I have spent several weeks looking through this forum and have found it to be the friendliest and most helpful forum I have ever seen. That alone confirms I made the right choice when I bought my xjr about a month ago, as if that lightning strike when I stomp the pedal isn't confirmation enough. I have one issue I have yet to resolve, however, and I was hoping for some suggestions.

I have a strong but intermitant fuel smell in the cabin, most pronounced on warm sunny afternoons. I have already changed some leaky coolant hoses, heater valve, and the upper air intake/throttle body seal. I was hopeful that the tb seal would cure the problem, but no luck. Once that was ruled out, I began to make mental notes of when it occurred. It seems to be related more to changes in the weather than anything else. This weekend has been fairly cool for S. Texas, and no strong odor, but the last warm sunny day it was very strong. I cannot find any leaks, fuel pressure seems fine, car shows no noticeable performance or other probs, other than some minimal white exhaust smoke on the first start of the day, which I assume is some leftover coolant from the leaky hoses. Given that the problem seems tied to the weather, I am now thinking fuel vapor may be escaping from the fuel tank or filler neck, which gets more pronounced as the fuel heats up during the day, but I cannot isolate it to any particular location. I notice that the fuel filler always has a little gas above the metal gate. Is this normal? Any suggestions for where this smell could be coming from if not from the filler neck? Maybe as simple as a new gas cap?

Thanks for any help you guys can give.

 

There was a recall on the gas cap several years ago - I don't recall (!) what prompted the recall - but a new gas cap appeared in my mailbox one day.
The other thing to check is the vapor canister, and the purge control valve.
________

1999 XJR

 

Thanks Markus. I will check on each of those suggestions and hopefully the problem will be easily resolved.

 

Heavy gas odor returned this afternoon, accompanied by a CEL and momentary restricted performance. Codes came up as P1797, P0171, & P0174. Upon further inspection, I discovered a corner of the upper air intake assembly cracked and about 1" X 1" missing, right where the metal clip should engage. Air filter rubber seal was black, making it much less noticeable without close inspection.

Any ideas where to locate a suitable replacement, or does anyone recommend switching to K&N cold air intake with cone filter?

Thanks again for any help.

 

Greetings,

Are you talking about the air cleaner top cover, or the lower housing?

An air leak there is not likely to throw a code in my mind, it's forward of the Mass Air Flow Sensor. I think those codes might be from the MAFS sucking unfiltered air, and cleaning it should be sufficient. Not so sure you are getting fuel odor in the cabin from this, however.

 

The air cleaner top cover, yes.

I suspect that there may be several problems that need be addressed, including cleaning or replacing the MAFS. When I first started to smell the gas in the cabin, I suspected the MAFS, but then we found the bad air intake/throttle body seal and replaced that in hopes of curing both the gas leak and a small oil leak. Oil leak was resolved, but still have the gas smell. Given that the occurrences were tied to the weather, I moved away from the MAFS idea on to other possible, and less expensive, causes. When I found the cracked air cleaner top yesterday, I pulled it off and found the filter was warped near the missing corner of the cover and both the filter and lower housing had some oil in them. A look at the last shop receipt shows no charges for air filters, so must not have been changed although requested. I was busy with a sick wife and a sick daughter yesterday, so I had enough time to replace the filter yesterday, but not to clean the MAFS. I have some CRC, so I will give that a try today and hopefully that will cure the codes.

If both banks are running lean, then I assume that the gas smell would not be from that. Will the ECM resolve the issue by sending more fuel and, if so, could this cause the gas smell? I am also still curious about the gas filler/gas cap and whether it is coming from there. No replacement gas caps to be found here in town, so I will either need to order a new one or, if anyone knows whether an aftermarket replacement for a 99 xjr cap exists, especially if it is a locking cap, I would be happy to know what it is.

Since I have only had the car for a month now, I have no frame of reference, but it seems to be driving normally. I do notice a slight shake at idle, however. Is that normal for this car or just another symptom of these same problems?

As always, I appreciate your help!

 

2 things to ck on lean engine for xjr, air intake tube, at the bellows over the exhaust for deterioration, rub the bellow with your hand if it crubled its bad. Or you can pull it and bend to check. Also check the part load breather for cracks too. Also clean it with a small drill bit after you remove it from the cam cover, the restrictor is in the cover. If no leaks replace the mafs
On fuel smell. No you should never have gas vapor at the cap, replace it with factory, you might be able to get 1 if you say you never received in the mail??? Never put a locking cap on, they suck, and what if the dont have the key, beside the cover locks with the alarm and you cant even get a tube in to siphon anyway. The next likely cause is the cannister close vavle sticking open, its attached to the pass side charcoal cannister. You may also want to replace the metal crossover pipe over the diff between the 2 cans if rusty looking at all since we used to replace the piep for rust flacking and sticking the close valve open,,,,where are you in tx?

