gas odor with full tank Topic is solved

[Clemens]

For a while, I've had a fuel odor from the gas tank area with a full or half full tank. as soon as the level drips, the smell stops. I popped the fuel pump cover and nothing seems suspicious there. What's next? remove the right rear wheel liner/inner fender and look for a rotten hose?

[MoVolvos]

For a while, I've had a fuel odor from the gas tank area with a full or half full tank. as soon as the level drips, the smell stops. I popped the fuel pump cover and nothing seems suspicious there. What's next? remove the right rear wheel liner/inner fender and look for a rotten hose?

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First thing to check is the rubber seal of the gas cap and the sealing surface where the cap meets the filler neck. If dirty stuff a rag in hole and use a 4 to 600 grit sand paper in circular motion to clean. Clean and vacuum before rag removal. Also, a very very thin film of silicone on the gas cap seal before checking for fumes on a full tank. You can also lightly film the gas filler neck area where the gas cap meets.
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[scot850]

What Mo Volvos suggests is great advice. Sometimes the simple stuff is all that is needed. Even swapping the fuel filler cap. I had to gently re-profile a filler neck on a friends car as they had somehow managed to dent the top edge.

Seeing a leak on top of the tank is also hard to see sometimes, including the seal on the fuel pump leaking.

I have a friends car to 'smoke' when they can make time to leave the car with me. It has a evap system leak which I am sure is above the tank where I can't currently access as there is a removable cover that can't be removes over the pipes. I may have to drop the tank eventually, no matter what.

I bought a cheap smoker off Amazon with additional plugs to allow it to build pressure by plugging pipes to atmosphere.

One quick question. Do you 'top off' the tank when you fill the car. So when the pump cuts off, do you try to add more fuel? Don't! In the newer P80's (not in fairness the older -98 cars with the carbon can at the front) it is possible to flood the carbon canister doing this which can lead to hard filling and fumes.

Neil.

[erikv11]

Get your head under the car and look around for stains on the side(s) of the fuel tank. That has shown me two different kinds of P80 leaks - when a hose on top of the tank was leaking and when the fuel pump seal was leaking. Especially take a look when the tank is full and it is smelly, may even see wet stains if you have that kind of issue.

[Clemens]

Thank you, gentlemen!

I will follow your advice. I don't top off the tank. I will fill it up and look for wet stains on the side of the tank. And, since I have enough p80s, I might as well swap the fuel cap after cleaning the neck inlet.

[atucker1]

You may have a very common problem with these 850s, which is a leaking vent hose on top of the gas tank. Unfortunately, the tank must be removed to replace the hose, which is a bit of a pain. As always, RobertDIY has a great video on how to do it. An easier solution that may work is to only fill the tank to a gallon or two below full, but might not work for you depending on the hose condition.

[rguzz]

Second leaking vent hose if nothing else stated above found.

[Clemens]

cleaning the filler neck and switching fuel caps did the trick. Over 1000 miles and still no fuel odor.