V2203di Generator RPM Issues

[RAhr24]

First post here. I know its not a tractor, but its a kubota diesel generator which probably has some similarities in general to operations. I have a V2203DI kubota with a variable 50/60hz generator. When working correctly, they run at 50hz (1500rpm) in low load operator and 60hz (1800rpm) in high load. One of the ones I'm working on starts up at 60hz no matter what. It has a voltage controller that provides a signal to the electronic governor. Normally if one of those is bad, it will run at 50hz no matter, so I know thats not the issue (switched it out just to make sure). There is an engine speed sensor that sends signal to the the EG, checked the pins on that into the EG and they have continuity, also replaced the speed sensor just to verify its working correctly, still starts up at 60hz. Switched out the EG with one from a unit that is working correctly, same problem exist.

One thing I do not quite understand is how these electronic governors work with the speed sensor and the mechanical injection pump. How do they get the signal and regulate the fuel on the injection pump? I haven't taken out these injection pumps before to look at the internal mechanical governor (fuel solenoid too). Maybe somebody could help me explain how these work as I figured most basic diesel generators work close to the same. I'm guessing that the mechanical governor or pump has an issue? Any help would be greatly appreciated.

 

[Motion]

Not sure if this will help, but most generators speed sensors that are mounted so as to count pluses from crankshaft i.e. the starter ring gear, the pluses are sent to a electronic control unit which sends a signal to the governor actuator which in turn increases or decreases the throttle to maintain the desired RPM which produces the Hertz (cycles), which setting (50/60) was fed into the electronic control unit. Those three components only job is to maintain a fixed RPM regardless of load. Normally the sensitivity is adjustable to quickly pickup/unload. Try to verify what signal is being given to the voltage controller or what I'm calling a electronic control unit. There should be on your control panel frequency knob/switch, ensure that the wiring from it to the controller are OK. Good luck

 

[RAhr24]

Not sure if this will help, but most generators speed sensors that are mounted so as to count pluses from crankshaft i.e. the starter ring gear, the pluses are sent to a electronic control unit which sends a signal to the governor actuator which in turn increases or decreases the throttle to maintain the desired RPM which produces the Hertz (cycles), which setting (50/60) was fed into the electronic control unit. Those three components only job is to maintain a fixed RPM regardless of load. Normally the sensitivity is adjustable to quickly pickup/unload. Try to verify what signal is being given to the voltage controller or what I'm calling a electronic control unit. There should be on your control panel frequency knob/switch, ensure that the wiring from it to the controller are OK. Good luck

Just from reading, I understand that the speed sensor signal is compared to the governor set point and on most engines, it adjusts some actuator on the fuel rack to compensate for load. This engine doesn't have an actuator, just the fuel stop solenoid. That's just a plunger that retracts when it gets 12 volt signal during operation. Now, if I unplug the voltage controller, these engines run at 50hz, I know that for a fact. When I do that, that takes the generator out of the equation so it has to be an engine speed problem. If the speed sensor is fine, the electronic governor is fine, then it should be a mechanical governor/injection pump problem right?

Here is a photo of the pump. You see the two sensors on it. Speed sensor on the bottom and the fuel shut off solenoid to the right of it. What does an electronic governor do without an actuator?? I can only think that maybe the gap between the speed sensor and whatever its reading is more than it should be, or the governor is messed up somehow.

Curious, if somebody adjust the screws on the control plate, how does that effect rpm during startup and running? Will the governor compensate for that?

Sorry, for all the questions, just trying to get a grasp on how all this stuff fits together.

 

[Motion]

You may try Goggling the model and see any manuals are available. When defaulting to 50hz. are you running various loads? Something needs to be varying the governor.

 

[RAhr24]

I have the manuals, they suck lol. It says for overspeed conditions, the engine speed sensor or mechanical engine problem is the issue.

How the heck does an engine speed sensor and EG change the speed of the engine though without any mechanical linkage that I can see? Makes no sense to me.

 

[Motion]

How many KW is the generator? Do you have a load bank, if so hook and see how the engine reacts when you put in bind.

 

[RAhr24]

I didn't know but the missing variable in all this was the shut off solenoid. It doesn't just shut off the fuel, it gets a varying voltage signal from the electronic governor (which compares rpm from the set parameter with the speed sensor) to compensate for load. The shut-off solenoid is the actuator. Learn something new everyday. Was worn out and sticking a bit.