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I bought this ZTR 10yrs ago (less than 400hrs) and it's run great until this spring. Recently it will run fine for about an hour at full throttle(~3,000rpm) then sputters and dies. If I let it sit overnight it will do the same thing the next day. If I run it at 2,600rpms it will run longer but still dies after about 1.5hrs. I can sometimes keep it running with the choke but it still wants to die after about 2hrs. If I disengage the blades when it begins to stutter it will often resume running normally without dying. I have replaced the fuel and air filters and checked the fuel line. And the last 2 wks it has started to smoke (blue) when I start it I change oil regularly.

Any ideas?

That has the signs of a failing ignition coil when hot. Just the same, a spark plug could also be breaking down and plugs are easy to replace.

When it acts up, use a spray bottle to shoot a stream of water on each exhaust pipe near the cylinder head. The water should burn off quickly if the cylinder is working, if the water does not burn off quickly, that would be the cylinder with an ignition spark plug or coil failing.

Use only a genuine Kawasaki branded coil (If it is the coil failing). Amazon coils are junk right out of the box in most cases. The same goes with spark plugs, get them from a local parts store and make sure the numbers match. Don't except the "it will fit" story when it comes to spark plugs. Spark plugs have different heat ranges that will affect the running performance.

Thanks for the info Doc. I forgot to mention that I just changed plugs. I never thought of the coils. I've had that problem on my tractor. I'll run the engine this evening when I get home and see if the problem is a coil. Thanks again.

Did the coil change solve the problem?

My apologies for not responding sooner. My 99yo WWII veteran father passed away and it’s been a rough time around here. Unsolicited advice: put your affairs in order; your heirs will thank you. Anyway, I need a distraction now.

To address Doc’s suggestion, I mowed until it stopped and check the exhaust; both cylinders were working fine. The exhausts were steaming hot. I have recently changed plugs and both filters.

To recap, the symptoms are:

• Stops running after about an hour. It just sputters a little and stops.
• Sometimes I can keep it running with the choke, but I don’t like to do that.
• Disengaging the deck when it starts sputtering sometimes keeps it running a few minutes but it
• I can mow longer if I run at lower RPMs, 2600 tops.
• Sometimes it puffs a little smoke when I first start it, blue smoke (yikes!).
• Today it would only run about 20 minutes, and it ran rough. And I could not keep it running with the choke.
• I have kept very good care of this machine. Changed oil, filters, and plugs per manual, blow it off after every use, and it stays inside every night. It has about 400hrs. Kawasaki FR651V.

NormanB said:

My apologies for not responding sooner. My 99yo WWII veteran father passed away and it’s been a rough time around here. Unsolicited advice: put your affairs in order; your heirs will thank you. Anyway, I need a distraction now.

To address Doc’s suggestion, I mowed until it stopped and check the exhaust; both cylinders were working fine. The exhausts were steaming hot. I have recently changed plugs and both filters.

To recap, the symptoms are:

• Stops running after about an hour. It just sputters a little and stops.
• Sometimes I can keep it running with the choke, but I don’t like to do that.
• Disengaging the deck when it starts sputtering sometimes keeps it running a few minutes but it
• I can mow longer if I run at lower RPMs, 2600 tops.
• Sometimes it puffs a little smoke when I first start it, blue smoke (yikes!).
• Today it would only run about 20 minutes, and it ran rough. And I could not keep it running with the choke.
• I have kept very good care of this machine. Changed oil, filters, and plugs per manual, blow it off after every use, and it stays inside every night. It has about 400hrs. Kawasaki FR651V.

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Hi Norman B,

Sorry for your loss. I am a Veteran, and it is always difficult.

As for your mower problem, this is a classic sign of trash in the fuel tank getting sucked in until fuel is starved down. If you can run it with the choke for a little longer that is also a sign of fuel starvation.

Give use your product label information so we can better reference the design and parts layout.

Kawasaki FR651V
Kubota Z122R

Thanks NormanB,

That is the engine info, thanks for that, but Kubota does not build the engine.

What about the product label mounted on the mower chassis? That is what is needed to look up the design layout of the chassis and fuel supply system.

Fuel was my first guess so I replaced the fuel filter and pulled the line from the tank and checked it for obstruction. In the attached pic you can trace the fuel line from the tank to the pump. From there it goes straight to the carb.

I think I may have solved the problem. While having a sandwich I was going over all the symptoms/clues in my head. Starts fine when I first get on it. I always start with a full tank to begin with. Runs about an hour at 2600rpms (3100 is full rabbit). Then it sputters and stops. Sometimes I can get it to run a little longer with the choke, but it doesn't run great. Yesterday it stopped after about an hour and limped it back to the garage. This morning I tried starting it (without filling the tank) and no go. It would start, sputter, and die immediately. So I went to doing other things. This afternoon it dawned on me, maybe it only runs on a full, or mostly full tank (I'm embarrassed for not thinking of this sooner). An hour of running takes it down to just over half a tank. So I went out, topped off the tank, and it started right up and ran great while I finished mowing. I'm thinking I have a weak fuel pump, though I don't know much about these type of pumps. The pump sits higher than the tank, and as the fuel level drops the pump has to work harder to retrieve the fuel. At some point it just can't retrieve any fuel and dies.

Does sound logical?

Hi NormanB,

That is rational. Verify the actual pump pulse vacuum line is not loose, cracked or split.

The extra fuel means more weight in the tank so the fuel will feed easier to the carburetor. When the fuel gets low, the pump has to work harder. If the vacuum pulse line is cracked or the pump is bad, the pump will not work efficiently.

These pumps are a simple crankcase diaphragm pulse pump on most models.

Thanks for the info Doc. I'll check out the vacuum pulse line tomorrow.