One Fuel tank is pressurized

[8474]

Rick came back and said both hold pressure if I understand his response. That would indicate no interconnect.

Unless I misunderstand him, opening either cap relieves the pressure in both tanks, therefor he does have the interconnect.

Ok, I may have mis read it....thanks

[rfrederick]

Apologies for not making this clearer.

Based on one of John's replies I had checked to see if both tanks had positive pressure and they did.
When I initially said that one tank was holding pressure that was because I opened the cap fully releasing all the pressure from both tanks; indicating the interconnect.
After John clued me in on what I was doing, I checked again by cracking one cap hearing the hiss then close it quickly, opened the other side releasing all the pressure and when I went back to the first tank there was no pressure left in it. Also I removed the wing root fairing and saw the interconnect tubes

[8474]

Thanks Rick, I misunderstood. Good to know you have the interconnect with a BOTH selector. But even with that interconnect those A model caps are incorrect, thats why you have positive pressure when opening either cap. Your issue will go away when you get those new vented caps from ACS.

[dtpilot]

I just bought the Cessna 120 I owned 25 years ago. The plane has two of the "new" vented caps. The first time fueling (after sitting in a hot hanger), I noticed the tanks were pressurized. With the new caps, there is no way for the expanded fuel/air in the tanks to vent (no other tank vent in the fuel system). Would there be any issue if I simply removed the rubber valve from the caps? This way they will vent in both directions, similar to the original (two-hole) cap. Thanks, Dave

[2066]

I just bought the Cessna 120 I owned 25 years ago. The plane has two of the "new" vented caps. The first time fueling (after sitting in a hot hanger), I noticed the tanks were pressurized. With the new caps, there is no way for the expanded fuel/air in the tanks to vent (no other tank vent in the fuel system). Would there be any issue if I simply removed the rubber valve from the caps? This way they will vent in both directions, similar to the original (two-hole) cap. Thanks, Dave

RE an "issue", IDK. Will it work "OK" -- probably. Obviously it's important that they vent both ways. The safest will be to obtain the OEM caps -- best I recall Columbia Airmotive may have some(?) and, of course, there's always Ebay where they show up from time to time.

[6298]

I had that issue years ago. Removed the rubber, so they vent both ways. Worked fine for years now. You can buy similar caps of the original on Spruce. you will need to drill the two holes for venting, but they are pretty inexpensive.

[dtpilot]

Thanks for the responses gentlemen. Sounds like removing the rubber valve to make the caps vent both ways is the way to go.