I have a 1998 Case 9020B excavator. The motor that turns up and down the fuel keeps going around and around. In other words the engine reves up and then slows down and keeps doing that. When I bought the machine the owner had the unit unplugged and moved the throttle by hand. I had several electrical issues, but have some of them fixed. The machine came with no fuel shut off, he said he was going to run a choke cable to it and shut the fuel off manually. That may have something to do with it. I am not an electrician or mechanic. Does anyone have any suggestions?
Not sure that I follow you. Are you saying that the engine idle is erratic? Does the engine hold a steady rpm when it's off idle (using the hand throttle)? Have you tried changing the fuel filter(s)?
thank you for responding. You are the only one to respond, I was about to give up. Since I posted my problem I have found and fixed several things. I am finding most of my problems to be electrical. I found 1 blown diode and another not connected. I think the fuel problem is also electrical, but not sure. Yes, I did change the fuel filters. Case has a fuel override button in the cab beside the seat. If I push the fuel override button and move the fuel up and down with the arrows it works fine. If I do not use the override button the fuel surges and then slows down. If I understand it correctly, when I turn the key to th on position (not satrt) the gear box that controls the speed of the engine should go up then down and go to the position the hand throttle is set on. But it does not, it goes around and around and does not stop. So that is making the engine surge then slow down. I hope this makes sense. I can start the machine with the key but cannot control the fuel speed with the hand throttle.
Well, since the fuel is controlled by the injection pump and the fuel override control seems to give a steady state rpm, I would look at the throttle control electronics/connections, etc. I don't know much about troubleshooting these systems but that is where I would look. Maybe someone with more related experience can chime in...
Andy, any progress with the machine?
I work on a Case 9040B which had a similar problem some time ago and it turned out to be a worn throttle control.
My 9030b had a similar issue i had a case auto electrician do a fuel pump rewire and computer reseet and good to go.
Hi, Did you ever manage to sort out the machine, i have a case 9040B which is giving me the same problem, engine revs up and down on its own, any help?