RT 40 with Kubota engine stalls

[Bacon]

When pushing forward the motor acts as though the hydraulics are lugging down the motor to the point of killing the motor. Letting up on the joystick allows the motor to recover instantly and track moves and pushes a load. Then after a impermanent time the same thing will happen. It occurs mostly with the drive motors but can also happen with the lift function of the loader. When it first showed up it mostly went away for 500 hours or more of operation. Now the occurrence happens so often that the machine is not usable. The machine runs very smooth at idle and full throttle until the stalling of the motor occurs. The stalling occurs at medium rpm and at full throttle. The recovery from the stall is immediate after letting up on the joystick. The next stalling does not occur immediately after again engaging the joystick. The next stall may occur withing a few minutes of pushing or it can be 10 minutes later. In the past it could be days between the stalling behavior. The time intervals are getting shorter after reengaging the joystick to the point that the machine is not usable. Fuel filters have been replaced recently. The fuel priming pump is part of the filter housing and it functions and appears to hold pressure. One Bobcat forum had a member with a similar issue and after years of trying to solve the problem resolved by adjusting his governor. My question is whether this sounds more likely a hydraulic issue with the pilot valve or a fuel issue. I am thinking that maybe the fuel pickup line from the tank is partially plugged and has become more clogged and now restricts the flow when the machine is moving. If it is a hydraulic issue it is probably the solenoids in the pilot valve manifold.

 

[Bacon]

Solved the problem, it was the main fuel filter that probably gelled up due to the cold weather.

 

[foton]

there is some recient posts about fuel conditioners ,when winterised fuel is not in fuel system and additives are needed,some videos too. It seems most work just some better than others. I think hot shot was the best,power service was ok.