fuel tank

Helo
My fuel tank is rotten !!!
I have just got my 1st american car (iam in the UK ) - pontiac firebird 1978.
Everythig is good so far except the fuel tank leaks.
The problem is compounded by the fact that presure is building up in the tank.
Petrol (gasoline) is squirting out of pin hole in the tank.
Yes this is an issue - Are there any coatings I can paint on the tank, to reinforce it ?
Second - when I open the fuel cap I hear the pressure release with a hissssss !
I would expect a breather/vent system to release this pressure.
Where might I find it ?
Any FAQ's advice would be great :-)
Rich
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On Tue, 4 Oct 2005 20:43:12 +0000 (UTC), Tricky

There are coatings that you can seal up the tank with. Do a search on fuel tank sealing and you should find something to help you.
I did the tank on my Camaro with a sealer system. I had a hole or two that were made by a previous owner. The way I did it was to drop the tank, remove all fuel from it, wash it out. Then I made my repairs to the tank which had nothing to do with the instructions from the sealer kit, and finished the job by following the directions that came with the kit. It's been good for about 4 years now. The Eastwood company may have something on their site.
It is some kind of plastic polymer that you puor in the tank and wash/roll it around until the entire inside is coated then allow time for it to cure and put everything back together and install

I think a 78' Camaro that I owned did the same thing. I don't remember for sure though. Try a new fuel cap.

...Ron -- 68' Camaro RS 88' Firebird Formula 00' Mustang GT Vert
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RSCamaro wrote:

I was thinking of painting on the outside - but I suppose the inside is as good .
Is there not a vent on the tank ?
Rich
Rich
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wrote:

Your last post leads me to believe you should just pop for a new tank from Year One. Painting it on the outside won't fix diddly and it is NOT the same as using an internal tank coating. Asking if it has a vent on a 78 tells me you haven't even bothered to either research your car or climb under the dang thing to look.
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I glass fibred the tank on our '74 Torino. It's stood outside for 15 yrs, the rest of the car is looking very sad but the tank is still holding fuel.

tank sender. Orginally a 6 cyl, it had an evap canister but AFAICR nothing else went back to the tank.
HTH
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Mitch - 1995 Z28 LT1 M6
terminal snipped-for-privacy@sand-hill.freeserve.co.uk
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Here's a few hints.
1: Best to replace the fuel tank with new if you can get it imported. You'll need to save the filler neck as replacements don't come with one. Ther 1979 - 1980 Firebird fillers necks were longer then the previous years due to the redesign of the tail-lights and bumper. Which leads to idea # 2.
2: After running the gas tank 'dry' and getting all the gas out, take it a shop that restores radiators or find an old (relative speaking as some folks think anything post war is too new, joke) auto restoration shop. Have them 'boil out' the tank which will remove the rust and expose all holes. They can then weld the tank back together. That is if they agree to it. About the filler neck, had a 79 that leaked at the top of the joint between the tank and neck. The reason is pressure of the gas pump handle resting on the neck during refuling cracked it. Found out when it was replaced with a 'new' old tank out of a 78.
3: While ordering the tank, order new hold down straps. Safety first. While the tank is out, use a POR 15 to paint over the trunck floor. This stuff sticks to rust and metal like glue to paper. Its made in New Jersey (USA) but maybe sold in the UK, do a Googly.
Now about the gas tank pressure. Two things. One, the gas cap vent could have failed. Get a new cap. If your need OEM, there are lots web sites supplying GM parts. Its a common part. Else, maybe your local auto parts store ight, agian don't know the easy of parts access over there.
Two, the charcoal gas vapor recover system canister needs replacement. First replace the gas cap, then all the rubber hoses to the canister. If that does not cut down on the pressure, then replace the canister. That verywell will be a OEM part. What happens is the canister captures gas vapors from the tank. Then, when the motor is running, the canister is purged by the vacume line and burned in normal operations. What is happening is the vapors are not making it to the canister.
Check all the lines for pinches. After all this it still happening, it could be a rusty cloged line from the tank to the canister. The fuel system is simple, tank, pump, carborator, vapor emission system (canister). Not like fuel injection systems where there is a pressurized fuel return system. What the injectors don't need goes back. Not so with a carborator. The 1980 still had a caroborator, but some of the metering was computer conrolled.
SInce your dropping the tank, looking into replacing the lines as well. After 25 years and knowing you get a bit of rain over there, your going to get rust!
Had a number of TAs over the year (1975, 1978 with the outlaw Pontiac cam 400), 1979 and now a 1995.) Read about the 79 and 95 at my web site:
http://hometown.aol.com/seppburgh2/myhomepage/index.html
Let us know how this turns out.
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snipped-for-privacy@handmade-f9.co.uk says...

I would look into purchasing a new gas tank. There are very good reproductions on the market that are direct fit and affordable. I'm not sure if a painted or "sealed" tank is going to pass the strict vehicle inspections you have over there.
Since 1971(and 1970 for California) the F-body has had a sealed fuel EVAP system. There isn't a vent in the gas cap. The venting is done through the charcoal canister in the engine compartment. If the car has sat for a long time its possible that old "petrol" varish has plugged up the EVAP line running to the front of the car. I would try disconnecting the rubber hose at the charcoal canister and blowing compressed through the line. Make sure you have the gas cap removed when you do this.
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Dennis Smith
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Thanks Dennis for the clarification. Its been over three years since I sold off my 79 TA for the 95, so am starting to forget the finer details. I agree a new tank is the best solution for safety reasons. Which is one of the reason the 79 went. The trunk floor and tail panel both needed replacement. Could not justify putting the family into a situation with a rear end crash (the Ford Pinto cames to mind.)
On the EVAP, maybe leaving it disconnected would be a way to test it. No tank pressure, found the source of the problem.
Thanks for updating an old timer!
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