Strong gas smell when engine is running...
 

Recently I’ve noticed that if my car sits for a few weeks between drives that there is a very strong gas smell once first started and it’s running for a while. Don’t see any fuel leaks anywhere and doesn’t smell like gas when off and parked in the garage. Pretty sure it’s coming from the exhaust. Seems to go away after 30 mins or so of driving (or I just can’t tell the difference by then). Hasn’t always done this so think something may be going kaput or maybe I’m just driving it less frequently than I used to. Haven’t done any work on it lately that may have caused it.

No CAT on car, Steve Wong chip, seems to run great like always, top end rebuild a couple years ago, O2 sensor still connected…

Any thoughts what might cause this? Can injectors “leak down” while just sitting for a week or too and flood the combustion chamber? Like I said, starts fine, idles and runs like normal, just smells like a lawnmower now.

When was the last time the high pressure fuel lines on the engine were changed? They are subject to aging, cracking and bursting.

In the trunk, Front, is a small plastic bottle that is attached to your fuel system. Mine was cracked and the smell of fuel was very strong.

The pressure lines were changed during the top end work. I've checked all over and don't see or smell any leaks while sitting in the garage... only when the engine is running. That's what got me wondering if an injector could be causing it.

I think you're smelling unburned hydrocarbons in the exhaust because you don't have a catalytic converter. You're smelling it more at startup because the DME is making it run rich while it's cold. Once warmed up, the mixture is leaned out.
When I was growing up in the 50's and 60's, all cars stunk. No cats. Put the cat back on & the smell will go away. If it's a recent phenomenon, have you changed gasolines? Maybe you're just noticing it more lately when you overlooked it before.

you can use a CO meter to sniff out gas fumes

Just to echo a couple of posts above - I put the cat back on my car (came to me with headers, no cat) Went from the old car gas smell to very little smell.

My rub on this is he would smell it when just sitting in the garage. Failing gas caps are known for stinking up the cabin plenty as well when at rest.

The charcoal filter is a passive device soaking up fumes when the engine is off. When the engine runs there should be a pressurized flow from the engine to purge the fumes from the filter. If the return line is plugged or there is a leak from cracks, then there definitely could be a strong smell after starting the engine that is reduced over a period of time.

I know on the mid-year and very early SC's there was a pressure feed line from the fan shroud to the charcoal canister. My 81 canister has the port for this pressure line but the port on the shroud was discontinued so it's moot. I suspect it is a one way port on the canister.

On my 81 it's all vacuum. One tiny hose goes all the way to the big expansion tank and little white expansion tank. The path is interspersed with metal tubes that connect to the hose near the transmission and flow to the front as well as through the fender to the hanging expansion tank. Fumes travel through the little line from front to back into the canister in the engine compartment and are sucked into the top side of the airbox via a fatter hose that wraps around to the driver's side and plugs in just under the air filter BUT not into metered CIS air.

All of that said, I don't know shiet about the 3.2 except the canister is in the right rear wheel well. There may be pressure. I am not aware of this and if pressure forces the fumes into the engine, your thoughts sound reasonable. I am pretty sure pressure would not scavenge the fumes from the front.