shaun8484

So now that we have finally moved into a new house that I have a garage I can put my 1981 Corvette in...it smells like gas. It has not smelled like gas for the last few months in the garage until I started it up the other day and took her for a quick drive around the block. No fuel leaks that I can see and like I said, never smelled before the other day. Tank is probably only 3/4-1/2 full. I have done a search but most threads are about people swapping fuel lines and motors and other parts...this car is completely stock. The only thing I have read that may apply is that the vapor canister may have brittle hoses or it is saturated. I have not checked that yet. Any other ideas so I don't wake up in a flame engulfed house in the middle of the night?? Not sure if it matters but the car only has around 87K on it. Thanks!

MelWff

Either you have a leak which you havent found yet or the evap canister is gas soaked.

SwampeastMike

Fuel vapor is extremely hard on hoses. Definitely check the full length of the hoses. Don't forget the larger hose leading from the top front of the carburetor that vents vapor from the fuel bowl. Also there's a short length of hose running from the metal vapor line leading from the gas tank (it's attached to the frame) to the canister. There's a triangular shaped piece (metal with rubber gasket) just behind the driver wheel that removes easily (a few bolts) and gives access to the canister. If replacements are needed be sure to get hoses rated for fuel vapor as, again, it's nasty stuff that turns hoses into something resembling used (but still sticky) chewing gum.

Liquid fuel should never enter the canister and if everything is working properly it shouldn't get "gas soaked".

I believe the '81 EVAP system is very similar to the '79. The control vacuum comes from the same thermostatic vacuum switch near the thermostat that operates the EGR valve. There's a tee on the passenger side below the carb. The canister has two vacuum valves. One closes with vacuum--it's attached to the carburetor bowl vent. The other opens with vacuum--it leads to a tee in the PCV line running from the PCV valve to the base of the carburetor (this is the one that "purges" vapor from the canister at idle and cruise with the engine warm).

There's no service interval for the canister or the charcoal it contains but it probably doesn't hurt to replace both the charcoal and the foam filter on top. Use activated charcoal from an aquarium/pet store. The vendors sell the foam piece but it's easy to make your own from thin open cell foam.

DUB

You can have such a slight leak that it will not puddle up on the ground. I have repaired cars with this same issue.

You either need to try to use your nose and smell around to identify where the vapors are the strongest.

I slide under the rear bumper and smell... and if it is strong there....I have found that when I drop down the spare tire carrier and remove the plastic upper shield for it...it is stained and it is the supply or return hose going to the sending unit.

It can also be a bad vapor line that has split due to having water in it. and has froze.

The odds that your charcoal canister is filled up is highly unlikely due to....this would mean that you filled up your fuel tank all the way to the top so the vapor line was now sucking in liquid fuel and NOT vapors. So...the chances of that are unlikely. Unless you keep filling up your fuel tank AFTER the nozzle 'clicks off' to tell you it is full. A common mistake many people do who want more fuel in the fuel tank...because....there is a down side to that way of thinking.

DUB

Aerovette

How can you tell from the smell that it is 1981 gas?

j/k, couldn't resist.

Greg

hunt4cleanair

Yeah, I would say you are not at that point!
Work to isolate the source...fuel tank, engine compartment, canister or carb. As others have pointed out in detail, check the junctions where hoses connect metal lines such as the fuel tank sending unit; the canister and hoses coming to it and than route up to engine/carb/PCV connections.

So 87k miles and age suggest a good going over to ensure those hoses are fresh. They do get brittle, crack and leak fuel vapor and/or fuel.