Gas Leak from Filler Vent Hose

Just filled up the CJ last night and found a puddle of gas behind the right rear tire this morning. Traced it to a leak coming from the filler vent hose just before the clamp attaching it to the tank, likely due to dry rot. I know I can order a new one from a few places, but was wondering what to do in the meantime. Should I just take it out for a spin until I've drained the tank down a gallon or two, keeping it half full until the replacement comes in?

 

I've used electrical tape to successfully Band-Aid a leaking vent hose. The gas made it a little gooier and it sealed for a week till I got it fixed.

 

Thanks.

 

Update . . . I started the engine and the leak immediately went away (presumably because the fuel was being pumped/pulled away from the vent hose?) and let it idle for about 15-20 minutes. The leak did not return when I turned the engine off. Is this strictly a function of the fuel level in the tank or do I need to worry about vacuum issues? Regardless, am I right in thinking that replacing the vent tube will likely solve the problem?

 

I would suspect it's more about vapor pressure that builds up in the tank when the engine is off. These are supposed to be sealed tanks, and the gas cap does not normally have a vent. Ideally the pressure is supposed to exit through the liquid check valve then to the charcoal canister.

 

Thanks, Tim. My gas cap is stamped "VENTED" and "ANTI SURGE" on the inside (it takes a key that reads "GAS" . . . might be original???). I suppose the cracked filler vent hose is the path of least resistance for gas to escape from vapor pressure build up? My CJ has the liquid check valve and charcoal canister. So, replacing the filler vent hose should take care of the leak, seal the tank, and put the LCV into play, yes?

 

The vapor recovery will do nothing if you have a vented cap. The vent defeats it.

All '74 CJs had vapor recovery, so the vented cap cannot be original.

Take care of the leak? Well, I guess so... if the vent hose leaks, you have to replace it.

 

Got it. So I will replace the vent hose and look for a non-vented gas cap. Thanks for all the help.

 

Hey, I hope I didn't seem too brusque. I think it's going to leak some from slosh, even if the fuel level isn't that high.

This is the glug-glug hose, right? Fortunately these are available from MTS if not other places - http://www.mtscompany.com/jeep.htm CJVH-3

 

Not too brusque at all. This is all educational for me. I'd like to make sure I'm running the right set up for my stock 74.

It is the hose you identified from MTS. Looks like I can buy that part through several retailers like Morris 4x4 and 4 Wheel Parts. I'll look for a non-vented cap from one of them too.

 

the local napa can get the correct cap for less than a specialty place...most of the hard parts(brakes exhaust engine parts etc ) ive found to be a lot cheaper there than online i think its like a boat or snowmobile,they will jack the prices up cause its a luxury thing...

 

Too late. I already ordered online through 4 Wheel Parts (no shipping costs with in store pick and there is one on my way to work). But you're right, it would have been (slightly) cheaper to go through NAPA. I would have saved $.06 on this particular purchase. Thanks for the suggestion; there's a NAPA store on the way to work as well and I'll be sure to check with them on future purchases.

 

i forget i get a beeg discount..... seriously brakes and such are cheaper, wish i had a four wheel parts near here, i got trees and rocks instead gotta drive 30 min to get a stop light i guess ill take it

 

Update . . . I replaced the filler vent hose and purchased a non-vented gas cap and all seems to be working just fine. One last question . . . assuming my vapor recovery system is working correctly (and I have no reason to believe it isn't . . . all the parts seem to be in place and in good shape), is there an advantage to using a vented cap versus a non-vented cap?

 

If you use a vented cap, it defeats the purpose of the vapor recovery system. A non-vented cap will force all vapors through the recovery system.

 

I think the question is - do you want your vapor recovery to work? It's just dead weight when you fit a vented cap.

There's no major downside to the vapor recovery system. Maintenance is extremely minor, the parts can be expensive and elusive (but not an issue if you have them all), and some people don't like all those ugly extra hoses. When it works, it's completely passive and has no effect on performance. The upside is considerable IMO. Aside from cleaning up emissions, your car will never stink of gas, the sealed cap does not leak (no drip-drip on steep hills or side-hills), and you are recovering and burning a small amount of fuel that would otherwise evaporate.

Up to you.

 

Thank you. That's the info I was looking for.