Zafira (any EFi Vauxhall?) fuel tank pressures

My Zafira 1.8 fuel tank seems to be having inappropriate pressures applied
to it. At the moment it is looking like the internal pressure has been low
in that the retaining straps are not tight against the tank (the tank has
deformed). Note that opening the filler cap releases pressure (that
shouldn't be there?).

My understanding is that the tank is allowed to equalise the pressure via a
charcoal canister. This device absorbs unburnt hydrocarbons when the petrol
expands (due to heat) and allows air to flow back into the tank when it
cools. Any captured hydrocarbons are later purged into the inlet manifold
when the engine is running.

Is this understanding correct? If so, is the charcoal canister blocked to
some extent? Any other evaporative emissions failure modes (for Vauxhalls)
that don't involve fault codes?

TIA,
Mike J.

 

Talk to your dealer. I have seen this before and am pretty sure we got
an out-of-warranty contribution from Vauxhall.

It will depend on age/mileage and service history though.

Alan

 

I decided to change the charcoal filter to no affect. But:

1) the old filter was half full of water,
2) there is an unblocked connection from canister to fuel tank (bubbling
heard when blown through pipe leading to canister)
3) the proper Zafira wheelarch breather pipe is no longer available.

Item 3 was scary. I destroyed the one on the new canister to work out that a
simple 15 to 30 degree anticlockwise twist and then pull will remove it from
the old.

 

I decided to change the charcoal filter and it worked after a day or 2 (no
pressure when filler cap removed). Items of note:

1) the old filter was half full of water,
2) there is an unblocked connection from canister to fuel tank (bubbling
heard when blown through pipe leading to canister)
3) the proper Zafira wheelarch breather pipe is no longer available.

Item 3 was scary. I destroyed the one on the new canister to work out that a
simple 15 to 30 degree anticlockwise twist and then pull will remove it from
the old.