Greetings All,

I have been reading some threads on gas smell in cabins but I am not seeing a defined hierarchy of trouble shooting. I hope the forum members can give me some direction.

Basics:

1. Gas smell is in the cabin and the trunk when the sunroof or windows are open thus obviously drawing in the fumes from somewhere. No fumes when A/C is on and windows/sunroof closed. I have gotten the gas smell once or twice on hard corning on a Interstate Clover-leaf.

2. I was getting a "Check Gas Cap" warning and a CE light after driving the car for about 20 minutes. I replaced the gas cap, cleaned the filler rim (where gas cap seats) and the problem DID NOT change.

3. I have removed the trunk materials and visually inspected the hoses and tank. I see no area of leakage. Gas mileage seems normal so I don't think I am loosing gas. I have blown into the filler neck (using a straight 8" coolant hose - great trick btw). I could hear the gas bubbling but could not identify by smelling around tank where fumes could be leaking. I am assuming vapor leak to be small as the gas smell does not persist in cabin or trunk very long.

4. I have looked under the car for any gas leakage or smells and could not find any.

5. The gas tank appears to be the original (based on date codes) but some of the hoses are attached with nylon straps (tight) instead of the original Corbin clamps. I assume fuel pump has been serviced/replaced.

So what would be the best place to start trouble shooting? I am not adverse to taking the tank out and I know this will probably be required.

If this is the case I would appreciate a list of what I will need to order so I will not have much down time with the car.

Thanks for any comments.

 

Read the OBDII codes first.

 

Something like Fuel Pressure Leak - Major.

I think the "Major" sets the CE light off. Just a brief pressure drop - "Minor" - does not set CE light off.

 

Do you have the code number(s)?...there are several codes for the fuel evap. system, and this will save time chasing the wrong problem.

 

Diagnostic Code:

P0455 - Evaporative Emission System Leak Detected (large leak)

When the Check Gas Cap message comes on (only after 10 miles of driving at highway speeds), if the car is turned of within about 5 minutes and restarted the message goes out. If the car keeps running for more than about 5 minutes the CE light comes on too. And of course that has to be reset.

 

Change the gas cap.
P0455 Have you searched for it?

1 Fuel cap off
2 Fuel cap seal defective (the most common one for this code)
3 EVAP system leak
(canister damage, pipework damage)
4 EVAPP valve to ECM drive circuit:
open circuit, short circuit, high resistance
5 EVAPP valve power supply circuit: open circuit
6 EVAPP valve to engine purge pipe damaged /
blocked / leaking
7 EVAPP valve operating vacuum hose leak /
blockage
8 EVAPP valve failure
9 Fuel tank leak

 

As per my original post:

"2. I was getting a "Check Gas Cap" warning and a CE light after driving the car for about 20 minutes. I replaced the gas cap, cleaned the filler rim (where gas cap seats) and the problem DID NOT change."

I am trying to figure out 3-9. I thought telling symptoms might get me a little more pointed direction as I am not very experienced in this area.

I smell gas vapors - I figured there is either a small gas leak or a seal is allowing vapors to be leaking. I doubt the gas leak as the smell does not persist.

While the list above are the possible causes I was hoping for a list of probable causes based on other owners experiences.

 

I would definitely start with an instpection of the hoses into, out of and between the rectanglular black plastic charcoal canisters under the car near the area between the rear suspension. Sometimes they have visible cracks or a plastic connector may have broken.

 

Trying to get back at this. All the undercarriage evap. control components look fine. Certainly no gas leakage and I cannot even isolate a gas smell.

I can still smell the gas fumes in the trunk tho they are never very strong and, as stated before, don't linger.

I am afraid that I am going to have to take the tank out and inspect/replace the gaskets that are around the evap. "bundle" on the top of the tank.

Has anyone identified a problem area with any particular gaskets that tend to leak vapors?

Also, mine is a 2002 XJ8 and the tank / evap. "bundle" is different than many of the diagrams I have viewed.

Does anyone have a parts diagram that will show the part numbers?

Thanks.

 

Robert, you may wish to check the emissions purge valve situated under the bonnet/Hood, directly behind the TB on the firewall.
A round plastic device with an electrical connector and a couple of vacuum pipes.
This may have failed and causing a pressure build up back to the tank, which may explain why you are smelling vapours in the boot/trunk....and yes will most likely involve the emisions control on top of the tank.
The system working correctly, there should not be any vapours obviously ;o)
You have checked the carbon canisters and in the same area is the fuel filter...no sign of leakage or weeping?
While there, using a bright torch, look above the IRS carrier at the base of tank on drivers side where two pipes enter the tank.
These are equipped with quick disconnects....check for any weeping.

 

Thanks for your comments.

I have checked all under the car for any vapors, weeping, gas leakage, etc. and have found none. Also I have never detected any gas vapor smells under the car or hood. Additionally, there is never a lingering smell and that points me to it just being a vapor, as opposed to a fuel, leak.

