Fuel smell in the cabin of my 1986 XJ6

Hi Folks how do I get to the plenum camber flaps , I took out the rear seat but I could not get to them, I would like to renew the foam, I smell gas fumes in the car

Simple, the tray is accessible from the boot.

This might not be the reason for you smelling fumes. There is something fuel related in the C pillar on federal models.

I had a fuel smell in my '86 cabin. It was caused by a very slight weep in the end of the fuel pump. Replacement pump sorted it.

I had already fixed all of the cow bells.

Philip, 4.2 Sov, S3 NZ

You must determine if the smell comes from the engine compartment or the boot/trunk.
Fixing the flaps, if this is the case, will just lessen the effect, but you must find the cause.

Fuel vapors recovery system.

Windows closed and fans running, Dieman…?

xj6 85 Sov Europe (UK/NZ)

The back of the back seat has to come out as well as the stuff in the boot that backs onto the back seat. These flaps are little rectangles of sheet metal with head liner material covering them & some plastic glued to the car and the metal rectangles. They blend in very nicely (read hard to spot if you don’t know exactly what you’re looking for. Open and close the door, you’ll hear them tinkle like a cow bell. But I don’t think that’s the issue, unless the boot wreaks of fuel when you open the boot.

The return fuel piping and hoses are just below the C pillar/ There is also a additional piping that runs up the C pillar, then down under the parcel shelf inside the boot. It’s not uncommon for the solder to give way on the piping in the C pillar. I have a series II that the PO did some creative plumbing in that area. it’s another one on my todo list.

This is what I’m on about

Did something change? Can you please check my previous post, and tell me why that wouldn’t work - it did, for me… of course the lower two flaps are hidden by the trunk carpeting but the trunk would have to reek of fuel if they were at fault!
The c pillars are the best guess, right? But Dieman, it is important to check for fuel leaks to, at and from the engine. Ideally check while the engine is running, so you can see it before it evaporates.

I had noticeable fuel smells in the cabin smells three times in my Series III XJ6s. Twice it was from leaky fuel tanks that was most noticeable with the sunroof open and the third time it was a fuel leak in the small (3"?) fuel hose at the very front of the engine.

I have fixed the “cowbells” problem on all three of my Series III XJ6s by removing and replacing the failed headliner type sealing material on the flaps. There are flaps on the Extractor Tray beneath the rear parcel shelf as well as in the panel at the very front of the trunk (boot). All are accessible through the trunk but a fair amount of disassembly is required to remove the Extractor Tray.

There should be lots of info in the archives about this under “cowbells”, which is how some folks refer to the metal to metal sound that tge flaps make when the sealing material fails.


Sorry my mistake David, It would help with the smell, but I don’t think that’s the whole issue. Unless I misunderstand what part you’re talking about the “cow bell syndrome” are little flaps to allow the air to circulate out of the cabin. as well al know the series III’s don’t have “vent” only air in the cabin is through the air con / heating system and the window down.

At the risk of being a Debbie downer, I would do a bit more investigating cause I think root of the fuel smell may be a leak lurking somewhere else in the back.

Totally agree. I just recalled that the extractor flaps are easily accessible, but yes, they vent to the outside so exhaust fumes are the only thing they could possibly let in, and of course they should be either closed or allowing air out, not in. The best suggestion is to check at the engine first, and check if the trunk smells. If neither, the C pillars or the tanks leak, which one should smell from the outside, right?

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No Leaks anywhere I even put new hoses from the charcoal canister. and purge valve, I only smell a hint of fuel as I drive with the windows up, no leaks in the trunk area

Check for telltale wet marks on the lower valance panels beneath the fuel tanks that indicate a leaky fuel tank.

I had these signs twice and was in denial that I had a leaky fuel tank until I removed the tail lights, took a whiff, and got strong fuel smells there. Then came the day that I saw an unmistakable fuel stain beneath the car after it was parked on asphalt for a day. Then I learned how to remove and replace the leaky fuel tank.


Me too. mine came to life when I was at the filling stating. I was putting petrol in at the top, while it was going out the bottom. Bad day all around.

Not so, Mark…

The fans build up overpressure in the cabin - which forces the ‘cow bells’ to open to get rid of stale air via the boot with the windows closed. This is a fairly standard philosophy on most makes; if air is not vented out, fresh air cannot enter. The ‘cowbells’ are spring loaded closed to prevent backflow from the boot…

Opening the windows/sunroof may give underpressure allowing eddies to enter cabin, which may bring odour - from your own car or others. Which is why I asked if he ran with windows open…:slight_smile:

And with defective ‘cowbells’ sealing; air may be drawn from a smelly boot…

xj6 85 Sov Europe (UK/NZ)

I don’t think so.
And I think what he meant to say is that there are no “pull air” vents, so the only ingress points should be between the wipers and with open windows. And if the fans run the cabin has a slightly higher pressure and thus the air can only come from the fans and blow out anywhere else. Nevertheless, smells can get inside at the C pillars and all vents; and we know fuel reeks.

I had my shock moment (the tanks look good!) when the RH changeover failed and the left tank was overfilled… big puddle. Luckily, I caught it.


Maybe I didn’t word it correctly. The above statement is 100% accurate. My only yard stick is American cars. That being stated. with an domestic auto, the climate control provides some functionality of by passing the heat & cooling by putting the control on vent.

In a Series III XJ (atleast none of mine) have that ability. There isn’t a kick panel vent (like on the Series I & II) to allow outside air to enter the vehicle. without going through the A/C system. That is what I meant.

With open windows and at speed, David; airflow does strange things - like keeping aircraft aloft…:slight_smile:

Open windows just disables the built-in, and effective, ventilation system…

xj6 85 Sov Europe (UK/NZ)

Ok thanks that did it , I changed the Hoses, refoamed the flaps and I don’t smell anything anymore, after I did the flaps there was still a Gas smell and than I changed the hoses in the diagram and she does not have the Gas Smell anymore, keeping my fingers crossed ----Thanks Folks for all of your help

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Hi Paul
Some years ago I had a situation on our '87 XJ6 in which a fuel smell filled the cabin only when driving the car downhill. turns out a fine separation had formed on the front of the top seam of the tank causing leakage going downhill. Here’s a separate unrelated question to ask you: the clutch on the a/c compressor on the same vehicle has failed. I suppose after 12 years I shouldn’t complain. The question now is, which would be a better replacement, a new GM Harrison A6, or a lightweight aluminum replacement from Retro Air? I spoke with ‘one of the usual suspects’ vendors yesterday, who said they will only sell the GM unit because there were too many lightweight defective units being sent back by unhappy customers. What is your opinion on this? I’m curious to hear your thoughts on this matter. Thanks

Since you are so desperate to know… :smirk:
The A6 is a hefty piece of iron and won’t fail that easily. Most upper end cars from the 80s had them and I‘d look for reconditioned units, although the newer ones should be better. On fuel economy. I‘d use what was in there from the factory for originality and maybe do a search for common AC failures (Sanden/Harrison).