In the cab gas tank problem!
 

Drove the truck to work for the first time (6/1/2016) and showed the truck to a few coworkers at noon and all was fine. I noticed the cap was not fully seated so I pulled the rubber up on the gas cap and gave it a good turn. At 6pm on a hot day I go out to the truck and the smell of was so strong! Open all the windows and drove home higher then a kite. Pulled the seat forward that night to find the floor board with a thin layer of gas on both sides and the 3M spray glue was now jelly and the insulation wasn't attached to the floor anymore. I cleaned off gas and glue off the floor with soap and water and it still smells strong. Drove it to work today (6/2/2016) and released the gas cap and heard it suck and the gas tank pop/oil can so much for the cap venting!? I believe the high out side temps, almost full tank and the gas cap tightly in place pushed the gas passed the float fuel level sending unit rubber gasket. I'm attaching photos. BTW I did clean out the tank, red coat the tank and replaced the float a month ago. Any thoughts on how to fix this? Wrong cap? Bad cap?

Thanks

Re: In the cab gas tank problem!
 

just a guess, but are you sure that is a vented cap and not a 71/72 style cap? The earlier trucks need a vented cap and the later trucks vent through a hose on the tank. May not have been noticeable until it got hot outside.

Re: In the cab gas tank problem!
 

It looks like the same cap that was on the truck... I watched the clerk at Auto Zone pull the data up... it wouldn't be the first time that the data base was wrong... Thanks for the reply!

Re: In the cab gas tank problem!
 

Manestruckparts.com that doesn't even look close to being the right cap .

Re: In the cab gas tank problem!
 

Thanks for the info!

Re: In the cab gas tank problem!
 

Since a 70 does not have a return vent line running to a charcoal canister I believe it's a cap issue. I had a similar situation on my old 72. Someone had removed the charcoal canister and plugged the vent line. Everytime I would remove the gas cap there would be a lot of pressure built up plus an awful smell in my cap also.

Ray

Re: In the cab gas tank problem!
 

Thanks for the info Ray! I purchase and new but old school gas cap and no pressure build up so far. One note all the locking gas looked very similar dimensionally as the one I had issues so I'm stayed clear from all of those types.

Re: In the cab gas tank problem!
 

Your original cap in the picture is exactly the one I have on mine, a 72, although I have a vent line coming from the tank. I always thought my cap was vented but your post has taught me something new!