Fuel tank expansion noise

[nasz]

Anyone else get this!

Sort of boom noise every so often as the tank contents rapidly diminish!

[wolosp]

I was tempted to recite Baldrick's poem "The German Guns", but thought better of it!

Try releasing the filler cap a bit to prevent vacuum building up in the tank. I leave the cap a bit loose on mine.

[mgman50]

Yes I get the boom too, normally just after starting the car and reversing. Last time the poor tyre fitter when moving the car thought he had backed into something, the look of suprise on his face made me chukkle. Got used to it now, but new passengers ask whats happened. Have to live with it just like the tikking spedo.
jack

[M@H]

Its because your carbon cannister is not working as well as it should. Basically there is a fuel tank vent that vents to atmosphere at the front of the car, but the fumes go through a carbon cannister first which is located in the front wing.

If the cannister is not venting (ie blocked), as the fuel tank empties you get a partial vacuum forming in the tank. The clanking noise is the tank collapsing on itself a bit, not expanding. This is a common "characteristic" on older cars.

Cheers,
Matt.

PS, you don't have to live with it, you can replace the cannister.

>> Edited by M@H on Monday 15th November 15:22

[shnozz]

M@H said:

Its because your carbon cannister is not working as well as it should. Basically there is a fuel tank vent that vents to atmosphere at the front of the car, but the fumes go through a carbon cannister first which is located in the front wing. If the cannister is not venting (ie blocked), as the fuel tank empties you get a partial vacuum forming in the tank. The clanking noise is the tank collapsing on itself a bit, not expanding. This is a common "characteristic" on older cars. Cheers, Matt. PS, you don't have to live with it, you can replace the cannister. >> Edited by M@H on Monday 15th November 15:22

spot on. take out the cannister, give it a thump and bingo.

[nasz]

oo-er where's ma cannister!

Will check out the Heath guide tonight! Thanks all!

[shnozz]

front passenger wing

[M@H]

shnozz said:

front passenger wing

indeed.. behind a small access panel.