I have a Grasshopper zero turn mower with a Kubota 25 HP diesel engine. I'm finding that through the past couple months I am having to push the throttle up to get it to start. It is getting worse as mowing season goes on. Right now I'm having to go to nearly half way throttle before it will start. Once it starts I can pull it all the way back down for a smooth idle. Engine runs great once started. I've changed all fuel and air filters. Fuel is fresh and clean. I'm running the same fuel in my tractor with no issues. It does have glow plugs and I do use them. I'm assuming they are working. Not sure how to tell. There is a substantial amount of black smoke that rolls out when it starts with throttle up. I'm thinking fuel issue but not sure how to diagnose.
Any suggestions appreciated.
Any suggestions appreciated.