 

Thanks Brutal. I will put those on my list of things to do later this afternoon. Good point about the gas cap; I completely forgot about it being locked already. The gas cap may just be wishful thinking, but I have never seen gas sit above the flap like it does in this car. Of course, I have never owned a car with a horizontally mounted fuel filler, either. Though married, the car and I are still "dating" so to speak. Lots to learn about one another, I suppose. I will let you know what I find after I get a chance to check it all out.

I'm in Corpus. Should be up in Houston later next week, although if I do not resolve these issues, the car will not be making the trip. I would rather drive than fly, but we will see. You know any good techs in this area?

Thanks again.

 

Me.........sw houston and no i have an aunt inlaw in corpus that brings her stype up here to me also

 

I may have to do the same as your aunt-in-law. I am through your neck of the woods once or twice a month for work.

 

I cleaned the entire intake from the cleaner assembly to the throttle body, including the MAFS and throttle body itself. Also cleaned the part load breather, which was completely clogged with crap. Lots of oil residue in the air intake tube, coming from the breather tube on that side. CEV is gone for now, but I will need to address that cracked intake cover with more than duct tape pretty quick. No fuel smell, but I will have to wait until tomorrow to check on it. Can anyone give me some advice on checking the purge control valve and CCV? Not quite sure what to look for and I have not found any clear guidance from JTIS cd.

Thanks everybody, I really appreciate the help thus far. You've been great.

 

if the purge valve leaks, youll get rich rough running engine, and this is not common. the cannister close valve is more likely if youre smelling fuel in the rear, and have checked the lines and orings. thats the likely and most common failure
yes i edited this post since I had to read it 3 times to understand what I wrote the first time...and I wrote it

 

When you fill your tank does it fill all the way as it should, or only tak 3/4 a tank?

Bill

 

About 50/50. Half the time it fills as it should, the other half it only fills to around 3/4. Bill, have you experienced that, too?

I will have to wait until I can get the car up oof the ground to check all the lines to/from the canister and CCV. The intake throttle body cleaning has made a difference in how the car runs, though. Since the codes for bank 1 & 2 lean/rich seem to be fairly common, I did some internet research to help with Brutal's suggestions. If there are any DIYers out there who need to do this type of cleaning, I will post a link to a great pdf description of the job, with photos. Seems like this should be standard protocol for those of you handling your own maintenance and minor repairs.

 

I found the link to this article by dumb luck the other day, but it looks like it has already been posted here. Its a great step by step for doing the procedure Brutal recommended. It takes about an hour (or less depending on how much grime your intake and tb have) and makes a big difference. The local thread is located at https://www.jaguarforums.com/forum/s...ad.php?t=10110

The link directly to the document is
www.maxperformancecars.com/dmdocuments/DiY_Document_Clean_MAFS.pdf

 

UPDATE/NEW QUESTIONS -- I still have not resolved the fuel smell issue, although I have had limited time to address it as I would like. O-rings and all connections and hoses in the evap system are in good shape, the CCV appears mechanically sound in that when I removed it from the canister, it opens and closes. I have a replacement hose for the part-load breather I plan to replace soon, although no visual problem to hose on it presently. If that hose is bad, could vacuum issues lead to fuel smell because ECM is inhibiting purge?

I have not had any MIL or CEL in some time, but I have checked the diagnostics regarding the various tests performed and everytime there is a notice that the emissions checks have not completed. If there is a condition causing the ECM to inhibit purging, could the long-term inhibition cause the canisters to become saturated and, if so, how can I check that? Just by pulling the cans and looking inside? Weighing the cans to see if above a predetermined value?

Also, today, I got a stability/traction control and ABS MIL. No codes shown by my very basic OBDII reader, but not sure that my reader will pull codes related to ABS/SC/TC. How can I read those codes, ie. are they only readable by Jag or can any service facility pull them or just need a more sophisticated reader? I have had these MILs pop up for a drive cycle or two before, then they go away for several weeks. I seem to recall the JTIS cd mentioning something about ABS/SC/TC fault could cause purge inhibition, but not sure where I saw that. I know it was not in the XJ portion of the cd. Any info on that? About a week ago I replaced a dead battery, which makes me wonder if maybe I need to chase some electrical gremlins. If anyone has some advice on where to start with that, I would be grateful.

I suspect I need to get this to a jag shop for at least a diagnostic, but none to be had here and my wife is pregnant with twins, so I am restricted from travel until June or later. I hope to resolve this in the time I have before delivery, because afterwards I will likely have no free time for a spell. I mention that only to show why I am and will be appreciative of any helpful suggestions, comments, or other remarks, and maybe even for some friendly jabs at my obvious lack of technical knowledge and skill! Thanks in advance!