Gcv160 Won't start. Found oil on plug and air filter. Only backfires some of the time. Help me

hi try cleaning the carb or check your air filter box might be filled with oil so all you have to do is clean the air filter out with water let it dry and soak all the oil up with a rag or sponge. Best of luck!

Do you have a carburetor? If you do, it is set too rich. Also, your timing appears off. If you do have a carburetor, adjust the setting to the left a couple of turns. This will lean out the gas mixture. If you have a fuel injector, have the system checked. The air filter could be clogged and the fuel injector could be misaligned.

A backfire is often created because the timing is off, forcing the spark plugs to fire before the pistons get to the top of its power stroke, causing the mixture to burn prematurely.

carb needs cleanin or rebuild--getta clymermanual for procedure

check for spark is there a low oil shut off and the oil level is a little low ?

Have you checked Google I found this hopefully it's not your timing or it may be flooded but doubtful have you tried spraying starting fluid into the intake while cranking it

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u will find a lot of wiring diagrams and circuit diagrams and stuff like this at few sites I know with service like
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Have you checked the valve lash lately. Many times backfiring is from improper timing an valves not set correctly.

How much too much? If a whole lot, may need to check the plug and with the plug out, rotate engine a few times. After putting in plug try to start. If not, check carburetor for oil. Air filter should paper element should not have oil on it.

I hope this helps.

Have a look at these tips for troubleshooting starting problems with lawnmowers:

http://www.fixya.com/support/r9118692-lawnmower_not_starting

Hope this helps!