gas smell

[Kelly Coleman]

my 70 300 has been very gassy smelling for awhile. Thought it was from too much under hood heat so I would open hood after I parked it to let heat out. Not the problem. Found 2 rubber caps on gas tank that were rotten, replaced them, now no smell from under hood. still smell gas from under trunk, replaced gas cap, no change. checked vent tubes, then one that dumps right above rearend was plugged, fixed that. blew air though the other and it was clear. blew air into tank and they were clear. still smell gas when I park car. take gas cap off and there is some pressure in tank?????????????????

 

[1970FuryConv]

my 70 300 has been very gassy smelling for awhile. Thought it was from too much under hood heat so I would open hood after I parked it to let heat out. Not the problem. Found 2 rubber caps on gas tank that were rotten, replaced them, now no smell from under hood. still smell gas from under trunk, replaced gas cap, no change. checked vent tubes, then one that dumps right above rearend was plugged, fixed that. blew air though the other and it was clear. blew air into tank and they were clear. still smell gas when I park car. take gas cap off and there is some pressure in tank?????????????????

Any chance of rust thru on top of the tank?
I had that happen on a 1970 Sport Fury.

 

[Kelly Coleman]

New tank 5 years ago

 

[Boydsdodge]

Since it is a new tank, maybe the after market sending unit seal or filler tube grommet is failing. I had an aftermarket filler tube leak within a year. Bought new seal from Chrysler dealer and no problem.
Just my thought.

 

[fury fan]

You are using a vented cap, correct? New cap you tried is vented?
Any difference in fumes when tank is full, empty, etc?

 

[Kelly Coleman]

Was supposed to be a direct replacement for original does it mostly 1/2 tank or more

 

[thrashingcows]

I had the same thing on my wagon and put a new filler neck seal on it...nope still leaking gas fumes, put a new gas cap on it...nope still leaking fumes. Then one day I installed the gas cap upside down by accident and guess what...no more fumes! Not sure why it seals one way and not the other but this is just the way it is on the wagon...

 

[fury fan]

Was supposed to be a direct replacement for original does it mostly 1/2 tank or more

And presumably more in the summertime when it is hot?

I would crawl underneath it and see if there is some fuel seeping/wicking out somewhere.
See if the tank is bulging, too. I've never experienced it, but I've heard that can happen.

 

[Mudeblue]

New tank 5 years ago

Did you put in a new gas pad when you you put in the new tank. Surprisingly often overlooked.

 

[Kelly Coleman]

Gas pad??

 

[MarPar]

Sorry, couldn't resist

 

[Sir Dodge alot]

Had a gassy smell in the trunk compartment AND the cabin compartment.

As the other members have chimed in, a gas cap also.

Replaced the fuel sender gasket, smell is minimized, few days of driving after. The fuel pump failed on me.

Replaced the fuel pump. No more gassy smell in the cabin compartment!

Trunk gassy smell may be a rich A/F mix AND a hole in your exhaust system AND a rust/pinhole in your trunk allowing the gassy exhaust fumes to vent up and into the trunk.

If it may be an exhaust leak, look for black sooty carbon near the muffler also.

 

[Big_John]

Whenever there's a gas smell in my car, it's usually something like Mexican food that caused it.

 

[Sir Dodge alot]

Whenever there's a gas smell in my car, it's usually something like Mexican food that caused it.

Like Taco Tuesday eh? LOL

 

[3175375]

Whenever there's a gas smell in my car, it's usually something like Mexican food that caused it.

Or s-l-o-wwwww cooked bbq ribs

 

[1970FuryConv]

Gas pad??

Hi Kelly,
Fuel Tank Pad
Example for your car from Vans Auto
Fuel Tank Pad Mopar 1965 - 1973 C-Body
Hope it helps! Ben

 

[Kelly Coleman]

with new cap on and both vent lines open I still get pressure in the tank???

 

[Gerald Morris]

with new cap on and both vent lines open I still get pressure in the tank???

You'll sure as **** get SOME pressure in HOT summer weather. even with the vent tubes open. Gasoline is VOLATILE AS ALL HELL, and MODERN "gasoline" is based on heptane and hexane more than the older stuff, which was heptane and OCTANE. The older fuel had other stabilizing additions like white lead (tetraethyl lead) which also made it heavier, and less apt to ping or knock. Consequently, the stuff behaved better in hot weather, aside from poisoning kittens and children et cetera...

The tank pad should insulate your tank a little from incident heat from the car. I often have to siphon off a couple gallons from Gertrude's tank after filling to keep her from pissing valuable, flammable petrol from the vents during summer, and am strongly considering a charcoal canister to catch that ****, though I don't plan to plumb it into the fuel intake up at the carb, as my '83 Dodge has it.

You very well may have some crap floating in your tank, partly plugging those vent lines too. My tank is just over 6 yrs old, and also a 2 vent sort, so I relate to your blues with this. Its hard to score a GOOD U.S. made OEM gas cap also I've found. Bad ones abound, but GOOD ones?! I have exactly ONE to date..... though the locking cheapo plastic thing from VatoZone did alright for the year I used it.

Purge your tank, then see after a good check and cleaning what it does.

 

[1970FuryConv]

with new cap on and both vent lines open I still get pressure in the tank???

Hi Kelly,
Is the pressure detected when you remove the gas cap? If not, how?
Are the vent lines both open, like you can blow air through with an air hose? Carburetor cleaner might help full/partial clogs
Can a coat hanger be pushed into the vent ports and not come out with any debris? Carburetor cleaner will also help. Gunk is a good brand.

The vent lines are primarily responsible for keeping pressure in tank the same as pressure outside tank.
You can buy a vented gas cap, but from what I have read, that will not compensate for malfunctioning vent lines.

Best of luck, Ben

 

[Kelly Coleman]

blew air though vent lines and into tank. there are two other holes coming out of tank that are capped. I assumed they were maybe for fuel return if needed??? Its a quanta tank. Were the oe gas caps vented??? Drove it yesterday, sat in the shade when I parked for 30 min, got home 1/4 tank gone and still had pressure in tank when I unscrewed the cap.