Kohler dieing!

Since figuring out the electrical gremlins on my ZTR, I have a new one. Ill try to explain the best I can. 2 tanks, hold 5 gallons each. M=Mower got to where it would only run 10 minutes or so, and then just die. If I was fast enough to kill the deck, and move the choke to about 3/4, I could make it back to the building. Almost the exact same time, the engine on my other ZT started having very similar symptoms, and after investigation, I found water in my gas can. (Still not sure how that happened)I drained and cleaned out the tank on ZTR #2 and all is fine. On the first one, I drained the fuel, and sure enough, water in the fuel. I took both tanks off and have let them sit in the sun, and are dry. I replaced the fuel lines, since they were off, and getting old, as well as a new fuel filter. I removed the carb and cleaned what little gunk was in there, which wasn't anything more than a little drop of water or two. I also removed and checked the valves, which were fine. After getting it all back together, I put a couple of gallons in each tank. The engine started, and ran fine, so I let it sit for a few minutes, and it never missed a beat. So I get on, head to the yard, make 2 rounds and it starts dieing again. I managed to get it back to the building, and keep it running by choking and playing with the throttle, but I did notice that the filter had no fuel in it. Not just a little, NONE. If I choked it, fuel would pull into the filter and it would stay running. It finally got to where it would no longer stay running, but I sat there for a few seconds and watched the filter and the fuel slowly filled the filter back up. I can take the lines loose, and blow through the lines fine, plus with them being new, I don't think they are the problem. I can take the line loose at the pump and have feul coming out the line to the carb, and it does push fuel when I turn the engine over, but no real force behind it.

My next step was to check for spark. When the engine finally died, I pulled the wire on each cylinder and I have a good blue spark on each side. I cant even think its electrical, as choking helps for a moment, so I'm thinking the fuel pump isn't pulling the fuel FROM the tank to keep it running. Opinion?

Check the vent in fuel tank cap.

Those are fine on each tank.

Could be trash under the needle and seat.I have had times when trash got under the seat. Keeping it open flooding the engine. Then I have found trash on top of it. Blocking the fuel flow.

All of that's fine, but thanks for the suggestion.

The empty fuel filter sounds like an air leak in the line between the tank and filter. When it's running, the pump is pulling vacuum on the line, drawing in air. When it shuts off, the fuel slowly refills the filter because the vacuum has stopped. Any chance the change over valve is leaking vacuum? Do the tanks pull off the bottom or do they have dip tubes? If they have tubes, they may be loose or have anti siphon valves or air bleeds. Question is, why did it work before but not now? Could try dropping a fuel line directly into the top of the tank from the pump as a test.

Not sure how the plumbing is arranged, but pumps don't like to have the suction side restricted with filters. It may work better with the filter on the pressure side of the pump, if it's not already that way. Also fine mesh filters work better than paper filters with the impulse pumps. Have you looked into the pump for trash under the valves or restricting flow?

Steve,

Both valves are on top of the tank. Each has a line that runs to a tee, from the tee to the filter, then to the pump, then to the carb. This is the factory setup. I have new lines from the tank all the way to the carb, all dealer purchased for this mower, not something I fabbed. I assume the pump is OK, since it will pump gas out of it when cranking, but as I said, there is no real pressure to it. I can place my finger over the outlet and stop the fuel from coming out while pumping. Both dip tubes appear to be good, no visible cracks, and since the valve is made in such a way the tubes are part of it, and they are like 90 bucks each, I reused them. They could indeed be a problem though. I may try to putting the filter on the outlet side and see what happens. Oh and the filter is new and the one Kohler says to use, and Cub Cadet.

John M,
sounds like you have an unusual problem, need to think outside the box to determine if you have a fuel or electrical issue.

I would remove the air filter and have a can of starter fluid. When engine starts missing I would give it a squirt of Starter fluid and see what happens.

What do the plugs look like? Have you replaced them yet? I had an old single cylinder briggs that would run for 3 minutes then shut off. Bad plug.

I've seen a single cylinder briggs, flat head, would run for a few minutes before it started missing and blowing black smoke. Intake valve seat recession. I had to shorten the valve stem to adjust the valve. Used valve grinding compound and lapped the valves.

If your kohler is a command, then it has hydraulic lifters. If not have you checked your valve clearance?

I bought a used kohler command with 400 hrs on it. I had to grind the valves on one head. I think the previous owner didn't change the oil. The engine started burning oil, carbon deposits under the intake valve which held the valve open just enough to mess things up.

Saw a kohler off a cub cadet. There was so much grass under the flywheel cover the one head dropped a valve seat. Remove cover and look for grass clippings, even a mouse nest blocking the cooling fins.

Think outside the box, run test to isolate your problem.

I know it gets expensive to replace parts, but that may be your only option. I'm a pack rat and stock used small engine parts. I would replace the fuel pump, plugs, ignition modules one at a time. Even clean the rust off the flywheel while replacing the ignition module.

Let us know what you find. Good luck.

Maybe try an electric fuel pump and see how it behaves.Seems like you are loosing fuel pressure as it warms up. The fuel filter should be at least 1/2 full running wide open under load, since it is empty I would venture a guess the fuel pump is failing.

Hey George,

Plugs arent new, but were put in this season and havent seen more than a couple of hours total run time, but I plan to change them today. They still looked fine, but its only a couple of bucks so they will be changed.

My Kohler is a Command, but the rockers are non adjustable, and the heads were replaced last year when I repalced the head gaskets due to leaking into the cylinders. (This is a vertical shaft engine.)

I still think its realated to the fuel pump, as I mentioned when it dies, I can choke it and it runs enough to get back to the building, and it will suck in fuel into the filter when I choke it just sitting there and it starts to die. I will be going through the rest of what you suggested though, just to make sure all of thats OK.

Thats exactly what Im thinking, and after some checks this afternoon, Im taking the fuel pump off of my golf cart and rigging it up to see what happens.

I vote with GFJ, also might be some thing in the valve in the tank. OR getting over the end of the line in the tank.