Why does my petrol tank "thunk" ?

[ec1 eex]

For the sake of doubt, this is not a spoof of the "why does my steering clunk?" thread.

I've had my tuscan for 5 years now, and only in the last couple of days I've heard my petrol tank "thunk" a few times. It's as though there is a light dent in it which keeps popping in & out. I'd say that the fuel pump is changing the pressure within the tank, but it can pop from one state to the other after going over a bump.

Any ideas? Should I be concerned? Does anyone else get the "thunk" ?

Thanks

Phil

[xxlmuscles]

Mine "thunks" sometimes when I take off the fuel cap, as if its vacumed. Only does it every now and then though.

[Alpinestars]

Mine thunks as well. No idea why.

[bsod]

True, Mine thunks as well, only when turning the ignition on at startup, I think your right, its pressure change in the tank as the pump starts up. Must admit there is quite a suction effect when I take the cap off.

Thanks for asking the question, as I felt too silly to ask first.

[ehasler]

I've noticed mine doing it too sometimes - usually when the tank is low on fuel.

[ec1 eex]

I'd hadn't noticed this before. I guess we should add this to the long list of "they all do that sir"

[boardinscotland]

ec1 eex said:

I'd hadn't noticed this before. I guess we should add this to the long list of "they all do that sir"

mine does

Edited by boardinscotland on Sunday 4th January 01:22

[davido140]

Mine doesnt!! Does that mean its broken?

[BGB autosport]

davido140 said:

Mine doesnt!! Does that mean its broken?

Mine doesnt either so yes it probablly does, as most other things are!

[Hickling]

You'll all probably find that one of the two pipes that go into the fuel tank is blocked. one of these is a venting pipe that equalizes the air pressure in the fuel tank, & over time it will cause your fuel tank to split.

[ec1 eex]

Hickling said:

You'll all probably find that one of the two pipes that go into the fuel tank is blocked. one of these is a venting pipe that equalizes the air pressure in the fuel tank, & over time it will cause your fuel tank to split.

So where is the venting pipe to be found ?

[T66ORA]

Had this problem on the Tamora, worth reading this thread.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...