Huh????
I have same unit at 227 hours, just put grapple on used it without issue. Since these tractors have an electronic throttle and also an electronic kill solenoid it could be either is going bad or connections are loose. Regardless you should have some warranty left for dealer to repair at no cost. If you have ruled out fuel and filter then it has to be something else. I have had in the past electric pto switch go bad causing no start on zero turn mower. I know there is circuit passes through for safety. Doubtful it’s your seat switch as the MT225S will start and run without occupant. Now it could be your safety switch on the seat, if no weight is on seat and hydrostatic drive is engaged tractor will die. Previous threads you mentioned backhoe on tractor meaning you have positional seat. Inspect switch check continuity disconnected this might be your issue. Regardless you have warranty coverage.
I must come under the wire only kill switch I have on my MT225S is if the hydrostatic engages without my bottom side on it the tractor dies. I can start unit without being on the seat. Same goes for pto switch unless you’re in the seat it dies. I am at 280 hours no issues except had to rebuild the mmm mower wheels. Mounted cage bearings on swivels and inserted steel bushings in plastic wheels. Lastly drilled the bolts through to add grease zerk for lubrication of steel bushings. Not planning on working on the wheels again for 300-500 hours. Has anyone changed out hydrostatic fluid needed to know if unit is self priming some require positive pressure to get oil to the pump.
