I was given a non-running mower with a B&S 500 series ~4.5 hp 158cc engine. The mower is three years old. I was told it did not run very well last year or this year. Now it does not run at all. The mower had way too much oil in the crankcase, so I dumped all the old oil and filled to the full mark on the dipstick with fresh oil.
I emptied the old fuel and replaced it with fresh fuel, cleaned the carb, replaced the carb diaphragm, and put in a spark plug from another running mower. It still does not start. I know the primer works because I can see it shoot gas into the carb (I had the air filter screw in the carb without the filter box at the time).
I checked for spark and noticed something: the ignition wire is worn through where the wire comes out from under the engine shroud. When I checked for spark, the bare spot on the wire would arc to the shroud, but when I grounded the tip of the spark plug, the the arcing at the wire stopped. Could this be the cause of the problem? Is there some way I can check without buying a new ignition module?
I thought maybe one of the valves was sticking so I removed the cylinder head (flat head engine). There was some carbon, but the piston bore looked good and the valves and piston appeared to move in time. I rubbed some oil on the cylinder walls before I put the head back on. After I put the head back on I primed the carb, pulled the cord, and the mower ran... for about ten seconds before it quit again. Now the mower will not start.
Any ideas on what to check next?
I emptied the old fuel and replaced it with fresh fuel, cleaned the carb, replaced the carb diaphragm, and put in a spark plug from another running mower. It still does not start. I know the primer works because I can see it shoot gas into the carb (I had the air filter screw in the carb without the filter box at the time).
I checked for spark and noticed something: the ignition wire is worn through where the wire comes out from under the engine shroud. When I checked for spark, the bare spot on the wire would arc to the shroud, but when I grounded the tip of the spark plug, the the arcing at the wire stopped. Could this be the cause of the problem? Is there some way I can check without buying a new ignition module?
I thought maybe one of the valves was sticking so I removed the cylinder head (flat head engine). There was some carbon, but the piston bore looked good and the valves and piston appeared to move in time. I rubbed some oil on the cylinder walls before I put the head back on. After I put the head back on I primed the carb, pulled the cord, and the mower ran... for about ten seconds before it quit again. Now the mower will not start.
Any ideas on what to check next?