Gas tank vacuum

[bonsaiwino]

I've noticed that my '79 Spider has a noticeable suction noise each time I remove the gas cap to fill the tank. What should I look for to remedy this? Thanks, Don

[baltobernie]

Your problem lies in the evaporative emission control system. This system prevents raw fuel vapor from escaping to the atmosphere. You may have a clogged charcoal canister, defective valve, collapsed lines, or other issues. A properly functioning system should have a slight pressure (not vacuum) when the cap is released.

First step is to tell us if your car is carburetetor or FI. Then Search this forum on this topic.

This should be repaired before you damage your fuel pump or the gas tank itself.

[bonsaiwino]

It's carbureted. I was going to attempt to restore the vapor canister. The line from the filler to the tank is clear. For now, is it ok to not tighten down the filler cap all the way down? Of how about venting the lines down toward the raid without using the canister? Really appreciate the advice.

[mscafide]

I drilled a tiny hole in my cap and created a vented cap like the old days.

MIke

[bonsaiwino]

Here's what I meant to say above: how about venting the lines down toward the road without using the canister? Really appreciate the advice.

[spidernut]

Are all the vapor lines clear going to this? http://www.autoricambi.us/product/FU0-0 ... por-Union/