Z121S Bogging down when load added to engine.

[wiredhot]

It has a Kohler ZT720. When I was trying to mow earlier it would bog down and acted like it wasn't getting enough fuel or too much fuel. I tore down the carburetor on went through it with a fine-tooth comb, nothing there. So I went through the fuel pump and verified it was pumping the proper amount of fuel. I have pulled the fuel tank and drained it. It has been put back together and it is still bogging down when any load, driving or blades, is put on. I have a few videos of it. One of me on the mower, the other I had my son sit on it and actuate the PTO switch.

https://youtube.com/shorts/43hKeujJvdo?feature=share

Is there anything else I might want/need to check?

 

[wiredhot]

Forgot to mention, I put in a new fuel filter...

 

[bertsmobile1]

Got to be the governor

 

[sgkent]

I don't know the engine but in general, if an engine has a bad head gasket(s), that can cause issues of bogging down under load too. I'd at least check the head gasket torque. Bad spark plugs or ignition wires can cause it too. We had a 1968 Chrysler Newport that used to buck like crazy going up hills. It only had about 20,000 miles on it. Several carbs later, fuel pumps, plugs, fuel filters, etc., the dealer's mechanic changed the wires cause they were about the only thing left. That fixed it. The wires were breaking down under load. When under load compression pressure is higher, and that raises the voltage a plug will fire at. That additional voltage was causing the ignition wires to break down.

 

[lugbolt]

that video is mostly useless, the sound quality....the sound is often distorted horribly because the noise is louder than the mic can handle

Pull one plug wire off. Then go start the engine. Does it run ok? Does it run at all? If nothing changes, put that plug wire back on, then pull the opposite one off and see if anything is different. This eliminates a spark or internal engine issue. If for some reason you pull one of the plug wires off and the engine won't start, the other cylinder is not firing, and is probably the cause of your loss of power.

looks like thd governor is working fine.

i know you cleaned the tank but did ya clean out the pickup tube/shutoff valve assembly? The originals were just a tube and a valve, the newest revisions have a little screen on the tip. If you don't have the screen on yours, blow some air through the pickup tube/valve assembly and see if anything comes out. I've seen TONS of them get grass/dirt up inside the shutoff valve, restricts fuel flow and causes a big time loss of power, usually under a load.