Thread: pressure build up in fuel tank

Pressure build up is normal in warm weather. Vapour normally exits via the charcoal canister under the bonnet or the relief valve built into the cap. Check that the canister purge valve hose and wiring is connected and working, also blow air pressure through the valve in the centre of the cap. You can just use a generic Ford/Holden/Toyota screw in cap, they all fit and work the same.

Originally Posted by Eevo

in a bit stumped.
last weekend i heard the fuel tank wall move. it made a boom kinda sound. thinking it was pressure, opened the fuel tank cap and lots of pressure and vapor came out, followed by a a gurgling sound like liquid going somewhere. the tank was half full and i had been driving in the sun, so i figured pressure build up and moved on.


today i heard it again, again, i release the pressure, and the gurgling sound came again.

does this sounds like a blocked breather tube?
and how do i get at it?

Importantly was the tank half full or half empty

Originally Posted by rangieman

Importantly was the tank half full or half empty

sadly he will never know unless he drains it and measures the amount of liquid.

Mine does the exact opposite sometimes, Especially on a long run as I sometimes get a vacuum forming in the tank.
When I stop I can hear a high pitched humming coming from the filler cap and when I take the cap off I get a bit of a Woosh and the noise stops.
I will give the cap a good clean out and if that doesn't work I'll get a new one as the V8 sucks 15-16 litres of fuel every hour the cap has to let a fair bit of air back into the tank to compensate.
I imagine that this would also put additional pressure on the fuel pump and I don't think that is a good thing.

Mine has a 45L steel tank under the inlet/rear right panel,, it often pops depending on expansion or contraction,, I really dont think the system purges very often at all--- I often think a 3/32 drill through the cap would fix it,,

Originally Posted by Pedro_The_Swift

Mine has a 45L steel tank under the inlet/rear right panel,, it often pops depending on expansion or contraction,, I really dont think the system purges very often at all--- I often think a 3/32 drill through the cap would fix it,,

A good way to get atmospheric moisture inside the tank to rust it and ruin the pump.

Originally Posted by bee utey

A good way to get atmospheric moisture inside the tank to rust it and ruin the pump.

My D2a has a plastic tank

Originally Posted by trout1105

My D2a has a plastic tank

Makes little difference to the pump, it has plenty of steel components. The only benefit from a plastic tank in that situation is that's its easier to wipe out the stinking sludge that used to be fuel.