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Have a 721 gasoline Kubota front deck mower. I think its either 1997 or 1998 model. Only made the gasoline kubota a couple years. My problem is it wants to sputter at times. It seems to do it after the engine is warm more than other times. Most of the time its when I make a turn and then start advancing that it seems to want to stall or sometimes when I am going up a hill and for no reason it sputters. Almost like it doesn't have enough HP in reserve. At other times it seems normal.
Also it does not seem to be affected when blades are not engaged.

Any Thoughts?

My 99 Grasshopper (725 Kubota) was sputtering. I thought it was the plugs fouling, but it needed a new distributor cap & router. It ran great after I changed them.

any other suggestions? It did it again today. I mowed for about 15-20 minutes then it almost dies then starts up again. repeats about every 2-3 minutes. I am going to change spark plugs just to try but also thought it might be coil getting hot and not working correctly
Also after it is stopped and turned off. It is really hard to get started back if it hot

At the gas tank , take the supply line off and twist the dip tube out of the tank see if grass is inside of the tube

JUST4FUN said:

At the gas tank , take the supply line off and twist the dip tube out of the tank see if grass is inside of the tube

Click to expand...

nothing plugging gas unless its in fuel pump. dont know yet
I really think it has something to do with it getting hot.(not too hot just running temp)
It never happens when first cranked and always seems to start after about 15 min of run time
thanks for advice

Update
I have tried cleaning out carb
new spark plugs
new fuel filter and fuel lines
emptied out old gas and made sure dip tube was clear
put in high octane gas
cranked with a boost from charger. I think battery needs to be replaced not holding amps
Checked vent on gas cap and loosened when sputtered but no change.

Runs pretty good for about 15 min. Then when I turn and push levers all the way forward it sputters and almost dies but I can back off and then let motor catch up then it will go as long as I ease levers slowly.
To me, and I am no mechanic, to be starving for gas when its warm and it is being called for by levers or in high grass
I guess it could be flooding but I really dont know how to tell the difference in sound. I really think it starving for gas but IDK

I also checked the resistance in coil and it seemed to be ok except the positive to neg was slightly high but I checked a new one as well and it was close to that.

My grass is getting high and I dont want to have to take to repair shop but I am running out of options.
If anyone has any expertise in this area I sure would appreciate the advice

I'm no mechanic, but like I said before, my mower was sputtering and I changed the distributor cap & router and it ran perfect after that. It's tucked away behind the carb. A Kubota dealer will have the parts.

I guess I didnt want to try that yet since its a bigger deal. I had one go bad before and it was slightly different. It would just cut completely off. The distribitor cap and part underneath was changed about 5-6 years ago at dealer. They had to time it afterwards. Whole thing was about $700 dollars!!!! $450 was in labor best I remember on it
I have no idea how to time one so I would have to take it somwhere

You can do it yourself. Take some pictures before. The carb has to come off, but I think you can leave the linkage hooked to it. There is a small blue metal cover in front of the distributor cap. It's held on by 2 or 3 phillips head screws. I think is was 1 1/2 to 2 hours to replace. It takes long because everything is tucked in a small spot.

I know I can get to it because I did it before when it went bad.. My question is will it need to be timed????? That IDK what to do if it did. If its just pull off distribitor and replace a visible part then I can do that. Someone suggested to me maybe a condensor. I have no idea if it even has one of those. lol

I think the only thing that you have to be careful of , is putting the rotor on the way it came off. It might be "idiot" proof , that it only goes on one way - I can't remember. The cap just snaps on with 2 clips. No timing needed. And of course make sure that the wires go on the correct spots on the cap.

K I may give it a try if I can find the part Monday. No dealer close. Grasshopper dealer hour away not sure about Kubota

When you pull the cap off take a pic so you can put the new one in the same way.

And to not turn the engine over untill the new one is in.

Well this is more like a blog than repair but I hate it when I read forums and no answer ever gets finalized so here is my summary.

I took off carb and distributor cap just to see what if anything looked corroded. I also checked the fuel solenoid with power supply to see if it was responding correctly. While I was doing that the positive terminal broke off of fuel solenoid( not by me but just by moving wire). I repaired by doing some trimming of plastic cover and soldering wire back to solenoid. Also other end of wire broke off. Could tell were it had been arc ing.

I reassembled everything and mowed for about an hour. Looks good so far. I guess I got lucky and found problem. I supose as the mower got hot the metal expanded and made it more difficult to make the connection. I think I am going to pick up a new solenoid just to have on hand if this one degrades any further.

Thanks for every ones advice!

Glad things worked out. Thats for letting us know!

erbowman said:

Have a 721 gasoline Kubota front deck mower. I think its either 1997 or 1998 model. Only made the gasoline kubota a couple years. My problem is it wants to sputter at times. It seems to do it after the engine is warm more than other times. Most of the time its when I make a turn and then start advancing that it seems to want to stall or sometimes when I am going up a hill and for no reason it sputters. Almost like it doesn't have enough HP in reserve. At other times it seems normal.
Also it does not seem to be affected when blades are not engaged.

Any Thoughts?

Click to expand...

Your description makes the governor come to mind. Make sure all the linkage is free.

erbowman said:

Well this is more like a blog than repair but I hate it when I read forums and no answer ever gets finalized so here is my summary.

I took off carb and distributor cap just to see what if anything looked corroded. I also checked the fuel solenoid with power supply to see if it was responding correctly. While I was doing that the positive terminal broke off of fuel solenoid( not by me but just by moving wire). I repaired by doing some trimming of plastic cover and soldering wire back to solenoid. Also other end of wire broke off. Could tell were it had been arc ing.

I reassembled everything and mowed for about an hour. Looks good so far. I guess I got lucky and found problem. I supose as the mower got hot the metal expanded and made it more difficult to make the connection. I think I am going to pick up a new solenoid just to have on hand if this one degrades any further.

Thanks for every ones advice!

Click to expand...

Whoops! Looks like I should have read the whole thread first.

Your experience is more evidence of how valuable a visual inspection can be sometimes.

Water getting in the distributor cap & router !that was my problem my engine would sputter and only would run right if I pulled the choke clean it replace the cap and seal if neeed.

Well wound up having to replace some module and distributor cap. $150 at dealer. Not bad
Have mowed aprox 3 times. Finished mowing yesterday turned off so I could blow dead grass off and weeadeat etc. Probably hour later attempted to crank. Turned over great but does not seem to fire. I bled the carb out a couple times so I know its getting gas, I am going to check all connections and check resistance on coil.

Might need to check fire in spark plugs. Any other suggestions????