1991 GMC Jimmy, 4.3 liter 200,100 miles. Scotty, I have had this truck for about 10 years now with no major issues at all. My question is that there is always a gasoline smell, like it is running rich, when I stop. Is there any way to adjust the air/fuel mix or anything that I can do? Injectors are clean. Truck runs great, 17 to 20 MPG. Does the computer port (OBDI?) on this old a vehicle provide any useful information? Thank you!
You could check for OBD1 codes to see if the computer is reporting any issues. On a vehicle over 30 years old it could well be drippy fuel injectors and/or leaky fuel lines or evap system.
You'll need an OBD1 scan tool:
Thanks Chuck! The injectors and fuel lines seem solid, no leaks. I'll have to find an OBD1 scanner, there are some on Amazon but not for GMC's specifically. I'll count the pins and see if I can match one up. Also, I don't know what the "evap. system" is!
The OBD1 scan tool I pictured above (and the link showing how to use it) will generally do the trick. The "evap system" controls evaporative emissions from the gas tank and fuel system. Fumes are carried off to a charcoal filter via rubber hoses - all of which deteriorate over a period of 30 years.