67 GTX Fuel Filler Gas Leak

[TxDon]

(Warning, long post) Since I got this car I have had two issues, first being it's very hard to pump gas into the pop-open fuel door and second, I get a strong gas odor after shutting the car off when its hot. The first issue improved a little when they got new longer nozzles at the station I use although I still have to pump very slowly or it keeps tripping the shutoff. The odor issue I first put down to fuel percolating in the carb at first, especially in Texas summer heat. This past week though I think it is something else.

I normally keep the gas less than 1/2 tank but last Thursday I put more in because I was going to a car show. I filled it to about 3/4 tank, drove it home and put it in the garage. Later I noticed a really strong smell, opened the garage and put on a fan. I saw some gas on the quarter panel below the filler but didn't think too much of that since I had spilled some while fueling, common problem with that fuel door! The smell eventually cleared out. Then this morning I went to the car show and drove home but parked my car in the driveway. When I got out I could see gas on the quarter panel below the filler and it was dripping on the driveway. I got under and looked at the hoses underneath but they looked fine, the gas was dripping off the body metal. I opened the filler, there was no built up pressure but it was wet with gas inside. I wiped the gas off and left the car sit in the drive for about an hour and everything dried up. I then put it in the garage, no leaks and no smell. I did open the trunk and noticed a stain and soft undercoating under where the neck goes thru the quarter panel, so it is also leaking inside.

I'm now pretty sure my gas smell problem is the filler leaking inside and outside when I drive the car then dripping out when I park it. I'm surprised this can happen with all the vents they have and (I assume) baffles inside the tank but it also looks like I have a problem with the seals around the filler door. So I need some help:

• Has anyone else had this problem and if so how did you solve it?
• If I'm not diagnosing the problem correctly please tell what else could cause it.
• What is involved to replace the seals around the fuel door and what is a good parts source?

Thanks for any help you can provide.

 

[miller]

Don't know on the particular year, so I'll just toss this out. Is the cap vented? If you have vent/return lines, guessing no.
Might take re-installing the fill tube. Past that, sorry, can't help.

 

[miller]

Just looked in my 67 manual, covering my 67 727. Yeah, looks like vent tubes at the fill tube, that might be clogged. That would be my guess on it.

 

[Pops1967GTX]

The fuel tank may become hard to fill & or the fuel fill nozzle may shut off repeated

I also have this problem. Tank hard to fill, I can pump about a gallon, after which I have to wait for the fuel to enter the tank. I can hear a gurgling sound as the fuel enters the tank. It takes quite a bit of time to fill up.
I check fuel system for vent tube clog. System checked out find.
I think it’s The new style gas pump nozzles seem to be the problem. you have to find a good angle to put the nozzle so it doesn’t do it, squeezing of the trigger, apply the pressure & go slowly.


I always have a towel ready to catch the gas on the quarter, I hate that.......

 

[dieseldazzle]

Stock or replacement tank? I just went thru this entire ordeal on my 67 ended up the replacement tank was manufactured incorrectly

 

[TxDon]

Thanks for the replies. As far as I know its a stock tank but not sure. Pops, once you get through the filling ordeal does your filler door leak when you drive the car or after you shut it off? I'm more worried about that than the filling issue.

 

[Pops1967GTX]

Thanks for the replies. As far as I know its a stock tank but not sure. Pops, once you get through the filling ordeal does your filler door leak when you drive the car or after you shut it off? I'm more worried about that than the filling issue.

No it doesn’t leak... There’s a rubber gasket & spring then latching the door, that applies pressure to make a seal. I would check it... Make sure you have the correct one...

 

[TxDon]

That's the cap I have with the spring. I need to take a closer look at that and post some pics.

 

[ws27]

There is a seal the goes in between the filler tube and the inside of he quarter. It's a special seal that has two bumps to fit the notches of the filler tube. It is also tapered. If you are leaking inside the trunk, I'd look into that seal.

I'm glad I'm not the only one who has problems filling my GTX. I have two and both are a bear to fill. I end up on my knees to hear the gurgling in the tube. If they were daily drivers I'd go insane!

 

[TxDon]

There is a seal the goes in between the filler tube and the inside of he quarter. It's a special seal that has two bumps to fit the notches of the filler tube. It is also tapered. If you are leaking inside the trunk, I'd look into that seal.

I'm glad I'm not the only one who has problems filling my GTX. I have two and both are a bear to fill. I end up on my knees to hear the gurgling in the tube. If they were daily drivers I'd go insane!

Thanks. I had a daily driver 67 back in the early 70s and don't remember having any trouble filling it up, I wonder what has changed? I do remember having gas drip down the quarter under the filler though...

 

[TxDon]

OK, after reading your posts and researching a little more I took a good look at this setup and some pics. I have what I assume to be a repro chrome flip cap with the spring loaded seal on the original trim plate and filler neck, you can see the leak inside the trunk on the undercoating. The sealing surface for the cap on the trim plate looks kind of banged up and worn which could be part of the problem. I can see the rubber seal that goes between the trim plate and the filler neck and that does look like it could be causing the leak inside the trunk. Is that supposed to be caulked with something? My next step is to take it apart and see if it can just be resealed or if I need some new parts.

 

[Auggie56]

Just a suggestion, I have to pull the nozzle out about an inch and a half, for the handle to run, with out having to "milk the pump" on my 01' Ram. Could it be gas is going in so fast, it burps out ?

 

[miller]

Not the same thing, but a few years back had a Suburban that was a pain to get gas into. Would only take fuel real slow. Couldn't do anything about it though, since it was caused by baffles inside the fill tube. Could be something along the same lines.

 

[Dennis H]

View attachment 298914Off topic, but on my 69, I have never fueled up that gas was not spilled. Gave up. Owned the car since 1988. ;-).

 

[AR67GTX]

My 67 GTX has had the same problems. One thing I do to mine that has helped with the fuel leaking past the seal on corners is to put a healthy coating of silicone grease on the seal (dielectric grease). That has stopped any leaking past the seal on my car. I do re-apply a couple times a year. It seems to stand up against fuel reasonably well. If the surface of the fill tube is too beat up you might have to stuff a rag inside it to catch any filings and file or sand the seal surface to smooth it up a little.

But I have the same problem with filling the tank - I have to position the nozzle just right and then run it in at a slow rate.

 

[TxDon]

I pulled the filler parts off yesterday and have a major leak issue to the point that it has messed up the paint behind the trim plate. There is no sealer of any kind around the rubber gasket so I'm sure that is the problem. I've ordered a plain gas cap from Vans so I can leave the GTX parts off while I fix the paint and I may get a new seal and trim plate. I'm thinking of sealing it all back in place with Permatex Moto-Seal 1 which is supposed be gasoline-proof, has anyone used this stuff and does it work?

 

[TxDon]

Update on this - the gas cap from Van's did not fit so I sent it back. Got sick of messing with this so I took the cap, trim and gasket off again, cleaned everything up and slapped it back together with a generous coating of Permatex Ultra Black RTV. Let it cure and took it out today with a little less than 1/2 tank of gas. No leaks or odor! So far so good...

 

[AR67GTX]

Good deal - but I would still consider putting a coat of dielectric grease on the cap gasket as an extra precaution when the tank is fuller. At worse it will help prolong the life of the gasket.

 

[TxDon]

Good deal - but I would still consider putting a coat of dielectric grease on the cap gasket as an extra precaution when the tank is fuller. At worse it will help prolong the life of the gasket.

Sounds like a good idea, will do.