ZD 331 -

[cptcrnch]

ZD 331 - Bogs down in LOW grass

Hi guys,
new to the forum and fairly new to Kubota Zero Turns.
I have a 2012 ZD331 zero turn diesel
2nd season I've used this to cut about 5 acres of grass on a rural property.

Recently, I've had an issue where the engine seems to bog down at slow speeds like its in deep grass, when its not. It seems like it wants to stall but usually doesn't.
It happened 8x in a 4 hour cutting session over the w/e.

This situation seems to almost stall the engine, however it seems to be the blades that are slowing down NOT the engine (if that makes sense).
If I disengage the blades that helps it to recover, however it seems from what I can tell from the engine, when I disengage the blades the engine rpm are still high....meaning the engine rpm were not bogged down, they are still humming right along
It seems to be at fairly slow speeds when the drive handles are slightly pushed in the forward position.
Pushing the handles forward does NOT change the bog down situation much....very slight. i can usually recover the blade speed if I pull back on the handles and/or disengage the blades for a few moments. then when I reengage
the blades I'm good and cut again.

Its very intermittent. It happens going up a hill or down a hill or on flat ground. I can not reproduce the symptoms at any time...its random. I've changed the air filter and both fuel filters.
I'm stumped.
Could it have something to do with a belt driving the blades slipping? is there a way to tell if belt is going bad and may be the culprit?
Is there a sensor on the handles that could be problematic?

I haven't had much luck on the internet regarding this issue and a ZD331.

Any help or direction is much appreciate.
Thanks!
JR

 

[mechanic mark]

Take to Kubota shop for maintenance & repairs.

 

[cpurvis]

When was the last time the fuel filter(s) were changed? Does it have a restriction indicator on the air filter? If so, what's it reading? If not, when was the last time it was replaced?

 

[jekjr]

I had serious issues earlier this year with algae in my fuel. Filters did not catch it either. Had to get pumps flushed out. I highly recommend using an algae preventer in modern low sulphur fuel. This problem didn’t exist with older high sulphur fuel.

 

[bertsmobile1]

Recently, I've had an issue where the engine seems to bog down at slow speeds like its in deep grass, when its not. It seems like it wants to stall but usually doesn't.
It happened 8x in a 4 hour cutting session over the w/e.

May be just grammar but are you saying it bogs when the engine is running slow ?
Diesel engines have a very limited rev range unless they have a much more complicated EEM system than found on mowers

 

[lugbolt]

change BOTH fuel filters (first!).

If that solves it great. If not, do a fuel flow test. Remove fuel line from the injection pump (the rubber line that comes from the filter) and put the end in a jar. Turn the key on, should get nice steady flow. I like to leave it on for a few seconds enough to almost fill the jar. Flow should not slow down. If it does, there is a possibility of junk in the fuel system somewhere, which could be at the fuel valve, lines, filter(s), or inside one of the fuel tanks. Or perhaps a failing electric fuel pump. When the electric pump goes dead, normally they'll get hot to the touch but not always.

If fuel flow test is ok, there are 3 filters on the hydraulic system. One is a screen in the bottom of the transmission case, the other two are spin-on filters. If that screen gets plugged (and they do), it'll cause issues starting with the PTO clutch and then later on the hydraulic deck lift will get slower, then you'll get HST noises and finally it just stops pulling. Usually-but not always-in that order. Most people forget about that screen and it never gets cleaned. On the bottom of the case, there's a large metal pipe that has a "bolt" that holds it into the case; the screen is built into that bolt. When you remove it, you will lose all the fluid from the transmission so be prepared for lots of fluid loss (drain it first), and then I'd also suggest replacing both spin-on filters if you haven't already, then of course refill with Super UDT2.

If all that is ok, you might want to invest in a work shop manual and some tools. Or pay the dealer, BUT intermittent issues are TOUGH to isolate even for a dealer. That means it takes time, time=labor and that means $$$ to you.