John Deere JS46 - Briggs Engine - Hard Starting Update

[mgilbert]

I asked about this recently, but wanted to start a new thread so it would get read by new eyes...

I have a John Deere JS46 that is hard to start. It has a Briggs 190cc OHV engine. When trying to start, all I get is pfffft, pfffft, pfffft, pfffft, pfffft, pfffft. It's hitting, and almost starts, but never quite catches hold. It backfires occasionally when trying to start as well. It started as a hot engine problem. Now it's the same cold. Someone suggested adjusting the overhead valves. I checked them, and they weren't far off, but I adjusted them anyway. It made no difference whatsoever, so I don't think that's the problem. I checked the flywheel key, and it is not sheared.

I understand that this engine has some type of system that relieves some compression during starting, to make it easier to turn over. I have no idea how this system works, but could it be the problem? I don't see any obvious signs of a blown head gasket, but maybe that doesn't mean there isn't one.

I'm good with mechanical things, but have little experience with small engines, and that's what is needed here.

Does anyone have any idea what to do next?

Thanks...

 

[Mikel1]

If you put some fuel into the cylinder and then try to start. Does it startup?

 

[mgilbert]

If you put some fuel into the cylinder and then try to start. Does it startup?

Are you suspecting a fuel flow issue? I haven't considered that, since the mower runs fine, if I can ever get it started.

 

[Mikel1]

Possibly since it's hard starting and you have already checked the valve clearances & flywheel key.

 

[JD is best]

Check your spark, ground it against the engine and pull the cord a few times. Blue is good yellow is bad.