CV730 has me stumped

W

Will9000

Forum Newbie
I have a cub cadet commercial mower with a Kohler Command CV730 on it. It starts up fine, idles decent, but when I rev it, it seems to be loading up with fuel. It struggles to rev smooth. When I engage the PTO it falls flat on its face. It starts sounding like a diesel sputtering. Parts I have replaced trying to figure it out: Stator, voltage regulator, both coils, both spark plugs, idler pulley on deck (all the rest move free), carburetor, fuel pump, fuel filter, fuel lines, and both head gaskets. I don't know where to go from here. The only thing I noticed today was that the fuel filter doesn't have much fuel in it when I was revving. Anyone here that can help? I appreciate it!

Edit: I have also pulled the flywheel to make sure the key was not sheared. It was perfectly fine. There were questionable wiring changes made before I bought the mower, but it ran great until it didn't. The previous owner had removed the ignition and replaced it with 2 toggle switches. 1 to turn power on and off and the other is a momentary start toggle.
 
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You've replaced a bunch of fuel lines and stuff, have you tested the fuel flow? Disconnect line at carb, crank engine, see how fuel flows. Disconnect from pump, see how that flows by gravity. The fuel pickup could be clogged and restricting flow. If you remove gas cap and shine a flashlight, can you see the pickup? You can often fish it out and clean/replace filter. If there's a check valve, it may be sticky and need cleaning. Checking flow will tell you more than the filter. The orientation of the filter does more to determine how much air stays in it.
 
Mark H_NO said:
You've replaced a bunch of fuel lines and stuff, have you tested the fuel flow? Disconnect line at carb, crank engine, see how fuel flows. Disconnect from pump, see how that flows by gravity. The fuel pickup could be clogged and restricting flow. If you remove gas cap and shine a flashlight, can you see the pickup? You can often fish it out and clean/replace filter. If there's a check valve, it may be sticky and need cleaning. Checking flow will tell you more than the filter. The orientation of the filter does more to determine how much air stays in it.
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I forgot to list that as well. I've pulled both fuel pick-ups out (there's 2 tanks on this mower) and was able to blow through both with no problem. When I did disconnect the fuel line at the carburetor and turn it over, it seems to flow just fine. Is it possible that the pulse line for the pump is collapsing? I don't know how these operate, whether it's vacuum or positive pressure.
 
Will9000 said:
I forgot to list that as well. I've pulled both fuel pick-ups out (there's 2 tanks on this mower) and was able to blow through both with no problem. When I did disconnect the fuel line at the carburetor and turn it over, it seems to flow just fine. Is it possible that the pulse line for the pump is collapsing? I don't know how these operate, whether it's vacuum or positive pressure.
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The pulse line could have a crack or hole in it.
 
Tiger Small Engine said:
You have replaced a lot of parts. Try diagnosing the issue instead of throwing parts at it. List the problems and symptoms of the mower, then research online the possible causes of these symptoms. This focuses your efforts towards the possible solutions.
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While it's true that I've replaced a lot of parts, they were also necessary to replace. Example, when I took the bowl off, there was a large amount of corrosion, replaced carb. When I inspected the pulleys, one had a bearing completely separated. Replaced the bearing. Engine was running on 1 cylinder, replaced the coils and spark plugs, runs on both cylinders now. PTO bearing was crunching and didn't sound good, replaced it. This problem has been persistent through all of the parts that I have replaced. Now it's getting worse to the point that I can't really mow with it. At idle, it sounds like it's slightly missing and when you put a load on it (engage PTO or hydro pumps) it starts spitting and sputtering and struggles to do anything. When I turn PTO off, it takes the motor 10 seconds or so to return to a somewhat smooth RPM. Sometimes I can bring the rpm down and it will smooth out slightly. I'm posting here because I have run out of options. I've checked fuel, timing, compression, and spark. All seem to be as they should be. Am I missing something? Possibly, but that's why I'm here
 
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