Gas Tank

car911 · 09-04-2001, 08:16 PM

85 (old style) 944.

I have a leak in the top of my gas tank and it does not seem to be coming from the filler tube or level gage but somewhere else around the top of the tank. I removed the carpets and I can see and smell the gas leaking when the tank is completely full - but otherwise not - so the leak must be at the top. (I am now only filling the tank 75-80% full and the leak seems managable).

My local mechanic (not Porsche specialist) tells me I need to drop the transaxle to remove the tank for inspection.

Does anyone have any alternative ideas for tracking down the leak? Any way of inspecting the top surface of the tank without dropping it? Is it possible to cut the sheet metal in the hatch floor on top of the tank?

Other than the filler tube and the fuel level guage, anywhere else where the leak can be occuring? I really can't see how a crack can occur spontaneously - there have been no accidents or bumps of any kind.

Any suggestions or comments would be welcome.

AFJuvat · 09-04-2001, 08:26 PM

Wow, that is a tough one. The gas tank is not the easiest thing in the world to remove, but it is a much better option then cutting sheet metal. (IMHO)

You stated that gasoline is leaking inside the car? The only place I am aware of (I may very well be wrong) inside the car is the fuel level sending unit - you may have a bad one, and/or the seal for it is shot.

AFJuvat

newoldguy · 09-04-2001, 08:58 PM

Are you sure the fuel lines to the sending unit and/or clamps are OK?

car911 · 09-04-2001, 10:36 PM

I pulled back the carpet and removed the protective sheet metal surrounding the fill tube. You can see where the fill tube is joined to the gas tank by a rubber hose but the rest of the tank is hidden underneath the sheet metal. I looked carefully and there is no sign of leakage from the rubber hose. The clamps seem tight as well. Perhaps I should try replacing the rubber hose and clamps anyway?

I really find this puzzling. I especially can't understand how a leak can develop at the TOP of the tank. Any insights appreciated. I would like to avoid a major dismantling job if possible.

car911 · 09-04-2001, 11:03 PM

Quote:

Originally posted by newoldguy:
Are you sure the fuel lines to the sending unit and/or clamps are OK?

I wasn't aware there are fuel lines to the sending unit? I thought just electrical connections???

MAS · MAS's Garage

Check the 944 FAQs. If I remember correctly one topic dealt with a problem endemic to many 944's... namely, a small leak, or break around the filler hose area.

-MAS

John_AZ · 09-05-2001, 09:50 AM

On the top of the tank ('87 924S) directly across from filler tube under sheet metal is a plastic vapor (?) recovery (overflow) tube about a foot long connected by fuel hose. The tube lays in a cavity that is not accessible from the access cutouts under the carpet. This area is also prone to thin upper gas tank bends and crimps that can leak when stressed.
Unless you remove the rear transaxel and drop the tank the only way to replace the hose and check for stress leaks is to cut (horror) the sheet metal deck. I have not found a permanent gas tank repair that will hold by the stress cracks. If you have a leak in this area you will have to have the tank welded-OR-use J-B Weld or similiar product. Good Luck

88_944 · 88_944's Garage

I just had a gas tank leak, did you look under the tank and see the gas runing down the tank? This is what I thought but it turn out to be the tank to fuel punp line had a rip in the hose. Take off the bolt that holds the tray of the fuel pump and see if the hose is ok.

It's the #2 hose on this picture. (I change #2, #10 and #15 hoses.)

------------------
PORSCHE There is no Substitute!
My 944 Site! http://www.skybusiness.com/dean/

[This message has been edited by 88_944 (edited 09-05-2001).]

car911 · 09-05-2001, 01:46 PM

Quote:

Originally posted by 88_944:
I just had a gas tank leak, did you look under the tank and see the gas runing down the tank? This is what I thought but it turn out to be the tank to fuel punp line had a rip in the hose. Take off the bolt that holds the tray of the fuel pump and see if the hose is ok.

It's the #2 hose on this picture. (I change #2, #10 and #15 hoses.)

thanks for this detail. However, the leak is present only when the tank is full and disappears as fuel is consumed - last time I actually filled the tank, after about 50 miles - so probably less than 5 gallons. This does not sound like a fuel line problem to me but rather a leak in the very top of the tank somewhere. Or is there some way the fuel line only with a full tank but not other times???

car911 · 09-05-2001, 01:51 PM

Quote:

Originally posted by John_AZ:
On the top of the tank ('87 924S) directly across from filler tube under sheet metal is a plastic vapor (?) recovery (overflow) tube about a foot long connected by fuel hose. The tube lays in a cavity that is not accessible from the access cutouts under the carpet. This area is also prone to thin upper gas tank bends and crimps that can leak when stressed.
Unless you remove the rear transaxel and drop the tank the only way to replace the hose and check for stress leaks is to cut (horror) the sheet metal deck. I have not found a permanent gas tank repair that will hold by the stress cracks. If you have a leak in this area you will have to have the tank welded-OR-use J-B Weld or similiar product. Good Luck

Would you know whether the 87 924 has the same fuel tank set up as a 85 (old dash) tank??? Does anyone know whether the 85 has this overflow tube? Any diagrams of the tank system itself?

overkill · 09-20-2002, 01:10 PM

Yo, can you smell the gas after the car sits for a long period of time? What I'm getting at is that if your tank is FULL and you make sharp turns the gas will spill over the top of the tank. I think it is the top of the tank, anyway gas will spill out on hard cornering. I only fill my tank up about 3/4 to prevent this from happening.

SoCal Driver · SoCal Driver's Garage

This is the early style steel tank and hoses. The vent hose leaks where I have indicated. You need to remove the cover over the filler pipe, cut the hose at the bend and insert a copper 45 degree elbow and clamp it. These cloth wrapped rubber hoses tend to embrittle and crack at bends.

You notice there are three other connection points for this hose.

thamlin000 · thamlin000's Garage

I'm having the same problem. My car smells like gas inside after it sits for a while. To combat the problem, I too, fill the tank up 80% of the way.

John_AZ · 09-23-2002, 02:47 PM

Followup:

On SoCal's tank picture the area of my leak was below the tan plastic overflow tube in the hollow (above the "e" in the word filler. There were two 1/2 inch cracks at opposite sides. J-B weld did not hold. Permatex gas tank sealer-a epoxie putty material has held, about $4 at Autozone. I reinforced the patch, about the size of a quarter with fiberglass cloth. It looked like a thin Oreo cookie. If you use this method remember that the overflow tube has to still fit in the grove so don't make it too thick.

John_AZ