Also, make sure you are adding some Power Services or other Lubricity additave to your fuel, these older diesels and thier pumps do not like this new fuel at all. Even the offroad stuff here is ULSD and Kubota even is saying to use lubricity and cetane boosters on thier diesels. You can take the injectors out and have them "POP" tested at any good diesel injection shop to check thier pop off pressure and spray pattern. A worn injector or pump will show once warmed up, as they get warmer, they loose thier ablity to make proper injection pressure. Usualy a worn injector will cause the engine to have a louder than normal diesel "knock" to it. If you pull the injectors to get tested, run a compression test to see how healthy the rings are, I think the pressure should be a min of around 355psi and the top end was around 450psi by the kubota book, dont have it in front of me at the moment, its back at the shop. Mike