What was wrong with this mower?

[PTmowerMech]

Thinking about the fuel & air flow system, since the timing and everything related has been covered, Maybe something jarred the carb or broke something on the intake. Nothing I can think of along those lines seems plausible.


I'm guessing the coil wasn't damaged or moved, since it doesn't touch the flywheel.

Short of the flywheel key being damaged, I can't see anything in or on the engine changing enough to not fire and run (even roughly).

My final answer (without phoning a friend) is something came loose in the carburetor.

 

[scoyote]

If you have checked all the normal problem boxes and still no start or rough run---aside from a cracked plastic intake manifold--i would guess your bade bolt totally backed off or your blade adaptor has one of those flimsy keys and it stripped or the cast iron has broken away??

 

[jdtm]

was your issue with the blade or the blade adaptor ?

The blade and blade adapter were OK. However, that is a reasonable guess. The standard flywheel on an engine made for a mower has very little inertia, so without the added intertia from the blade, starting would be difficult. Maybe it would not even start. I am unsure on that.

 

[Scrubcadet10]

Here's a hail mary.....
was it out of fuel?

 

[Scrubcadet10]

The blade and blade adapter were OK. However, that is a reasonable guess. The standard flywheel on an engine made for a mower has very little inertia, so without the added intertia from the blade, starting would be difficult. Maybe it would not even start. I am unsure on that.

I've attempted to start pushers without a blade, ITS VERY hard, but can be done. expect a few pulls to jerk out of your hand.

 

[jdtm]

I dunno.. throttle shaft somehow got wedged shut?

Now you are thinking out of the box, and that will be helpful. But no, the throttle was OK.

HINT: One of my original tests would technically be called an asymmetric test. An asymmetric test will either find if something is OK or bad but not the opposite. For example if you look under your car and see no puddle, you know that you do not have a major coolant leak. However, if there is a puddle, it may have rained recently, or a dog may have visited the area. Or you may be leaking coolant.

 

[jdtm]

If you have checked all the normal problem boxes and still no start or rough run---aside from a cracked plastic intake manifold--i would guess your bade bolt totally backed off or your blade adaptor has one of those flimsy keys and it stripped or the cast iron has broken away??

It is unrelated to the issue, but I use this mower as a cheap brush hog sometimes. After going through blade adapters on a routine basis, I made a two-part adapter that allows some motion when there is a hard impact. It is much easier on the internals, and I have never lost another blade adapter or flywheel key since making the change. Everything connecting the blade to the crankshaft was OK.

The plastic intake manifold cracking is another good guess, but it was OK.

 

[jdtm]

Thinking about the fuel & air flow system, since the timing and everything related has been covered, Maybe something jarred the carb or broke something on the intake. Nothing I can think of along those lines seems plausible.


I'm guessing the coil wasn't damaged or moved, since it doesn't touch the flywheel.

Short of the flywheel key being damaged, I can't see anything in or on the engine changing enough to not fire and run (even roughly).

My final answer (without phoning a friend) is something came loose in the carburetor.

I was actually thinking some strange carburetor problem myself when it first happened and I did the initial tests I described. However, I could not come up with a reasonable scenario either, and as it turns out, the carburetor was OK.

I was suspicious of the coil thinking an internal connection got damaged with the jarring. However, it was OK.

 

[PTmowerMech]

@Scrubcadet10 , I'm thinking that if no one had responded, we would've already had the answer by now.

 

[jdtm]

@Scrubcadet10 , I'm thinking that if no one had responded, we would've already had the answer by now.

Probably not. I was originally thinking that I would give the game about a day. By now, I have explicitly stated that most of the parts were OK. There are not all that many things left to consider.