My Sears mower has a 15.5 briggs and stratton engine that is 6 years old and is having trouble starting. Sometimes when I turn the key, the motor will turn 3/4 of rev and stop due to hard compression. I can hand turn the engine past this sport sometimes and the engine will begin to turn over. Even then it takes 5 - 10 seconds for it to fire off whether I choke it or not. Then it spits out a gulp of gas and a little oil from the exhaust and runs fine for the rest of the afternoon.

I have been told the valves are carboned over. I am looking for a fix. The mower was turned upside down two years ago on a hillside. This may be a reason for the problem. Does anyone have any solutions?

Thanks, Darryl

I had a mower that did something similar, it turned out to be a bent shaft. Have you hit any solid objects?

No, not lately. However my brother had similar problems that indicated a carborator selinoid switch. My cylinder was filling up with gas, which apparently was building up excess pressure while trying to start it. When it did start, it would spit a bunch of gas and a little oil through the exhaust. I took the carborator selinoid off and had it checked and it was good. The salesman told me to take my carborator off and clean it out good especially around th needle valve. I did this and the motor has started on the first try every time since. I do not see any excess gas in the carborator after the motor is turned off and it turns over easy now. I guess I had junk in the gas that caused the needle to stick open. Thanks for the help and maybe this can help someone else with a similar problem

Hi,
The valves need to be adjusted. There is an answer to that on the Power Tools page that involves an instructional video on YouTube. YouTube - Lawn Mower Repair Valve Adjustment
Peace,
Clarke

Thank you crigby, I have had the same problem for years. Went through a battery every year. Fixed it in 15 minutes with your help.