Vented gas cap needed - Stant?

[AdamH]

I need to pick up a vented gas cap but cannot remember what fits. I had one on my CJ7 that I think was a Stant but can't be sure. Does anyone know make / model number of what would fit?

Thanks,

 

[bigwalton]

I couldn't find one for Mater, ended up taking the non-vented cap, unscrewing the "handle", drilled a small hole in the middle of the cap, reinstalled handle.

 

[AdamH]

I want to say the one on my CJ7 was a Stant and was made for a Chevy - maybe I will just go grab one and try it if no one has any info.

 

[mysunnshine]

Stock and replacement fuel caps are vented already. There is a check valve in the center to allow air to enter the tank but not allow fuel vapor out. If you want an open vent cap, then get a pick and root around in the hole in the center of the cap and pull out the small hair spring in there.

 

[flashover604]

Funny story regarding vented caps... I had a 1923 Ford T-Bucket with a 289 Hi-Po. I checked the oil every time I drove it. I noticed I was getting fuel in the oil. I replaced the fuel pump. Replaced the regulator. Rebuilt the carburetors. What it ended up being was the fuel cap. The aluminum fuel tank would cool down, create a vacuum pulling air IN through the check valve. When it would heat up and expand the air inside would create pressure that couldn't get back OUT through the check valve so it would push fuel through the carbs into the crankcase. I pulled the spring out of the cap and never had another problem with fuel in the oil.

 

[mysunnshine]

Fuel injection does the same thing. The tank was not designed to handle a full return system and the vapors that are associated with it. Then complicate it with a return that dumps into the top of the tank and not INTO the fuel itself. Then the fuel splash causes vapors too. Then add in excessive ambient heat, E10 fuel, and heavy loads then the 1/4" vapor line isn't nearly enough to purge without causing tank pressure.

 

[Dave The Sparky]

Crown part No J0934197 is the vented export version, i have one on its way so cant tell you if its any good yet!!!

 

[1980cj7]

I have been getting a huge whoosh of pressurized air out of the gas tank on my cj8. Can excess pressure cause problems? I'm running a CSB with tbi.
Thanks
John

 

[AdamH]

Crown part No J0934197 is the vented export version, i have one on its way so cant tell you if its any good yet!!!

On a whim I ordered this one just to see if it would fit. It does not fit an '81 US version FYI.... I plan to pull the spring like mysunshine until I find one that fits. The original one I has a bad finish on it that I can't get to shine so I do want to replace at some point.

 

[mysunnshine]

Just a note here....If you wheel with the newly vented cap(without the spring mod), with a full tank of fuel and inclines, it will purge fuel right out the cap.......

 

[AdamH]

Just a note here....If you wheel with the newly vented cap(without the spring mod), with a full tank of fuel and inclines, it will purge fuel right out the cap.......

I had that problem on my CJ7 just city driving. Hopefully I won't have that problem with the 8. It won't be on the trails.