Vacuum in the fuel tank

[rion]

guys, what is the best way to relieve fuel tank pressure? the pressure is great that the cap cannot be remove if you close the cap tight. even when not tight, when I remove the fuel tank breather pipe, I will hear vacuum.

Both ends of the breather hose seems NOT blocked. because when I tried to blow air to it. I hear air passing either ways in or out.

I already switch the cap from another same ride, but same problem. the other ride seems working fine with the suspected cap.

any solutions?

I read that one solution is to drill hole in the cap. but is it really safe? a fuel singaw from the fuel cap hole seems dangerous.

[fourtheboys96]

i think your talking about fuel pressure and not vacuum. if that is the case, you don't need to worry because its normal. gasoline is a volatile substance and tends to evaporate resulting to build up of pressure inside the tank.

if i am not mistaken, this pressure helps deliver fuel to the engine.

[rion]

it's vacuum, its giving me hard time opening the fuel cap once closed shut.

[bambino]

what's the year model you have?

most OBDII SYSTEMS are equipped with computerized EVAP SYSTEMS and that can only be corrected by using a scanner to properly diagnose it with the aid of smoke machine.

[rion]

it's old 95'. and it doesn't have OBDII slot unfortunately.

[v6dreamer]

The breather system is probably plugged. There is a tube from the gas tank to the evap emission canister to control the emmission of VOC (fuel fumes), the canister absorbs the fumes, hydrocarbon and sends liquid gas back to the tank. Check for any plug lines. It also vents excess pressure with greatly reduced VOCs. Somewhere along the line, some thing is blocked.

Warning - the old canister is highly flammable.....so be very careful.