Hi there I'm new--found this site thru an Internet search.
I've got an 86 tercel that is leaking gas and dieseling.
It's also slow to ignite and reeks of gasoline even when the gas pedal isn't depressed.
It accelerates fine and idles well.
Diesels after turned off.
What are some pet problems that match these symptoms?
We've gone thru some troubleshooting, but my husband and I are learning and likely
missed something.
Sounds like a couple of problems. Most common cause of fuel leak is the diaphragm on the carb, on the "back" side, side toward the windshield. inspect the heat shield in the area on the side where the throttle cable is located, the one under the carb, if the diaphragm is leaking you will see fuel stains on the heat shield. Also check the fuel line between the fuel pump and the carb for leaks. And see if the float level is correct though the site glass on the front of the carb (you likely need to clean it off and use a flash light). If the float or needle valve is not stopping excess fuel from coming in the carb it will run rich, flood the engine, give poor gas mileage and smell of gasoline. Sometimes you can just remove the top of the carb (watch out for the small parts!) and clean the needle valve, or replace it. Might cleanout the whole carb while the top is off. Better yet get a rebuild kit and rebuild the whole carb, not too difficult but you need a good clean table to sort out the tiny parts, and get it back together correctly.
Check the fuel cut-off solenoids are working (see the test in the Factory Service manual-FSM), a fairly easy test. Often a vacuum leak will make it run lean and cause the dieseling, and give poor economy. Inspect all the vacuum lines for leaks or disconnected vac lines, I would also carefully check the vac line diagram in the FSM for correct routing of all the vac lines.
You also might check your ignition timing is correct, you will need a timing light, or rent one from an auto parts store. Factory spec is 5 deg BTDC, I recommend using 10 deg BTDC. You get better economy, power and lower exhaust temps and have much lower risk of damaging an exhaust valve.
If you have a lot of carbon buildup in the cylinders you can chemically remove it by soaking the piston tops in Gumout overnight, and starting it in the morning. You flood the engine by pouring Gumout down the carb while it is running until it stalls out, or you can put it in through the spark plugs holes and replace the spark plugs.
