D950 Erratic and Hard to Start - Injector Pump?

[Markw]

I have a Kubota D950 on a Jacobson Turfcat, with approx 1800 hours on it. Engine has been dropping on power for a few months. When cranking, it just doesn't smoke like it used to, so seems like its not getting enough fuel. At this point, I'm thinking clogged injectors, or something is going wrong with the injector pump. Maybe air getting sucked in the line somewhere? If I can get it started, it runs for a little bit and then dies. Also, at half throttle, speed varies up and down some. Throttle response is not there. When I bleed the lines, I just don't see it pulsing out like it should. Are all these symptoms of the injector pump going bad?

 

[85Hokie]

have you changed fuel filters???

 

[Russell King]

Check how well the fuel is flowing from the line into the injection pump. Sounds like a blockage somewhere in the fuel delivery line.

Could be just about anything like rust, plastic in tank, biological growth….

 

[JerryMT]

I have a Kubota D950 on a Jacobson Turfcat, with approx 1800 hours on it. Engine has been dropping on power for a few months. When cranking, it just doesn't smoke like it used to, so seems like its not getting enough fuel. At this point, I'm thinking clogged injectors, or something is going wrong with the injector pump. Maybe air getting sucked in the line somewhere? If I can get it started, it runs for a little bit and then dies. Also, at half throttle, speed varies up and down some. Throttle response is not there. When I bleed the lines, I just don't see it pulsing out like it should. Are all these symptoms of the injector pump going bad?

Sounds like a classic case of restricted fuel delivery. Crud in the tank, plugged fuel filter, water in the fuel, failed lift pump (if it has one). Start at the las line before the injector pump (IP), turn on the key and crank the engine holding a container to catch the fuel. You should see a steady full stream of fuel coming out of the line. If it dribbles or is intermittent, then work your way back to the tank checking the flow at the lift pump, before and after the filter, and the tank outlet itself. Chances are it's not the IP. Some times crud gets caught in the filter head casting and so the flow is restricted even with a new filter. Usually there is a strainer in the tank bottom and that can get clogged.

These Kubota's all seem to have different fuel delivery systems, so maybe you have some other components that i haven't mentioned or you may have less. The objective of your trouble shooting is to deliver clean steady, and full flow to the IP.

 

[North Idaho Wolfman]

Lift pump failure could also be an issue.

 

[Markw]

Lift pump failure could also be an issue.

At first I was suspecting the lift pump, so I bypassed it and installed a small electric fuel pump. I tested it by running the pump with line disconnected at injector pump, fuel flows out well, so this eliminates questions about fuel delivery between the tank and the injector pump,

Pump I used is similar to: