Replaced sheared flywheel key, engine fires more, but still doesnt start.

[L.Skynrd]

Hello Everyone, I made a post here last week about my briggs and stratton 3hp. I replaced the breaker points ignition to the electronic system. It had a flywheel key that was sheared in half, and thus I was unable to start it. I have replaced the key, and torqued the engine to the proper specs. I sprayed starter fluid into the carb, and got more firing than with the sheared key, but still it will not start. I am just wondering where to go from this point. Also, I just wanted to thank everyone for their help, as this project is a learning experience for me.

 

[karl]

Ok, is the spark bright blue? Find somewhere to ground the plug, cliplead might help. Anyways,

With the shroud off the motor, spin the flywheel backwards, against compression stroke.

It should bounce back if the engine has adequate compression to run.

 

[TedP]

I have to wonder how a horizontal shaft Briggs engine sheared the flywheel key. It happens on vertical shaft engines when a mower hits a stump or something. What could have happened on a horizontal? Note, if the key you installed is even slightly sheared, try a new one. It doesn't take much.

 

[jmaack]

I have to wonder how a horizontal shaft Briggs engine sheared the flywheel key. It happens on vertical shaft engines when a mower hits a stump or something. What could have happened on a horizontal? Note, if the key you installed is even slightly sheared, try a new one. It doesn't take much.

Mine sheared also, I was told repeated cranking when not starting and misfiring causes it. Was my first also.

 

[TedP]

Mine sheared also, I was told repeated cranking when not starting and misfiring causes it. Was my first also.

Not likely repeated cranking, but more likely a misfire that tried to send the flywheel in the opposite direction. It always amazed me how little a crease in that key would stop it from running. Just the slightest visible line would do it, too. I've tuned up hundreds of them, if not more, and every one got a new key, oil seal and plunger, in addition to the points and condenser.

 

[karl]

It always amazed me how little a crease in that key would stop it from running.

With points yes , but he upgraded to magnetron ignition, no breaker points. It can be 4+ degrees advanced or retarded and still run.

I was trying to narrow the problem down for the op , If he has good spark, fresh timing key as the op stated, and compression, I would lean towards a carburetor issue, most likely.

 

[TedP]

With points yes , but he upgraded to magnetron ignition, no breaker points. It can be 4+ degrees advanced or retarded and still run.

I was trying to narrow the problem down for the op , If he has good spark, fresh timing key as the op stated, and compression, I would lean towards a carburetor issue, most likely.

Yep, if you've got compression and spark, it's most likely fuel. He didn't say if it would start on ether. I'd also pull that crankcase apart and make sure the timing marks on the cam and crank are aligned. Cam timing could be the misfiring, while still feeling compression.