ah, that one went right over my head man.... I thought you were referring to my verbage. hahaha.

 

Hi guys ,
Fitted filter today ,(wasnt too bad to do ) . and i knew as soon as i had loosened i pipe off that i had found it .a thick rusty liquid poured out of filter .wHEN I REMOVED FILTER THE INNARDS WERE RATTLING ROUND INSIDE AND IT WAS TOTALLY BLOCKED .i rebuilt the top end a few months ago after it had been off the road for 3 yrs new head gaskets skimmed heads etc .THE TANK HAD BEEN FILLING UP WITH WATER WHILE IT STOOD AS A RESULT OF BLOCKED FILLER CAP DRAINS. so after cleaning tank and replacing knackered fuel pump i got her running again .this has obciously been another symptom .Thanks for all your help .happy days are here again
sorry abouit caps been a long day and i cant type at best of times .

 

Great job muso! Glad all here could be of some help. Let's hope none of that rusty muck made it past the filter to the injectors. You should know right away if it did. Enjoy the ride.