SalzundPfeffer

I'm trying to troubleshoot an in the car gas smell when I fill it all the way up. If I listen to the fuel start coming up the fuel neck and I shut it off before the pump automatically kicks off, I don't have as much of a smell.

Anyway, I've pulled the cover off the filler neck and have been doing some testing. I have been charging the tank with pressure using a line from my air compressor to check for leaks.

Here is what I have done some far.

1. Replace filler neck with new rubber
2. New gas cap
3. Tightened all existing connections in the filler neck area. Vent hoses otherwise look in decent shape.


I pulled the bleeder valve off to test. It is the valve circled in the figure. I lubricated it with silicon spray for good measure. The valve opens when I have it hooked up directly to my air line. No surprise there, as it's getting quite a bit of pressure.



However, with the valve installed, I have not been able to detect it open when I put air into the tank. With the larger volume of the tank, I can't build up as much pressure, but I can hear and feel the tank expanding under the trunk metal. I would think that this valve would open by then to let air into the charcoal canister. The tank is not designed to be a pressure vessel. When I take off the gas cap, there is a substantial "whoosh" of air.

I have checked and all the lines are free of blockages all the way up to the engine. It has to be the bleeder valve not opening. Is this the correct operation or should it open a lot sooner? I can't believe the tank could take much more pressure. Cyclic stress is not a good thing...

With the new filler neck and tightened hoses, I don't detect any smell in the filler neck area when pressurized. Only under the car near the transmission (transmission currently out of the car for some bearing work). Aside from the bleeder valve, any chance there is something else funny going on where fumes are getting out of the tank? Maybe that expansion tank (#5 in the photo) sitting on top the tank?

Thanks in advance,
-bp

GTSilver944

Other things: Check the gasket under the fuel level sending unit. Check to see that the overfill hose goes out of the hole in the bottom of the right rear cubby (rather than dumping into the cubby).

MAGK944

iirc venting from the tank happens through valves in the engine bay to the carbon canister in the lh fender. The valves are near the brake booster area and their job is to either:

1. Vent the displaced air/fumes from the tank through the carbon canister during fill-ups, or

2. Vent the air/fumes back to the intake and engine while the engine is running.

However, the most common cause of fumes in the cabin is the fuel level sensor seal under the hatch carpet. If you still have a problem after replacing this seal then look at the venting system under the hood.

SalzundPfeffer

The gasket for the fuel sender, is it separate from the black rubber plug that is under the little adhesive carpet square on the trunk metal? I have not pulled that off, thinking this is the gasket everyone talks about.

-bp

GTSilver944

Nope. Pull the fiberglass adhesive square off, remove the black rubber plug, then you'll see the sending unit - the gasket is between the sending unit and the tank. When you check it, pull the sending unit out slowly so the gas can drain out of it.

SalzundPfeffer

Thanks for the info. I will check the gasket.

I've found some more useful information regarding fuel smell in the cabin here:
http://forums.pelicanparts.com/porsc...eaks-read.html

Hollywood D

I had a slight gas fumes problem in my car too. The biggest culprit ended up being, one of the vent hoses was shoved down into the wheel well and not through the hole to the outside of the car. I stuck it through the hole and that pretty much solved it.

I also bought a new gasket for the fuel level sender, but there's some little tang or something on the end of my sender and I was unable to completely remove it from the tank. So I put it back and called it good.

Clean off the electrical contacts while you're in there too. Mine were pretty nasty.

SalzundPfeffer

Well, gasket looks good. Can't detect any fumes when pressurized, but still a smell. I'm thinking there is a crack in the tank on the top where the expansion tube sits. scheisse...

Time to get showered in gas. The tank's coming out!

GTSilver944

Good luck. My least favorite job, at least on an early car.

SalzundPfeffer

Really proud of myself, only managed to spill a few drops on the floor/myself. I just clamped the lower feed hose with a vise grips and pulled off the other end from the pump. Took off the gas cap and took my time filling a 2gallon can and transferring it to my other car. At nearly $4 a gallon, nothing goes to waste.

Removed the exhaust as well so now I'm ready to drop the tank tonight.

luftpirate

Let us know how it goes, I think I'm going to be doing the same shortly. I think I may have a crack, the only other thing I can think of is that plastic reservoir hiding int he pillar might be cracked. Not sure how to test the valves in the engine bay. After driving the car for an hour tonight I feel kind of sick, even with the windows down and top up I can still sort of smell it.

SalzundPfeffer

Got the tank out last night. Had to pull and tug on it a little for it to come loose. I believe there is a crack dead center in the tank near the edge of the stamped indentation that everyone talks about. I have quite a bit of grime covering everything up, so I will have to hit it with a wire brush tonight to look for more cracks.

I also need to check the long plastic expansion tank that sits on top of the tank over top the area where the crack is.

I'm starting to think about repair procedures for the crack. The previous link I posted basically said to not waste your time with JB weld. The best course of action appears to be a radiator type repair. Does anyone think that using a plumbing type solder would work? Just trying to think of options based on what tools I have on hand.

Hollywood D

It might. Does solder bond to any type of metal? I don't know if its designed to work on things other than copper. The biggest reason I think it would fail would be because of movement, pot holes, general flexing of the car when turning.

SalzundPfeffer

I think I'm going to give soldering a copper patch on a shot. Same as what a radiator shop would do and I'm always up for learning a new skill. Plus, I have all the required tools. I'm going to flush the tank with water and dry it really well to prevent any fire/explosion risks.

Here are some resources. I think I will redo the seam of the tank as well for good measure and treat any other questionable areas.

http://wiki.vintagemachinery.org/Rep...t%20Metal.ashx
http://gardentractortalk.com/forums/...as-tank-a-try/
http://www.menards.com/main/store/20...oreSolders.pdf

luftpirate

Good luck, I am about to install a rally snorkel on my roof if I don't do mine soon.