Kubota ZD21

[CAH2873]

Hello,
I have a Kubota ZD21 mower. It is 8 years old and I have never had a problem with it until recently. When I get on the mower and start to crank it, sometimes the motor will fire right off and sometimes it will sit there and turn over but never crank. I wait until the glow plug light goes off everytime, but it does seem to have a regular routine. It has been getting worse over the last few months. I contacted the Kubota dealership and they stated it would take 2 -3 weeks before they could look at it. I have too much grass to mow right now and it would be hard to let go of it. Does anyone have any ideas or suggestions to look at and try to diagnose? Thanks for any input.

 

[Ken Cunningham]

If your battery is good and its turning over fast enough to crank, my shot in the dark guess would be low compression.

 

[art]

My thoughts are that you have a fuel problem Kubota engines start, you couldn't have worn it out to the point of lack of compression.

I'd start with changing the fuel filters and check the fuel flow when the filter is removed.

Have you had any signs of loss of power while operating?

 

[Dozernut]

I have to agree with Art, it sounds like a fuel problem, plugged filters or contaminated fuel. Changing the fuel filters is the one of the things you should do. There are two fuel filters on the ZD21. One is in sight above the battery and the other is behind and at the bottom of the back side of the battery, The second is a PITA to remove and replace. You have to pull the battery or jack up and block the mower to allow you to get both hands in to access the filter. While you have this hard to get to filter off, this would be a good time to drain the fuel tank then use an air compressor to pressurize the tank and blow out 8 years of accumulated crud or water from the tank and lines.
Last thing to check is the fuel pump if the aforementioned service did not help. It is the round metallic object between the two filters and bolted to the engine. Pull the fuel line from the output side and crank the engine and see if you have flow. The pump cost $100 so I hope the filters do the the trick for you.

 

[CAH2873]

There are no signs of loosing power while running.

 

[Dozernut]

Rereading your post it sounds like your engine stop solenoid is sticking. Since the diesel does not use spark to ignite the fuel the only way to shut a diesel down is to stop the fuel flow. From what you are describing it sounds like the solenoid is sticking shut. Maybe a bad solenoid or a short in the wiring. It should be located close to the injectors.