John Deere LX176 backfires, won't start

LilJayV10

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I was going to post this in the John Deere section but it doesn't seem anyone has posted there since last year. I hope to get some answers in here. I have googled my problem but haven't found any good answer.

I have a JD LX 176 w/ Kohler 14hp engine. Last year it didn't want to start. The engine would have to spin over for a while before it would start. It seemed to be worse when it was hot. It would also backfire out of the intake and the exhaust. I mean a really loud backfire, sounded like a shot gun.

I mis diagnosed it as a valve problem. Took the head off, lapped the valves, new head gasket, adjusted the valves and it still did the same thing. It sat all winter and today I decided to mess with it again. It started up twice and ran fine. I had the valve cover off it still so I shut it off and put it back on.

I tried to start it again and it started doing the same thing. It will spin over and will eventually backfire. I have an inline spark tester in it and it is getting spark.

I know that it is capable of running because it did it twice.

I have read it could be the flywheel key or some part of the ignition system. The coil was replaced last year but didn't make a difference.

I've been working on cars for 15 years now but these small engines seem to give me fits.

Any help would be greatly appreciated. The grass is growing and my wife is wanting to know when I'm going to fix this thing.

Any help would be greatly be appreciated.

Jason
 

Rivets

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Can you give us the Model, Spec and serial numbers for this engine. It would help us help you. Back fires on small engines are caused by bad flywheel key, too rich fuel mixture and/or valves and valve timing. From what you describe I would lean to a fuel mixture problem. Too rich. Have you tried leaning out the carb. Does it do it all the time or only on start up?
 

LilJayV10

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Engine code is FC420V-AS10
E/NO is FC420VA36622

It has a new carb on it from the dealer. It acts the same as it did with the old carb.

When it ran today, I choked it and it fired right up the two times. Now it won't run at all.
 

Rivets

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Would you check the spark plug right after you try to start it. Is it wet? If it is dry, my next step would be to check for a sheared fly wheel key. Keep me posted, have to go to work.
 

Rivets

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Engine is running way to rich, flooding on start up. Have you tried starting with no choke and half throttle. Does the carb have any adjusting needles? If it does set the high speed at 1&1/4 turn out after lightly seated and the idle 1 turn out after lightly seated. Also, the float level may be set to high.
 

LilJayV10

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I have tried different throttle positions and they haven't made a difference. I will check the carb adjustments tomorrow.

It acts the way it did with the old carb on there too. Is there a next step after the carb adjustments?

I appreciate your help.
 

Rivets

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Have you checked the flywheel key?
 

LilJayV10

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I haven't checked the key. I guess that's where I'm headed next. What's the best way to pull the flywheel off? I'm sure they sell a special tool for it. It looks like I could make something out of square stock steel, drill/tap the center and drill two holes to put bolts through.
 

mirassou

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When you shut it down, are you letting it idle first? If so, you run the risk of backfiring on shutdown and potentially blowing out the muffler. When you shut down, if the mower is at idle, you still have fuel flow, which then flows down into the engine setting up a beautiful potential for backfire.

On shutdown, try running at full throttle, then turn off the key.
 
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