I am a new member, but I had great luck with whomever helped me find my first issue with my 06 XK8 convertible...I can't navigate the site well enough yet to be sure I thanked those that helped. I will keep trying, but now I'm dealing with a slow to start issue.

The car is slow to successfully light off with a good, quick start. At times, it seems it will not start..but eventually does. It will lead to a worn out starter at some point, and I had the fuel filter replaced, and that's when it started...so I went and bought one at the nearest parts place, and apparently the car's filter has a clamp rather than the type of fitting that the replacement came with. So, I'm trying to avoid the dealer, and the place that replaced it drove my car for 200 miles, charged me for gas, as well as kept the car two weeks and still had it when I tracked it down. I won't go back, but I need a good Jag mechanic, and I'm just south of Atlanta on I-85 (Newnan, GA).

Long story short, the car runs well now, if I can just get it started. It has 63,000 miles, good history, and any suggestions would help. I changed the air filter, and I was told the fuel pump was putting out what it should when measured...any suggestions would be appreciated.

Thanks,

Gary

 

For the the fuel filter, check out this thread:
https://www.jaguarforums.com/forum/x...-filter-84194/

You should have the type with the quick connections rather than the screw on fitting. There are some part numbers in the thread as well.

And for the slow start, a couple of questions:
1) Does it always start slow or is it more likely to happen if the car has been driven and is hot then sits for a while?

2) Any issues once it is started that would suggest fuel starvation? Check engine lights? Error codes? Sluggish behavior? Knocking like there is lean condition?

3) If the car is running and you shut it off can you immediately restart it without having the long crank problem?

4) When you switch the key on the pump will run for a few seconds and shut off. You should be able to hear it. Cycle the key a few times to "pump up" the fuel system before trying to start the car and see if that helps.


There is a check valve in the fuel pump that is supposed to prevent the fuel from draining back to the tank when the pump isn't running but if it goes bad you get a long start symptom. If that is the case the car would otherwise run fine and only have the issue when you shut it off and let it sit for a while.

A hot engine makes it worse because the fuel in the rails warms up, expands and pushes the rest back toward the tank. Then when you go to start the car, there is no gas at the rail so take some pump running (while you crank away) to fill the space.

 

Thanks very much for that information. I have never heard the fuel pump run, but I've lost so much of my hearing from a career flying airplanes, it wouldn't be unusual for me to not hear it. I'll get the wife to listen and see it she hears it.
Also, the check valve sounds as though it could be the culprit too. If you have any information available on finding it, testing it, where it is, etc. I would like to run that down as well. I have no other issues, so it runs fine if I can just get it started. No lights, etc. but I did sense a bit of roughness yesterday after a long cranking session before it started. It left quickly, but I did sense it. I will get a good set of ears to see if we hear the pump running when the ignition is on, and I want to research the check valve. If you think it's easily checked, I will pursue that as well.
If we hear nothing, I wonder if the pump could run fine otherwise. It seems like it would either work or not work, but perhaps there's a flaw in the pre-start mechanism only if it it appears to not be audible.
Again, the check valve would sound very logical to me. If you have any info on running that down, I would appreciate that. I wonder if we have a schematic available here somewhere on the forum.
I'm amazed at the technical resources available through such helpful and experienced members. This is a great resource, and I love the car, but having the forum sure makes keeping the car going much easier. Thank you again..

Sincerely,

Gary

 

I had a similar failure, not the check valve but the integrated pressure regulator. You can see the pump assembly here, which should give you an idea how it all works.

https://www.jaguarforums.com/forum/x...nalysis-80018/

Unfortunately, the check valve is part of the pump assembly, so can't be replaced or repaired easily. It's all a bunch of custom molded plastic parts and not a standard piece in the whole mess.

And you can't just put a check valve outside the tank either, because it's a returnless fuel system and when you shut down a hot engine the pressure will build up to be so high that the injectors can't open. You'd have to add a check valve and a pressure bypass for everything to work properly.

 

Not that Charlie needs any agreement from me, he knows what he is talking about. I will say however that I have good hearing, and I never have been able to hear my fuel pump, not ever. I know people on the forum have said they can, and I don't know if if it is the 2003+ MY pumps or the older model pumps, or all. I can't explain why I can't hear mine, maybe it is a certain tone I am deaf to, like my wife's voice. I have heard the pump in other cars, just never in my XK8. Lastly, and this is only my opinion, but if I had to do it all over again, I would do as I did initially, which is have the dealership replace the pump rather than myself or an independent. My reason is because of my admittedly unusual situation that 5 fuel pumps went bad all within a year from the initial replacement, all were bad check valves, and I believe indies or parts guys would have told me to get lost with so many of them going bad. I know of a couple of others on the forum that have had a new pump go bad after installation. Some suggest the sticking check valve is ethanol related and I wouldn't doubt it. I live in humid Florida, and ethanol absorbs moisture, and I don't use my car as a daily driver so fuel can tend to stay in my tank longer than typical, making ethanol issues more problematic. As a precaution, since my last pump was installed I use Briggs and Statton fuel additive at every fill-up: it is specifically designed to combat the effects of ethanol.

 

Other things to check: with an OBD tool that does live data, look at sensors like ECT & IAT to see if plausible. Used by PCM to decide fuelling so if sensor wrong PCM gets fuel wrong.

Tools like elm327 are a few bucks.

 

I am having some difficulty with the wording of your post. I think you said the long-start issue was not there before you changed fuel filters and it was ok and starting fine before then and promplty began when you changed it?

If that is the case the fuel filter is almost certainly the problem. It would be uncommon to have something else fail at the same time.

If that is the case I would replace it with an OEM jaguar filter. It could be this drainback valve in the filter people are talking about. Typically I think OEM filters and such are just overpriced however in this case maybe not.

There are several reputable dealers in the atlanta area and I would take it to one of them if you can't do it or troubleshoot it yourself.

I would not pay the guy who put 200 miles on your car. Sounds like he just used your car as a free rental for a week. I would call my credit card company and do a charge off.

 

One other thing - does your model have 2 fuel pumps? If it has only one it is working if the car eventually starts. If it has two make sure they are both plugged in and powered up.

One shade tree mechanic technique to depressurize a fuel system is to unplug the fuel pump relay or power lead and run the car until it stalls. I think this is uneccessary in a Jag but if they did it and did not connect one of them back up it could be hard to start.

 

Had this problem with my 2000 XK8. I thought it was the check valve as talked about in another thread. It turns out the hose that is inside the fuel tank had deteriorated and had melted itself inside the fuel pump. When I bought the car two years ago the previous owner had changed out the fuel pump at the Jag dealer (+$1400!) but they had neglected to change this $20 part.

 

See post #6 unde this thread.

https://www.jaguarforums.com/forum/x...0/#post1061110