Grasshopper 725 G2. Kubota gas engine problem.

[AMBMike]

Our faithful Grasshopper 725 G2 with the Kubota gas engine is experiencing a problem.

While running it will randomly almost die, seemingly from lack of fuel. It seldom actually dies. It may go 2-3 hours without a problem then act up every minute or less for half an hour or anything in between.
It starts with no problem.

Things I've done.
1. Checked that the fuel pickup tube is not obstructed and made sure nothing but gas is in the tank.
2. Replaced the electric fuel pump.
3. Replaced the carb.
4. Made sure air filters are clean. Actually replaced them with new.
5. Checked all fuses, relays, and wiring harnesses.
6. Checked all safety switches.

Has anyone else experienced this?

Any ideas for me?

Thanks.

 

[mowingman]

Is the tank venting properly? This can cause exactly the problem you are describing. Try running it with the gas cap loose, or take the gas cap off for a while. You may want to somehow tape a piece of window screen across the opening, so dirt does not get in it, if you go this route for testing.

 

[Mr. Wrench]

Have you did anything to the ignition system? You need to determine if it has a fuel or ignition problem. When it is messing up, put a spark checker on the plug wires and make sure that the ignition is not dropping out on any of the plugs. It should be electronic ignition but it will have a distributor cap and rotor. Spray carburetor cleaner into the intake when it is messing up, and if it straightens out you have a fuel delivery problem.

 

[materthegreater]

Solution: remove gas engine and replace with diesel engine. Problem solved.

Joking aside, try replacing the fuel lines. Sometimes they can delaminate on the inside which can cause temporary blockage.

 

[Tyler d4c]

Check the ingnition the electronicsstart to die in them any diesel from a d600 to a d902 will moreless bolt in

 

[HarleyHappy]

New gas?
Maybe running a little Seafoam through it?
Have seen where the intake valve rockers loosen up, restricting fuel to the intake.

 

[AMBMike]

Finally getting back to this.

I replaced the ignition system from the rotor to the plugs, including a new coil. It starts quicker than it ever has now but it did nothing to correct the problem. I pulled the fuel cap while running also and that made no difference.
I'll try replacing the fuel lines next.

 

[HarleyHappy]

There should be a fuel safety valve on the bottom of the carb, that acts like a fuel shut off solenoid. Wondering if it has one, is it heating up and cutting fuel off.
Not that familiar with Kubota gas jobs but most newer engines have this solenoid valve. It’s usually on the bottom of the carb but have seen them in odd, hard to get areas.

 

[Tyler d4c]

There should be a fuel safety valve on the bottom of the carb, that acts like a fuel shut off solenoid. Wondering if it has one, is it heating up and cutting fuel off.
Not that familiar with Kubota gas jobs but most newer engines have this solenoid valve. It’s usually on the bottom of the carb but have seen them in odd, hard to get areas.

The kubota gasser do have this. Ive seen the electrinic pickup or what ever there called go and they get hot do this.

 

[AMBMike]

It does indeed have the valve on the bottom of the carb.

I may have to break out my scope meter and check it out while running.

 

[MG84]

I too would suggest looking into the fuel shut-off solenoid. They can be problematic and cause a whole host of unusual issues. I recently went round and round with one on the 25hp Kohler on my new sawmill, only 14hrs and it started failing, why I do not know. I do know they are very susceptible to fuel problems and our gas (even ethanol free) just keeps getting worse and worse.

Also curious about your Grasshopper mower. Don't think I've ever seen one with a Kubota gas engine, what year model is it? We've had a '92 614, '02 725K and a '25 725K, I absolutely love the front mount Grasshoppers. IMO they are the Cadillac of zero turn mowers, with the low pressure tire and wide axle tail wheel options they are the smoothest riding zero turns out there.

 

[materthegreater]

I too would suggest looking into the fuel shut-off solenoid. They can be problematic and cause a whole host of unusual issues. I recently went round and round with one on the 25hp Kohler on my new sawmill, only 14hrs and it started failing, why I do not know. I do know they are very susceptible to fuel problems and our gas (even ethanol free) just keeps getting worse and worse.

Also curious about your Grasshopper mower. Don't think I've ever seen one with a Kubota gas engine, what year model is it? We've had a '92 614, '02 725K and a '25 725K, I absolutely love the front mount Grasshoppers. IMO they are the Cadillac of zero turn mowers, with the low pressure tire and wide axle tail wheel options they are the smoothest riding zero turns out there.

Kohler engines aren't the best quality in my experience. The Kubota gas engine is probably much better. I had a '91 720K with a Kohler.

 

[mowingman]

Kohler engines aren't the best quality in my experience. The Kubota gas engine is probably much better. I had a '91 720K with a Kohler.

You are correct about that. As a former Grasshopper dealer, I can tell you that the Kubota gas engine can last as long as 7000 hours, if well maintained. A good quality Kohler is about a 2000-3000 hr engine, at best. Kohler also produces a lot of low quality homeowner type engines that are only rated to last about 1000 hrs.
Köhler has sold their engine division to some big investment company. Dealers and mechanics say their quality, over all, is on a downward trend. If so, I think you will begin to see Grasshopper using more Kawasaki engines.

 

[LegdocII]

In a previous life I had a similar situation with a borrowed old Ford 8N. It would run, it would sputter and die. After a minute it would start and repeat the symptoms. Ultimately I found a large wasp stinger with the barb pointing toward the fuel bowl obstructing the orifice.