Mower runs fully choked

[Tommy S]

I have a ZG227 Kubota that will run with the choke pulled but dies when it is pushed back in. This issue began when the mower stopped running while in operation. I checked and found that the fuel pump was not working. I replaced the pump as well as the filter just downstream. By the way, this is the second pump to go out in two years.

The mower would not start so I checked the fuel flow at two locations; the run/stop valve and the carburetor inflow tube. I have good flow at each.

Next I removed the carburetor, checked the float, and cleaned the housing and passage ways. I reinstalled the carburetor and checked the work to be sure all was secured.

Now the mower runs with the choke pulled out but dies as soon as it is released.

 

[1970cs]

I would suspect the carb still. If you have to pull the choke to get it to run or it's fuel supply issue.

Have you tried to run it off of an independent clean fuel source?

Pat

 

[Dave_eng]

On gas engine carbs, a complete disassembly is necessary to get dirt out of tiny passages.

In the picture below, there is a long brass part called an emulsion tube identified as A which is held in place by the main jet identified as B.

The main jet needs to be removed and then the emulsion tube persuaded to fall out.

Along the side of the emulsion tube are tiny holes. You need to use a strand of fine wire to clean these holes. Take a short piece of multi stranded automotive electrical wire and strip off the insulation to be able to remove one strand. Use the strand to poke the tiny holes clean.

Now for the big word of caution. The main jet screws into the center of the carb, is made of brass and easily damaged making its removal impossible.

You need to have a perfect fitting screw driver tip. Anything else and you will destroy the slot on the main jet and turn your carb to junk.

I find the screwdriver tip sets which contain many sizes and styles of tips usually has a slot tip that just fits in the slot of the main jet.

If there is any rotational play when you gently rotate the tip, you need a slightly bigger one.

Once you have the proper tip, you keep firm pressure on the screw driver handle as you try and rotate the brass jet.

I think once you have the emulsion tube cleaned, your need to use the choke will disappear.

I don't know the carb on your machine. If my general description does not seem to fit, post some pictures with the float bowl removed.

Dave M7040

 

[Tooljunkie]

I figuring the same, along with water in fuel tank. A stabilizer added to gas during seasonal inactivity will help with this after you get it solved. My off coloured 18 hp briggs was like this too, switched to electric fuel pump. It was a impulse type. Ran great ever since. What started my whole mess was water in the gas tank.

 

[Tommy S]

Thanks for the info all. This afternoon it came to me that the issue was lack of fuel; hence the choke. Everything from the pump to the carb had been cleared and I had taken the carb apart and cleaned it as well.

What was left? Well the line from the tank to the pump. A more detailed look at that line and I found another filter tucked up under the side profile of the tank. After removal of the "firewall" that the pump and filter two are mount on I was able to remove filter #1. It was full of what looks like grass. I will be cleaning the tank out as well.

Tomorrow it gets a new filter #1 and I'll let you know if that was the final problem.

Thanks again for all the input.

 

[Tommy S]

Thank you Dave M7040 for the advice on the carb. I took it back off and completely cleaned it as instructed. When the mower was back together I turned on the key and let the fuel pump come up to pressure. The mower started right up. I let it warm up and backed out. I engaged the blades and started mowing. After about five minutes volumes of grey smoke started coming out of the exhaust pipe. I disengaged the blades and took it to the shop. When the blades were disengaged the smoke stopped.

After it was off I checked the crankcase oil and found it to be about quart over full. It appears that a seal has broken that allows hydraulic oil into the combustion chamber.

I guess that my next stop is the dealer. Any other suggestions?

 

[lugbolt]

I can't think of any way hydraulic oil can get into the engine. I've got one torn apart out in the shop, doing engine work (was run out of oil), but there is zero hydraulic connection to the engine. Just a stub shaft sticking out of the flywheel side of the engine that connects to the transmission's input shaft via a u-joint that rarely gets greased. But nothing else. Are you sure it's not fuel in the crankcase? Seen that a time or two.

 

[Dave_eng]

Thank you Dave M7040 for the advice on the carb. I took it back off and completely cleaned it as instructed. When the mower was back together I turned on the key and let the fuel pump come up to pressure. The mower started right up. I let it warm up and backed out. I engaged the blades and started mowing. After about five minutes volumes of grey smoke started coming out of the exhaust pipe. I disengaged the blades and took it to the shop. When the blades were disengaged the smoke stopped.

After it was off I checked the crankcase oil and found it to be about quart over full. It appears that a seal has broken that allows hydraulic oil into the combustion chamber.

I guess that my next stop is the dealer. Any other suggestions?

I am with Lugbolt on this one.

I would start from the ground up and drain the engine completely of all engine oil.

V-Twin, air-cooled, Kubota 27HP petrol engine

Since the engine is air cooled, no antifreeze is present and getting into the crankcase.

I don't see any direct connection with the hydrostatic wheel units and the engine that would allow fluid from one to flow to the other

Drain the engine and refill using the amount spec's in your owners manual rather than reply on the dipstick. If it says 3 liters with the filter being changed, put 3 liters in along with a new filter.

If you or whomever serviced the engine last put too much oil in, then, as it heats up and starts to foam, the crankcase vent system, which I expect puts crankcase oil fumes back into the engine to be burned, can be putting frothy oil into the air cleaner and carb. Look in your air filter housing for a rubber hose than comes from an upper part of the engine, perhaps a valve cover. This will be the crankcase vent system and if oil is too full it will make its way out this hose and the inside of the air filter will be very messy.

Make certain the crankcase vent system is not plugged.

Dave M7040

 

[rentthis]

Tommy, one problem we have in the rental business is people hauling gas engine machines with the fuel turned on at the engine. Often, this will cause gasoline to get into the engine crankcase. An oil change usually does the trick. If you drain the oil, smell for gasoline in the oil. If the machine sets for a while, gas can turn into shellac in the main jet (item B in Daves post), sometimes it takes a little extra effort to remove it. Any at all is to much.