Toyota Repair: 1990 Toyota Tercel fouls plugs, fuel air mixture, worn piston rings

Question
The spark plugs on my 1990 Toyota Tercel (venturi carburator) repeatedly foul after less than 50 miles driving and the car won't start until they are cleaned or replaced. I had a new carburator installed last year, and this problem showed up several months later. I had only driven the car about 150 miles with the new carburator.

Could this be related to the 02 sensor?

Anything else?

Any ideas would be helpful.

Thanks,
Lisa Church  

Answer
Hello Lisa, welcome to my expert page.
Oil fouled plugs are a sign of major engine problems, there is oil getting into the combustion chambers and the procees of normal combustion is trying to burn the oil along with the fuel/air mixture. Since oil is much less combustible than fuel, some of it will accumulate on the spark plugs and on the inside of the combustion chambers.
The reason for this may be leaking valve seals or worn piston rings, either one is an expensive repair, and no, the O2 sensor has nothing to do with it.