My gas tank is behided the seat and if i top it off you can smell the fumes. It didn't have a vent on it that i saw . have yall got any idea how to vent it. It ain't got any holes so you couldn't smell gas. It only does it if i fill it up. I know what someone is going to say. DON'T FILL IT UP !!!!! BUT REALLY CAN I VENT IT SOME HOW ?

 

With or without a vent you wouldn't think you could smell gas fumes in the cab unless there may be a place on the tank or fill pipe which is letting the fumes out in the cab. I wouldn't smoke in the cab till this is corrected.

 

On the stock tank the outlet is on the bottom of the tank, and the cap is vented. If you're getting fumes in the cab it may be from the vented cap outside the cab, the fuel guage sender, or the filler hose is seeping. I plugged my bottom outlet and changed to a top mounted outlet. I used a standard hot rod shop filler tube and ring kit that has two threaded holes, one for the outlet tube and one for a vent. In the center of the photo you can see the 90 degree outlet with the white teflon tape on it. Right behind that is the roll over valve/vent tube. I used 3/8 steel line for the outlet, and rubber fuel line for the vent. Both run along the side of the tank and out the bottom of the cab on the inner side of the frame so they can't get crushed in a t bone. The vent line has a fuel filter on the end and it the line runs away from the cab, towards the bed to keep the fumes away from the cab. I now have a non vented cap. You can also see that I boxed around the tank with MDF and the cover behind the seat is fiber glass with gray carpet covering. My truck's not running yet, but with the outside vent, non vented cap and enclosed tank I hope I've eliminated the cab fumes.

 

I try not to fill so that gas is in the filler tube. Even if I do, with new rubber on the fill tube and new gasket on the sender, I get no fumes.

 

When I had my tank cleaned by a radiator shop I had them weld a small vent tube to the tank. Then I ran a hose from this tube through the floor and under the truck and used a non-vented cap. I never had any gas smell or fumes in the truck at all after this...

 

I had exactly the same problem - it really smelled in there especially when you filled up with gas - the fumes were overpowering. I would recommend going with a non-venting gas cap & put in an extra rollover style vent as Vern suggests above - that goes outside the cab. I then would take a hard look at the sendiing unit gasket on the top of the tank - that was a problem for us - you can replace the gasket.

In the end I was kind of freaked out by the whole smelly gas tank in the cab thing & we moved it out back under the bed. It's not that hard to do - though it makes running your exhaust out the back a bit more complicated.

Ben from Austin

 

If the neoprene filler hose is cracked, and/or the tank has a NON-vented fuel cap, and/or if the cork gasket that fits between the tank and the unit has shrunk...you will smell gas in the cab.

All trucks without Evap Emisssion have a vented fuel cap, and since Evap Emission wasn't introduced until 1970...

These tanks vent thru the fuel cap, if a non vented cap is in place, that could cause the fuel tank to partially collapse. Not pleasant!

Consider: When the tank is filled on a hot day, the heat cause the gasoline to expand...causing fumes to waft everywhere, and gas will usually seep past the fuel cap.

 

DALE I HAVE THE SAME CONDITION, AFTER REPLACING THE RUBBER FILL TUBE AND SINCHING IT GOOD,AND REPLACED SENDER AND GASKETS I STILL HAVE A SLIGHT ODER. i FIGURE SINCE THE TANK IS NOT BAFFLED IT MUST BE THE FUEL SPLASHING AGAINST MY NEW LOCKING GAS CAP AND RUNNING DOWN THRU THE CAB SEAL,WHAT THE HECK ITS PART OF THE CHARM, FAINT AND DONT BOTHER ME. I JUST REALIZED MY CAPS BUTTON IS ON, I DIDNT MEEN TO YELL AT YALL. (JIMMY)

 

I'm guessing thats the trouble. THE GAS CAP !!!!! How do i know if its a vented cap ? I had a locking cap from classic haulers but it was a pain to get off and on so i bought a pretty stainless one off ebay. All the gaskets/ hoses/ claps are new. I put some silicone around the sending unit today when i got home anyway. Gues i'll go back with the locking cap and see if that helps. THANKS

 

Or may be the parts store could take a look at it and tell you, I was thinkin it might be worth taking a look at your paint also to make sure its not affected by any gas, just a thought. Good luck (JIMMY)

 

If it was sold as a stock replacement cap then you can probably assume it's vented. I forgot where I bought my non-vented cap but they are not as easy to find as the vented type. Besides, if it is non-vented and you have a stock gas tank then you would have had problems with a vacuum building up in the tank and choking the engine by now.

 

I seen one modification where the owner welded a steel line in the top side and near the top of the filler tube, then attached a rubber hose down through the floor. He said just weld the line almost flush inside so the gas pump nozzle doesn't hit. As you know the filler tube is easy to remove and weld a line in on the bench. If I was going to do this I would bend the line into a S shape and tack the bend against the filler tube to stabilize the line in case of vibrarions. chuck

 

Silicone and gasoline do not work together. Gasoline will eat it in a few days.
Don't ask how I know this!

 

Shouldn't be getting any gas on it. Just trying to block the fumes

 

B6TZ-9030-A (replaced 11C-9030 & 8A-9030-A) .. Stainless Steel Fuel Cap-Vented-Anti-Surge (Motorcraft FC-23) / Reproduced

Fits all 1948/69 trucks, 1970/72 light trucks w/o Evap Emission. Light Trucks: F100/350, Bronco & Econoline.

Note: All these trucks came with fuel caps from the factory that were painted the trucks specific body color. Ditto for certain Passenger Cars.

But all that was available at the parts counter was a primered fuel cap, or the stainless steel fuel cap.