over pressured gas tank

[4404spdcharger]

It was a hot day in Colorado, over 90F.  I stopped to filler up, got a "whoosh" when I opened the gas cap. Strange.   Filled the tank, then drove 50 miles home, going from 7000 ft to 9000ft.  The car wreaked of gasoline.  I opened the gas cap and got sprayed with gasoline!  I bled off the pressure but the air coming out of the tank was really hot.  I assume the following happened: The heat from the engine vaporized some of the gas and the separator sent it back to the tank to condense as it's designed to do.  But the heat and altitude expanded the gasoline and left little room for expansion so it pressurized the tank, a lot.  My question is: the Service manual talks about a vent coming out of the tank near the fuel sender.  I can't find it.  Does a 440 RT have that vent?

[Budnicks]

On 68's There is a vent tube on the tank going next to the filler tube at the tank, it runs up to near the top of the filler tube, you need a gas cap that will allow it to vent also, possibly a restriction, collapsed rubber hose or a clog in the vent line or wrong non vented cap... I know later yaers had multiple vents from the fuel tank combined rubber & steel lines with small orifices... Just spitballing...

[tan top]

On 68's There is a vent tube on the tank going next to the filler tube at the tank, it runs up to near the top of the filler tube, you need a gas cap that will allow it to vent also, possibly a restriction, collapsed rubber hose or a clog in the vent line or wrong non vented cap... I know later yaers had multiple vents from the fuel tank combined rubber & steel lines with small orifices... Just spitballing...

69s had the same set up

[Budnicks]

I see in the "Charger Super Bee & Road Runner restoration guide"  (by Paul A. Herd, Motorbooks Workshop) some cars with E.C.S. had a multiple vent tubes on the opposite side of the tank from the filler tube that vented into a larger tube running into the body.... 1970 cars sold in California have the E.S.C. (vented fuel vapor regulated smog requirements) was mandatory, it was optional in other states....

[4404spdcharger]

There is a vent that comes up the side of the filler tube and enters the filler tube just below the cap.  However, the gas cap (like a rad cap) has a seal surface that seals the tank when you snap the gas cover down.  I guess I'll keep an eye on it in the future and be aware when it's hot.  And maybe not fill the tank so full when it's over 90F.

[Budnicks]

Even at those temps it shouldn't pressurize like that, even heat expansion they need to vent, have you had any vapor lock problems in the past? sometime s that's a sign of improper venting it can be very dangerous, imagine a static electricity charge & opening the cap, puff,  you will become a human torch..  :flame:not cool, no pun...

[4404spdcharger]

It's never vapor locked on me before.  So it appears there's only the vent on the filler tube but it's not vented to the atmosphere.  Not much of a vent is it?  I agree, gasoline vapors are highly explosive. 

[Charger-Bodie]

It's never vapor locked on me before.  So it appears there's only the vent on the filler tube but it's not vented to the atmosphere.  Not much of a vent is it?  I agree, gasoline vapors are highly explosive. 

That small tube runs thru the floor and out into the air via the inside of the frame rail.

[elacruze]

I have the same problem, simple enough your vent tube is blocked. It's easy enough to pull it out from the trunk and clear it. Probably a bug made a nest in it.

[4404spdcharger]

After talking to Troy Hawkes, knower of all things about Chargers, the vent tube on the filler seems to be the culprit.  I (erroneously) thought for some strange reason it went into the tank.  It doesn't and as 1Hot Daytona has confirmed, it vents to the right frame rail.  Thanks everyone for the help.  Beer's are on me next time you're in Fort Collins.

[4404spdcharger]

I mean left frame rail.

[Nacho-RT74]

usually the vented tanks are as far I know to let the air to get in for a while gas tank is getting emptied