1995 Blazer - 4.3 Vortec V6 CMFI (vin W w/ PCM)
230,000 miles
There are no trouble codes. This is a OBD-I or 1.5 system from a GM transitional year (I have the OBD-II style connector).
I have issues that are possibly related to the Evaporator Canister Purge system...
- Occasionally, I get "dieseling" (run-on) after shutting off the truck.
- I occasionally smell a slight amount of gasoline fumes when driving with the windows down.
- After fixing a lot of other things, I still occasionally have some slight lack-of-power issues.
The gas smell seems to be coming from the rear of the truck. When I remove the tank vent from the canister, a little gas drips out. I know that's not right. Visually, I see no leaks from any of the lines or the canister.
The GM service manual also has a page for "dieseling" in the drivability section. It points to the Evaporator Purge system.
So what causes gasoline to get into the vent line? I'd rather not change the canister without knowing why fuel is getting into it. Does gasoline in the canister explain the engine run-on? I've read about ways to bypass or eliminate the canister, but these techniques also cause a gas smell. Are there any definitive tests that will narrow down the source of trouble?
FWIW, this vehicle is not subject to emissions testing.