QuestionMy Craftsman riding lawn mower has a B&S 17 IC OHV engine. A cold engine starts and runs fine for about 15 minutes and then starts to misfire and will stall. It restarts OK but misfires and stalls. I have to stop mowing. I have cleaned the spark plug, replaced the fuel filter and operated it without an air filter. None of these helped. I'd really appreciate your advice.
AnswerHi Charles,
You will need to determine if the problem is a lack of spark or a lack of fuel flow. Right after it quits, remove the spark plug, reconnect the wire and lay
it against the engine head. Pull the engine over and watch for spark at the plug's electrode.
If no spark I would replace the ignition coil.
If good, then try to start it while squirting fuel or starting fluid into the carb's intake. If it starts and you can keep it running by adding fuel, then the
carb most likely has dirt, debris or gummed fuel inside.
You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air. Probe each and every hole with a small wire. Adding a carb rebuild kit wouldn't hurt either.
Another possibility if the problem is fuel related: Check the gas cap to make sure it is venting and not causing a vacuum in the tank. Also check for water
in the fuel tank.
Let me know how you make out.
Michael
