Troy built push mower won't start

[twilson542]

I have a troy built 7.75, 175 cc 21" xp push mower that won't fire. Model # 11P02-0693-B1 Briggs engine. When I pull starter cord it seems to backfire a bit out carb but does not really ever catch to start. Here is what I have done. I put a brand new carb on after several attempts to clean old one. Looks like carb was not issue. New spark plug and it has a good visual spark. Pulled flywheel and put in a new key. Old one looked good. I do not have a compression tester, but compression feels good just at the pull cord. Not sure what to attack next. Any ideas? Thought about checking valve clearance. Never done this before, but does not seem to difficult.

Also checked little black wire for kill to magneto. Wire looks good. Tried to start with this wire connected and disconnected - no difference.

 

[shiftsuper175607]

I have a troy built 7.75, 175 cc 21" xp push mower that won't fire. Model # 11P02-0693-B1 Briggs engine. When I pull starter cord it seems to backfire a bit out carb but does not really ever catch to start. Here is what I have done. I put a brand new carb on after several attempts to clean old one. Looks like carb was not issue. New spark plug and it has a good visual spark. Pulled flywheel and put in a new key. Old one looked good. I do not have a compression tester, but compression feels good just at the pull cord. Not sure what to attack next. Any ideas? Thought about checking valve clearance. Never done this before, but does not seem to difficult.

Also checked little black wire for kill to magneto. Wire looks good. Tried to start with this wire connected and disconnected - no difference.

You have to narrow it down to either a spark problem or fuel problem...

Will it start with a spray of starting fluid?

 

[twilson542]

You have to narrow it down to either a spark problem or fuel problem...

Will it start with a spray of starting fluid?

No will not start with Starting fluid. Tried some fuel right into spark plug hole did not fire. Made me think spark is bad but when I pull plug and put up to engine to check I see a strong spark when I pull cord.

 

[Mikel1]

Was it backfiring thru carb before installing new key?

 

[twilson542]

Was it backfiring thru carb before installing new key?

Yes

 

[Mikel1]

I would check the valves.

 

[twilson542]

Was it backfiring thru carb before installing new key?

I am just closing the the thread with what was wrong. Opened up the engine and nothing was immediately visibly broken. I slide the timing gear off crankshaft and tried to turn the camshaft (by hand) and found the PLASTIC gear was free spinning on the camshaft. Replaced camshaft (Plastic again ugggh) and timing gear (replacement gear was metal) put engine back together and the mower fired right up. Why there is plastic gears in there is beyond me.

Around $120 in parts including the carburetor which I did not need. Guess I have a replacement one now.

Thanks for the replies everyone.