SOLVED: Kommander ZT Fuel Problems, sputtering, stalling, etc.

[grumpyoldmansmith]

Everyone,

Sharing this public service announcement for what it's worth as my local dealer says they've seen it on a number of the Kommander ZT's.

I have a 2013 ZG124E with a 48" deck. Last fall for no apparent reason I could think of, it started stalling & running rough. Like it couldn't get enough fuel. It would run okay for 5-10 under PTO load after I started and would stall. After that, I couldn't keep it going for more than several seconds. When I came back to it the next weekend, same thing.

I tried:

• Cleaning the carb
• Adding Dry Gas
• Replacing the fuel filter
• Replacing the air filter
• Checking the plugs

All with no luck. After a conversation with the service guy at my Kubota dealer, he said it was likely tube mechanism going into the gas tank. There is a 90 degree bend which apparently allows debris (grass) to get stuck, limiting fuel flow. After it sits for 10 minutes or an hour or a day, gravity pulls the debris back into the tank where the cycle can start all over. How debris is getting in there is a mystery.

The fix is a new tube to insert into the gas tank which has a mesh screen on it. Cost me $18.

Took literally 2 minutes to install and the first time I started it, it ran as strong as ever.

Hope this saves some of you some time, money and headache!

I had the same issue last year and replaced with the new screen. Literally the easiest fit ever.

 

[Bdiamond]

I just bought a z411-48 back in March. Having same problem since new and now has 10 hours. Full throttle in PTO and rpms drop like the engine is starving for fuel. Happens for a few minutes in beginning and then runs fine. I took out the pick up tube which had a screen, disconnected from fuel filter and blew into fuel line to clear, if any blockage. Ran mower and same thing occurs. I’m at a lost and there are no Kubota dealers within 150miles from me for warranty repairs.

 

[lugbolt]

I just bought a z411-48 back in March. Having same problem since new and now has 10 hours. Full throttle in PTO and rpms drop like the engine is starving for fuel. Happens for a few minutes in beginning and then runs fine. I took out the pick up tube which had a screen, disconnected from fuel filter and blew into fuel line to clear, if any blockage. Ran mower and same thing occurs. I’m at a lost and there are no Kubota dealers within 150miles from me for warranty repairs.

pull the choke lever up when it's acting up. If it picks up power and runs normally with the choke pulled, then you have a fuel starvation issue. If it doesn't, you could have anything from one fouled spark plug, cylinder misfire, internal engine problem, etc.

 

[pritcharddesign]

My Kubota dealer told me about this tube (new one with screen is on backorder) but I couldn't find it on the mower.
Can anyone share a photo or digram?
Thank you!

 

[DonG]

I have fought this problem with Kubota Z725 with the Kohler 25 hp Command Pro. Tried everything suggested including replacing the ignition coils with Kohler MDI conversion kit. I finally tracked down the issue and solved the problem with my machine. The Mensa candidate at Kubota who designed the placement of the muffler directly beneath the fuel lines feeding the carburetor didn't realize they were creating a vapor lock when the machine gets hot especially on a hot day in August. I think it doesn't manifest itself until there are about 200 hrs on the machine because this is when the original fuel lines start to degrade from the heat. I installed a three port fuel filter with a return line tied to the existing return line at the front of the gas tank (third return line port on the filter installed at the 12 o'clock position). I also positioned a piece of cement board between the muffler and fuel lines feeding the carb. Not pretty but it works. No more vapor lock. Thanks to Kubota for all the headaches and no solutions when I ask for answers.

 

[TJFrees]

I have fought this problem with Kubota Z725 with the Kohler 25 hp Command Pro. Tried everything suggested including replacing the ignition coils with Kohler MDI conversion kit. I finally tracked down the issue and solved the problem with my machine. The Mensa candidate at Kubota who designed the placement of the muffler directly beneath the fuel lines feeding the carburetor didn't realize they were creating a vapor lock when the machine gets hot especially on a hot day in August. I think it doesn't manifest itself until there are about 200 hrs on the machine because this is when the original fuel lines start to degrade from the heat. I installed a three port fuel filter with a return line tied to the existing return line at the front of the gas tank (third return line port on the filter installed at the 12 o'clock position). I also positioned a piece of cement board between the muffler and fuel lines feeding the carb. Not pretty but it works. No more vapor lock. Thanks to Kubota for all the headaches and no solutions when I ask for answers.

DonG, I also have a Kubota Z725 doing the same thing and would like to duplicate your actions to see if it fixes my problem as well. I am not sure I follow what line you are referring to as the "return line at the front of the gas tank." Would you mind sending a picture of your fix so I can try it on mine? A picture of your three port filter showing which port you routed to the return line would also be fantastic. Thanks for your comment, it is giving me hope with a problem I have been fighting for a while!

 

[StarTech]

I have fought this problem with Kubota Z725 with the Kohler 25 hp Command Pro. Tried everything suggested including replacing the ignition coils with Kohler MDI conversion kit. I finally tracked down the issue and solved the problem with my machine. The Mensa candidate at Kubota who designed the placement of the muffler directly beneath the fuel lines feeding the carburetor didn't realize they were creating a vapor lock when the machine gets hot especially on a hot day in August. I think it doesn't manifest itself until there are about 200 hrs on the machine because this is when the original fuel lines start to degrade from the heat. I installed a three port fuel filter with a return line tied to the existing return line at the front of the gas tank (third return line port on the filter installed at the 12 o'clock position). I also positioned a piece of cement board between the muffler and fuel lines feeding the carb. Not pretty but it works. No more vapor lock. Thanks to Kubota for all the headaches and no solutions when I ask for answers.

And when our gas distributors switch Winter fuels to Summer fuels early doesn't help. I had a Briggs and a Kohler both having vapor lock problems a few years ago because of this. The fuel actually was bubbling in the clear fuel filters. Insulated the fuel lines and solved that problem. Took a hint from a JD that I was working on that JD had insulated the fuel lines on from the factory.