stumped

[edurep]

B&S 18.5-31p777 new plug,new carb,new coil,valves adjusted. It will not start. It backfires when cranking.

 

[Scrubcadet10]

Check the flywheel key.... remove the crank nut or bolt, and you should be able to see the key, it should line up to make a perfect square in the keyway.
Also, i believe this is the model that has issues with the camshaft lobes wearing out prematurely... not sure though,.

 

[edurep]

Thanks, but I forgot to mention that the flywheel key was checked. ok

 

[Scrubcadet10]

i would remove the valve cover, and spin the engine over by hand and look to see that each valve has the same amount of travel as the other.
What's the backstory on this engine? Did it sit for awhile, or has it been running great and you went to start it and it said, "Not today!"?

 

[tom3]

The backfiring tells you it has spark, fuel and compression. Not at the right time. I've seen plastic cams and even a plastic drive gear on the crankshaft. Looks like you've hit all the other things it could be. Internal?

 

[slomo]

The backfiring tells you it has spark, fuel and compression. Not at the right time. I've seen plastic cams and even a plastic drive gear on the crankshaft. Looks like you've hit all the other things it could be. Internal?

Exactly, check the camshaft.

slomo

 

[cpurvis]

Did it do this before you adjusted the valves?