Z725 mower shooting flames

JenJen

New member

Equipment
Z725 mower
Aug 24, 2022
17
0
1
Ohio
I'm on my 3rd Kubota zero turn. Most have been trouble free but this last one not so much. I was mowing yesterday for maybe 45-60 mins and it stalled. I turned the key to re-start and it cranked but acted a little fuel starved. I've had the clogged fuel tube issue in the past, but this was a bit different. Sometimes when warm, I have a hard time starting and have to play with the choke (and even though its been running, I may still need the choke for a second or two which seems odd to me). I stopped, turned the key again and I swear I saw flames coming out the back (muffler?). I stopped and hopped off the mower and the flames were out. i almost feel like I imagined it but I decided I was done for the evening. I just went to try again. It cranks but just doesn't turn over. I think I need a pro at this point. However, its tough finding someone available. Am I in this for a new engine? Its several years old but has under 300 hours. Thoughts? If i have to buy a mower, any pointers on buying a used one?
 

dragfan66

Member

Equipment
B7500 Z231KW G1800 L3350DT
Apr 12, 2020
56
55
18
Alabama
According to what I found, that should be a 25 HP Kohler CV742.

Did you check anything or just throw your hands up?

I know it is cutting season, but you need to check some things first.
Air filter, carburetor, fuel filter, spark plugs, etc., etc., etc.
 
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Donystoy

Active member
Lifetime Member

Equipment
LX2610HSDCC, B/H, Loader, plus numerous other attachments. B7200 sold
Dec 10, 2013
566
217
43
Binbrook, Ontario
My zero turn has the same engine. I have always had to have the choke on to start from day one when new. Even when hot. Makes a loud noise for a second and then fires up. Choke is then immediately pushed in. This procedure was explained when new by the dealer. Have never had this in the past even with older Kohlers.
 
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Soopitup

Active member

Equipment
BX23S
Oct 25, 2018
341
159
43
New England
I know nothing about the specific model for the record.
Gasoline engine?

Flames in the exhaust means you're either running too rich or the mix isn't combusting correctly due to either lack of compression or ignition.

If the engine feels like it's running lean but you have flames you may have a ignition problem. How do the spark plugs look?
 
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JenJen

New member

Equipment
Z725 mower
Aug 24, 2022
17
0
1
Ohio
According to what I found, that should be a 25 HP Kohler CV742.

Did you check anything or just throw your hands up?

I know it is cutting season, but you need to check some things first.
Air filter, carburetor, fuel filter, spark plugs, etc., etc., etc.

Threw my hands up and called a mechanic :) findings in my original post. Thanks for your response!

PS I checked the air and fuel filter (clean), not sure what to check on the carb and did not check the spark plug. The engine went whomp, whomp, whomp and never got enough momentum to actually start. The diagnosis was disappointing on such a low hour engine.
 
Last edited:

JenJen

New member

Equipment
Z725 mower
Aug 24, 2022
17
0
1
Ohio
I know nothing about the specific model for the record.
Gasoline engine?

Flames in the exhaust means you're either running too rich or the mix isn't combusting correctly due to either lack of compression or ignition.

If the engine feels like it's running lean but you have flames you may have a ignition problem. How do the spark plugs look?
Thanks for the reply. I put the diagnosis in my original post. I don't know a lot about engines but I am pretty in tune with what it should sound like. When trying to start after the flames it made a kind of whomp, whomp, whomp sound. Definitely not what I'm used to hearing. I think he said a valve was stuck (among other things)? I hope I'm not being taken for a ride...