Road Runner vented fuel cap

[Richard Cranium]

I'm looking for a vented fuel cap for my 69 Road Runner. While scanning fleabay this morning, the only vented caps I can find are for a 1970. Does anyone know if the caps are interchangeable between 69 & 70?

http://www.ebay.com/itm/1970-Plymou...ash=item540ea72671:g:isoAAOSwsN9XAXbE&vxp=mtr

http://www.ebay.com/itm/Mopar-Fuel-...ash=item4b021b9fcd:g:FFoAAOxygj5SkXRB&vxp=mtr

 

[Beekeeper]

I thought the cap on the 69 roadrunner was a non vented cap?

 

[Torkmnstr]

Yea mine is non vented for 69. Got it from year one many a years ago

 

[1969 Hemi RTs]

1969's used a non vented gas cap. the tank has a venting system so no need for a vented cap.

 

[Beekeeper]

With the location of the filler neck a vented cap would lose gas when the the tank was half full
or full or on hard acceleration.

 

[bee71]

Vented caps started in 72 I believe as the government wanted more restrictions on vapor venting into the atmosphere.

 

[440+6]

Don't know about 69 but in 70 the vented are for the California tanks and non vented are for the regular ones, anyway the caps won't interchange.
The vented cap won't fit on a regular tank without modifying something. I tried one a buddy had for a road runner.

 

[wagonman]

Rick Eherenberg has them both ways on his E-bay site.

 

[Dennis H]

69. Non vented.

 

[Richard Cranium]

The problem with the Road Runner is when the tank is full, the fuel expands and it drips out the vent tube. I was thinking that a vented cap might solve this problem. This isn't the only Road Runner that I've had with this same issue and it seems that this is a flaw in the design. Other than keeping the tank 3/4 full, is there any other solution?

 

[1969CoronetR/T]

My R/T does the same thing especially when it is hot outside. I only put five gallons in it at a time. It gets about five miles to the gallon so I have to plan my trips around gas stations. This reminds me of my seventy year old father who has to plan trips around bathrooms.

 

[440+6]

The problem with the Road Runner is when the tank is full, the fuel expands and it drips out the vent tube. I was thinking that a vented cap might solve this problem. This isn't the only Road Runner that I've had with this same issue and it seems that this is a flaw in the design. Other than keeping the tank 3/4 full, is there any other solution?

Well the vented cap let's air into the tank easily, but it takes a fair amount of pressure to let air escape. It would probably come out the tube first anyway unless you cap the vents.
I've been thinking about all this because mine will spit a bit out the short vent tube when full also, but I'm not sure what the best solution is.

 

[moparedtn]

For what it's worth, I put a vented one on my '68 because of some misguided sense of needing to do so when I removed all the vapor return lines from the car.
I can say I haven't witnessed any fuel leakage at the filler neck yet.
I also am curious about the "right" answer for this.

 

[wagonman]

Do you have the tank with 2 vent nipples? When I replaced my tank it had just the 1 line that is in the trunk but the short one was missing. I just bent up a shorty and put some generous bends and lenghtened it about 6 inches. No issues with a non vented cap and a full tank. Course it rarely get over 90 here. I sure dont like the idea of $10 a gallon race fuel peeing on the ground let alone the safety issue. Mine is a 68.

 

[Dennis H]

Does the existing vent routing look like this?

 

[moparedtn]

Do you have the tank with 2 vent nipples? When I replaced my tank it had just the 1 line that is in the trunk but the short one was missing. I just bent up a shorty and put some generous bends and lenghtened it about 6 inches. No issues with a non vented cap and a full tank. Course it rarely get over 90 here. I sure dont like the idea of $10 a gallon race fuel peeing on the ground let alone the safety issue. Mine is a 68.

If that question was for me, yes, mine has the two vents in place.
I probably should replace the cap with a non-vented, I suppose...

 

[Dennis H]

Finally got mine atraightened out. When to a hot place this weekend. Filled tank to brim, parked on an incline. No fumes, no purging. Fuel gauge works. Tried so many things to get it this way, can't remember how to explain it except to route the vent high inside the trunk. Got a 70 tank in my 69 so it has an extra vent that is plugged. That because of asshole MoparEd (Central Valley - not tn, different Ed).

 

[Richard Cranium]

Does the existing vent routing look like this? View attachment 345687

Yes it does and it's the original tank.

 

[bigmanjbmopar]

I solved mine by finding out the two vent lines in the 80's-90's replacement tank that was put in has the vent lines backwards and I switched those and all that did was switch the full tank over flow from front end pointing up hill spill out to front end pointing downhill spill out. Found out the real issue is today's fuel expands at a faster rate when hot then it did 40 years ago so to fix this I took my non vented cap and turned it into a vented cap by carefully drilling two 1/8" holes in the outside of the cap with the vented words, careful not to drill through the rubber gasket on the other side. I also added a fuel filter small inline to the top vent line, the one that curls up at the top of the axel. Ever since then I have not had any leaks or any ful smells or at least with a full tank on a hot day pulling into the garage very little smell if any.

Side note I have tried several different brands of vented caps from all brands and all years just to find out none of them worked at all either didn't fit or leaked badly. Hope this helps.

 

[moparedtn]

Finally got mine atraightened out. When to a hot place this weekend. Filled tank to brim, parked on an incline. No fumes, no purging. Fuel gauge works. Tried so many things to get it this way, can't remember how to explain it except to route the vent high inside the trunk. Got a 70 tank in my 69 so it has an extra vent that is plugged. That because of asshole MoparEd (Central Valley - not tn, different Ed).

Appreciate that.
Glad yours worked out. Turns out, mine is now sorted too, except for the accuracy of the gauge - and it isn't worth my dropping the tank again to adjust the sending unit. I can live with it.