I've searched the forums and found both answers, so I am asking this question directly: Are the gas caps on an 89 4Runner DLX 22RE supposed to be vented or nonvented?

I have fuel leaking from the charcoal canister, only when the pressure is high in the gas tank. Canister is good, gas gets in to it, so I assume the line from the tank is good. Just seems like too much pressure. Additionally, is there a check valve that stops vapor from re-entering the gas tank from the canister? How would I check this line for certain?

Thanks

 

I DON'T KNOW the answer for an '89.

Having made that disclaimer: a vented gas cap is generally supposed to allow air in, but nothing out. If it let anything out, it would be letting vapors out, and that defeats the purpose of the canister.

The line from the tank to the canister (at least on my '94) has no check valve; vapors go into the canister when not running, and if the fuel tank gets cold enough it can suck the vapors out of the canister.

So why are you leaking fuel? My first guess (remember: guess) is that the fuel is correctly condensing in the canister, but when the engine is running it is NOT sucking those vapors into the intake (as it is supposed to). So you just keep accumulating vapors until you get a leak. I'd look in the FSM for the procedure to check the canister; one of those procedures checks the vacuum from the engine when warm and above idle. It's that vacuum that sucks the vapors out, which doesn't seem to be happening for you.