I am new here so let me say thank you in advance for taking the time to read this.
I have a Yazoo Kees ZT MAX 61" Commercial with a 25 hp Kohler Command engine. Model # ZKH61253.
History: I have had the mower for about 7 years. I ran perfectly until last year. I started blowing a lot of smoke out of the exhaust and it would run for a few minutes and then I had to pull the choke for a second or it would die. I took it to a shop and they found that the fuel pump (mechanical on top of right valve cover) was cracked and blowing smoke into the carb. They replaced the fuel pump and let it sit and burn a tank of gas out and it ran fine.
Current Issue: I can start the mower and as long as I leave it sitting still it will run all day. Once I engage the blades or start moving it will run for a minute and then try to die, here comes the weird part...if I pull the fuel line off of the outlet side of the fuel pump (fuel pump is still pumping gas out) and stick it right back on really quickly the mower will recover and run fine for a few minutes and then do it again....if I am not so fast it will die and then start right back up (with the choke out) and run fine for a few minutes. I have not been able to put any kind of pattern together...sometimes it will run fine for 15 minutes without dying and sometimes 15 seconds.
What I have tried: Draining all the gas and starting with new gas.
Replacing fuel lines.
Replacing fuel filter.
Cleaning carb.
Running gas directly to the carb from a container (gravity feed).
Removed probe from the electronic fuel solenoid (safety shut off located on back of carb).
I just can't figure out why it will run fine for a bit and then just quit. Any suggestions that I haven't already tried or do I need to perform an exorcism on it?
With everything you discribed, it sounds like you might have a fuel cap that is not venting. If that is the case your fuel tank is creating a vacume and when you pull the fuel line off, you are in "effect" relieving that vacuume. It is almost like when you put your finger over the top of a straw filled with liquid. remove your finger, and the fluid flows out.
Sorry, I forgot to mention that one. I tried that as well, loose, completely off and still the same thing. This thing has me completely baffled. I even tried switching to the other tank and still no go. My first thought was that the fuel lines were collapsing since they were originals but after I replaced them and the same thing happened I just started trying random things that I thought could be causing a fuel stoppage. I am going to replace the plugs (last ditch effort) and try to mow the grass. If that doesn't help (I doubt it will) I am going to pull the carb off, take it apart, soak it overnight and rebuild it to see if that helps. I read somewhere about a guy having the same problem and he bought a new carb and put on it and it still did the same thing and last time I checked he still didn't have it fixed. I can still mow the grass but it uses twice as much fuel (pulling the fuel line off and squirting it all over me and the mower) and takes twice as long.
Well, I don't know what to say...either the mower gods have descended upon me with grace or my curse has been lifted. My mower is now working fine, no stalls, no issues. I have no idea what happened but i'm not going to complain.
I had a similar problem with a Craftsman single cylinder rider that would start up after sitting and run for a few minutes, sputter and die. Problem was not with fuel flow, but with a small clear piece of plastic acting like a flap over the fuel metering inlet in the bowl going to the carb. At times it would be off the inlet and it ran fine, then it would get over the inlet and starve the engine for fuel. Being clear it was difficult to see. I found it by running a wire through the metering hole! Hard to say what caused your problem.