Your comment on the Emissions Purge Valve under the hood is interesting. I am familiar with this component but have not considered it culprit so far.

Is there a way to trouble shoot the Emissions Purge Valve or is it just a replace it and see what happens affair?

Thanks.

 

yes...i think xj8 first one to suggest LOOKING UNDER THE HOOD! JUST HAD MY PURGE VALVE CHANGED.....had same code come up.....they did a smoke test to detect leak.....but not gas leak per se.....i would definitely check out the purge valve

 

[QUOTE=

........Your comment on the Emissions Purge Valve under the hood is interesting. I am familiar with this component but have not considered it culprit so far.

Is there a way to trouble shoot the Emissions Purge Valve or is it just a replace it and see what happens affair?

Thanks.[/QUOTE]

Gents, the purge valve seems to crop up more and more asa culprit as these cars age along with components in the emissions system.
There really isn't a way of testing it, it's one of those items where it either works or it doesn't. ;o]
But quite often lately it has been found to be a culprit.

 

Well, I finally got back into the project today. The gas vapors are still identified as coming from trunk and into back seat as described. The vapor smell seemed to be towards the top of the tank.

I took the tank out today and found some interesting things. Previously someone had repaired something with/in the tank and took/tilted the tank incorrectly thus bending one of the gas lines under the car. It did not appear to be leaking tho.

I strongly suspect that one or more of the gaskets of the evaporative flange housing is somehow leaking fumes when the tank is under pressure. This in turn is throwing the P0455 code. All the gaskets appear to be original and the components associated with them wiggle easily. If it's not the exact problem it demands attention anyway and is a good place to start.

Below are some pictures of the flange top assembly and components:







Below are examples of the components and the gaskets they need:





I also found these parts in the gas tank:



I figured out that the hook goes on the fuel level sending unit but I am not sure where the black grommet goes. I am also not sure what the hook does. One of the wires going to the sending unit is a bit frayed but I don't think this is causing a problem. The wires are submersed in gas and connections are splashed constantly. Still, I will probably go ahead and replace that unit while I am in there.

I also can see the two "O" rings in the fuel line quick disconnect fittings where the gas lines connect to the tank from underneath the car:



Can these be replaced?

I want to replace all the gaskets and hoses while I have the tank out. I would appreciate it if someone has a parts list diagram they can share. Also, who are the best OEM Jaguar parts suppliers in the US these days?

Thanks for your help.

Robert

 

Hello Robert....after looking at your pics and reading your description, it seems
some one has been doing a messy job of previous repairs ;o]
Sopme people sem to take the attitude....why do a good job when it's easier
to make a hash of it.
Obviously these components have been disturbed and none of the gaskest and 'O'
rings have been replaced.
The vapour control unit on top of rank would it seems be the main culprit.
I reckon with new gaskets and careful assembly, you should fix the problem.
Use a light smear of petroleum jelly on all gaskest before assembly.
Those two rings in the quick dissconnects are replaceable and should be replaced every time they are disturbed....it doesn't help that some plonker bent one of your pipes.

 

Most of the good places like Parts Geek, Amazon, Welsh Enterprises, Jagbits, Motorcars ltd etc will have the bits.
Christophers Foreign Car Parts seems pretty popular.
Coventry Auto and rock Auto are also good.

 

Thanks for that help!

I still am interested in seeing the parts diagram so I can explain the parts (and better yet, have the numbers) when I call one of the listed providers.

And just how do you get those O-rings out of the quick disconnect "tube"?????

 

The black rubber piece in the photo is the fuel pump mounting rubber - part# NND6025AA Look at this parts list on jaguar classic parts website (see item marked #4 mounting rubber):

Fuel Tank-V8-Supercharged-From 2001My - Parts For XJ Series from (V)812317 to (V)F59525 (X308) | Jaguar Classic Parts UK



This is a photo of the sender unit in jaguar forum thread on repairing the sender unit - shows the hook on the sender unit:



Here is the thread weblink (look at post #4):

https://www.jaguarforums.com/forum/x...bwoofer-70631/

Jim Lombardi

 

Thanks Jim,

That diagram was helpful. BTW, is that diagram part of the set that you are offering as a download for the entire parts manual?

It is interesting that I have not been able to find a diagram that actually shows all the components of the evaporative flange as pictured in my photo. What does one do in that case? Do I have to call to get individual part numbers for the O-rings, gaskets, rubber fuel line connectors, etc. that my unit has?

And do you know how you replace the "stuffer pins" (aka quick disconnect orifices)? At first I thought you would just replace the two O-rings in each "pin" but the diagram looks like you replace the whole "pin" assembly.

 

Here is another fuel tank components diagram - Evaporative loss flange parts - on the Jaguar Classic Parts UK webpages:

Part no. NNA5954AA | .Evaporative loss flange parts from Jaguar Classic Parts UK

Looks like all the component parts to the Evaporative Flange Assembly for the fuel tank.

Jim Lombardi