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I was given a mower after it hit a large root and wouldn’t start any more. I have already:
-replaced the flywheel key
-Straightened the driveshaft (following Steve’s small engine saloon)
-emptied/cleaned gas tank and fuel line
-added fuel
-checked oil
-Disassembled carb and cleaned with compressed air (didn’t have carb cleaner)

the air filter is full of oil so I removed it and tried to start mower. It doesn’t catch, then “pops” with a little white smoke out of the carb. Repeated pulls just give this pop like a backfire, but it won’t catch.

I tried starting it with a tsp of gas directly through spark plug hole, and it’s the same. If I install the (old) air filter, I get absolutely nothing, so it seems like an air/fuel problem but I’m not sure what to try next. Should I try spraying carb cleaner or starter fluid in the carb?

Edit: I read about hydro lock and flooded engines, so I pulled the spark plug and cycled the engine several times. Now it no longer backfires but it still won’t catch.

Engine model #? Years ago, I had a 12S912 on a pressure washer. IIRC, it was gov/oil slinger failure with camshaft damage. Pull the valve cover and see if valves operate properly. Do both valves close as piston approaches TDC on compression stroke? Also, did you wire the the carb jets/orifices? A disassembled carb in a parts washer is a good idea.

dougand3 said:

Engine model #? Years ago, I had a 12S912 on a pressure washer. IIRC, it was gov/oil slinger failure with camshaft damage. Pull the valve cover and see if valves operate properly. Do both valves close as piston approaches TDC on compression stroke? Also, did you wire the the carb jets/orifices? A disassembled carb in a parts washer is a good idea.

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It’s an 11P902-0809 - B1. I’m going to pick up some carb cleaner tonight and give everything a good spray. i need to find a good fine wire—Bristle from a metal brush?

Landline telephone wire works well for carb holes. But if you can't put fuel in plug hole, re-insert plug, pull rope a few times (maybe 10x if floody), and get a 2 sec run....it's not an air-fuel problem. Think compression or spark/timing problem. See if valves work.

Check the flywheel key again. If not properly torqued when you reassembled, you will probably find it sheared.

Rivets said:

Check the flywheel key again. If not properly torqued when you reassembled, you will probably find it sheared.

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I was afraid of that but I didn’t check the key again yet. Sometimes it jerks when pulling, but not nearly as bad as before.

When you say “not properly torqued” do you mean not tight enough or that I need a torque wrench?

I’ll look at valves too.

Be careful running any wire thru the bolt screw jet assembly as the 697355 is NLA.

Yes you need to be using a torque wrench to torque it to 60 ft-lbs going by the APSI 67 or if going by the power portal 44 ft-lbs.

Just buy a new carb off Amazon. Prolly under $20. It's just not worth the trouble trying to clean an Ethanol Damaged carb. Many come with air cleaner, fuel line and spark plug.

biggertv said:

Just buy a new carb off Amazon. Prolly under $20. It's just not worth the trouble trying to clean an Ethanol Damaged carb. Many come with air cleaner, fuel line and spark plug.

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Yea just keep helping the Chinese take over the American businesses. The involved carburetor is dead simple to clean and repair.

Rivets said:

Check the flywheel key again. If not properly torqued when you reassembled, you will probably find it sheared.

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Yep. Key sheared completely in two. Guess I’m going to get a torque wrench. I’m going to replace that key and then look at the valves if it still won’t start.

The end…for now. I replaced the flywheel key, tightened it appropriately and the engine started right up. I now realize I sheared the last key off from the first pull of the starter. It tried to start just that one time and never would again. Thanks for all the help!

Fixing the self propelled is a task for another day…

StarTech said:

Yea just keep helping the Chinese take over the American businesses. The involved carburetor is dead simple to clean and repair.

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The dead carb was prolly made in China too... As is whatever device you are using Right Now...

animattor said:

The end…for now. I replaced the flywheel key, tightened it appropriately and the engine started right up. I now realize I sheared the last key off from the first pull of the starter. It tried to start just that one time and never would again. Thanks for all the help!

Fixing the self propelled is a task for another day…

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Thank you for letting us know your conclusion. Too many ask for help but never return to add what solved their issue. Inquiring minds need to know what solved the mystery.

TiIngot said:

Thank you for letting us know your conclusion. Too many ask for help but never return to add what solved their issue. Inquiring minds need to know what solved the mystery.

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And the saga goes on…
One repair I didn’t mention was fixing the height adjustment. The arm connecting the front wheels to the back was missing a bolt. I didn’t have the right one on hand, so i improvised by putting two nuts on a tiny piece of threaded rod. Well the nuts worked their way off, and the rod fell out. Without that connection the mower nose-dived into the dirt, and the blade tried to dig its way to China. It only dug down about 5cm but it was far enough to shear off the bolt holding the blade and…shearing off the flywheel key again. So now I get to replace the flywheel key again and extract a broken bolt from the drive shaft. If I wasn’t a cheapskate who likes a challenge I think I’d give up!

Glad you fixed it. Been working on small engines for over 60 years. Please help me learn how do-it-yourselfers might learn to straighten a drives haft.

Etbrown44 said:

Glad you fixed it. Been working on small engines for over 60 years. Please help me learn how do-it-yourselfers might learn to straighten a drives haft.

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I followed this video.
It wasn’t easy (i.e. hard but not complicated) but I got the shaft from being over 1cm off down to about 1-2mm. Not perfect but much improved. After my latest incident I still need to check if the shaft is bent again or not.

biggertv said:

Just buy a new carb off Amazon. Prolly under $20. It's just not worth the trouble trying to clean an Ethanol Damaged carb. Many come with air cleaner, fuel line and spark plug.

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After hitting a root & stopping it’s almost garrantees it’s out of time!