Kubota Z781KWI nightmare

[brooster]

Bought this used a couple months ago with 98 hrs on it. First couple of weeks all is good, but then one day while mowing I cut the blades off and the mower start “missing, surging” it would go from 2300 rpms to 1300 and back up again and again. So I changed the fuel filter and plugs, no change. Then it started doing this also when mowing. So far I have checked fuel tank and pickup, clean. Replaced lift pump, fuel line and filter again. Checked spark with an inline light and it appeared I had a miss in one cylinder, so I replaced that coil pack. This was yesterday, took the mower out and again was missing, but when I started mowing it ran great, 2700 rpms for over an hour and never missed a beat, even when done I cut the blades off and seemed to be running fine. And now today took it out to mow a small patch of grass and it was missing worse than ever, blades off or on! The only thing that I haven’t done yet is checking the valves. Is there something that I’m missing? The engine is a Kawasaki FX850V injected not carburetored

 

[Ktrim]

Bought this used a couple months ago with 98 hrs on it. First couple of weeks all is good, but then one day while mowing I cut the blades off and the mower start “missing, surging” it would go from 2300 rpms to 1300 and back up again and again. So I changed the fuel filter and plugs, no change. Then it started doing this also when mowing. So far I have checked fuel tank and pickup, clean. Replaced lift pump, fuel line and filter again. Checked spark with an inline light and it appeared I had a miss in one cylinder, so I replaced that coil pack. This was yesterday, took the mower out and again was missing, but when I started mowing it ran great, 2700 rpms for over an hour and never missed a beat, even when done I cut the blades off and seemed to be running fine. And now today took it out to mow a small patch of grass and it was missing worse than ever, blades off or on! The only thing that I haven’t done yet is checking the valves. Is there something that I’m missing? The engine is a Kawasaki FX850V injected not carburetored

Check the wiring on the voltage regulator. Went through similar issue on my zero. Different model. But found wire shorting on regulator causing spitting sputtering misfire.

 

[brooster]

Check the wiring on the voltage regulator. Went through similar issue on my zero. Different model. But found wire shorting on regulator causing spitting sputtering misfire.

Will do thx

 

[brooster]

Checked out the wires from the voltage regulator and what I could see in the harness and did not see any damage, even moved wires around while running. It was surging the whole time and no change while moving them. I do appreciate the suggestion, thx

 

[Ktrim]

Checked out the wires from the voltage regulator and what I could see in the harness and did not see any damage, even moved wires around while running. It was surging the whole time and no change while moving them. I do appreciate the suggestion, thx

Welcome. It was worth a shot. It drove me nuts for several weeks. Good luck

 

[GreensvilleJay]

sigh, googled Kawasaki FX850V injected , 1st hit the kawi.eu site info.. NOWHERE does it say it's a gas engine ! ( I was looking for the sparkplug info.....)_

so... did you replace BOTH sparkplugs with whatever kawi says they should be ?

'surging' to mean say 'governor' needs adjustment . maybe the surge spring is missing or broken ??

 

[Outnumbered]

I had it happen on the Kawasaki engine on my zero turn and it turned out to be to of the welch plugs on the carburetor had come out. A few bucks and some nail polish to seal in the replacements and no more issues for the last few hundred hours.

 

[brooster]

sigh, googled Kawasaki FX850V injected , 1st hit the kawi.eu site info.. NOWHERE does it say it's a gas engine ! ( I was looking for the sparkplug info.....)_

so... did you replace BOTH sparkplugs with whatever kawi says they should be ?

'surging' to mean say 'governor' needs adjustment . maybe the surge spring is missing or broken ??

Yes, both plugs, twice, adjusted the valves, new fuel filter, new fuel pump, air filters, one ignition coil(waiting on the other), the only other thing I can think of is the voltage regulator, this morning it threw a code of PO563

 

[brooster]

I had it happen on the Kawasaki engine on my zero turn and it turned out to be to of the welch plugs on the carburetor had come out. A few bucks and some nail polish to seal in the replacements and no more issues for the last few hundred hours.

This one is fuel injected