Recently I have had fuel smells coming from the trunk of the car. I bought a cheap sniffer on eBay and it appears it is coming from the sender. I removed the gasket (URO brand) and it looks too soft and pliable. I don't know what it's made from, but I'm not sure its a good idea to use that gasket brand here.

Does anyone know the thickness that this gasket should be? I have measured it at 3mm from another one I have. (RockAuto was selling them at $0.98/each and I bought a few) I should either buy an OEM gasket, or a small sheet of Viton and make my own?

 

It isn't so much the thickness as its ability to seal, typically some form of rubber ring, I think these sender seals are pretty generic, at least they were on most Leyland vehicles at the time. Pretty much any triumph / austin / morris / jaguar would have these - thin paper type gaskets they aren't so 3mm sounds about right. You need to be sure to get the ring tight without distorting it or the neck that it fits into, if it reaches the stops easily it isn't tight enough. For the record also my XJS has always smelled after it has stood for a while.

 

What is the EBAY site you purchased the sniffer from? I am interested in purchasing one.
Thanks

 

Apparently it was an Amazon purchase.

I have a 1/8" piece of Viton on order from eBay. I'll cut it to size and see if that doesn't resolve the problem.

UPDATE: After filling up the gas tank, and using the sniffer again, it's DEFINITELY coming from the fuel filler gaiter. I have ordered a new one, with a new o-ring. eBay has some kind of "aftermarket" gaiter that is advertised as being more robust, and thicker. Basically, I ordered part numbers CAC7509 (o-ring) and CBC87033 (gaiter)

Will report back.

 

I had this issue a couple years ago. Drove me nuts as I changed the sending unit gasket, the hoses from the tank to the sump to the pump to the filter. I even changed the tank and the filler neck gasket. And still I had fuel odor.
Last summer I sprang a leak in the fuel line hose after it leaves the trunk and routes up over the rear suspension cradle. There are metal pipes that connect to rubber lines. Those rubber pieces were over 30 years old and developed cracks that under pressure when the fuel pump was on leaked...and it was rapidly getting worse.

Of course NOTHING is easy working these cars but eventually I was able to replace the hose without dropping the rear suspension cradle. Dropping the cradle would obviously make things much easier but then dropping the cradle is not a piece of cake either.

 

BradsCat, that is NOT news I wanted to hear, but thank you. I am afraid I'll be chasing ghosts for awhile. I bought the sniffer hoping that would help find the problem.

I have the gaiter and o-ring on order. The sniffer is definitely sensing odors coming from that assembly. I stuck my hand in there, and all feels well. I stuck a camera in there and all looks well. There was a loose zip tie on the vent line connection, which I replaced with a hose clamp, but does not seem to have helped.

 

URO = U Replace Often
They only sell junk, avoid putting anything made out of rubber from that brand.

 

I will see if I can replace the hose that connects the Fuel Tank Evaporative Loss Flange....and whatever other hose(s) come out of the top of that tank... is it even possible to do that without removing the tank?

 

Has a similar odor problem.. Found out the sending unit was leaking. Wiggle the connector and see if fuel comes out.

 

its certainly not the sender. The sniffer is now happy with a new gasket there. (It’s URO so I don’t know how long it will last.)

The sniffer goes nuts at the filler tube gasket…..and…..apparently on the opposite side of the trunk, over by the battery. I’m starting to think it might be coming from the top of the tank….