E30 fuel expansion tank

[Panici]

Hey guys,

EVAP system question.

I have a fuel expansion tank in the passenger side rear wheel well. There's also a charcoal canister under the hood.

I don't want to completely remove them, as I'll be venting a lot of gas to atmosphere.

Would it be possible to replace both of these with a (more efficient) charcoal canister from a newer car?

Cheers!

[jlevie]

No, those items serve different purposes. The expansion tank is there to capture fuel (and return it to the tank) when a full tank of cold fuel expands or the car experiences a G loading in a left hand turn with a full or nearly full tank. The charcoal canister captures vapor from the tank which is periodically sucked into the intake.

[Panici]

No, those items serve different purposes. The expansion tank is there to capture fuel (and return it to the tank) when a full tank of cold fuel expands or the car experiences a G loading in a left hand turn with a full or nearly full tank. The charcoal canister captures vapor from the tank which is periodically sucked into the intake.

Modern gas tanks don't have separate expansion tanks do they?

I thought the evap canister's purpose was to catch and return fuel vapour?

[jlevie]

Some do, some don't. As far as I know all charcoal canisters vent into the intake, usually controlled by a valve.

[Panici]

So if I always left room in the top of the gas tank, the expansion tank wouldn't be necessary?

[jlevie]

Not necessarily. On a left hand turn fuel will slosh toward the right side of the tank and can go out the breather hose that you will have to add if you delete the expansion tank/breather assembly.