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Gas Tank Overpressure?

Shogun

NAXJA Forum User
Installed new "long-range" fuel tank (32 gal). Have been noticing that upon removal of the filler cap there is alot of air pressure, way more than ever before. Sometimes I hear the tank pop out.

The tank has one of the two OEM vents installed. I dont know if these are one-way vents or two-way. I suspect it is not operating in the outgoing direction, or the line is clogged.

Due to the fun involved in removing the tank to check/replace the valve I will just test the line. But pending further info, any problem with leaving the cap loose? (non-OBD2)
 
You sure it's positive, and not negative, pressure?

I could see some positive pressure from pumping cold gas out of the ground, then warming it in your tank.

But I'd think an unvented tank would create much more negative pressure as you suck 20 (or 32) gallons of gas out of it...

It'd still hiss when opened, and could even "pop" if the tank deformed...

Just a thought...

Robert
 
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