Unresponsive thottle motor

[looneytunes]

I got a 2800 Quantum link belt trackhoe with about 7600 hrs on it and sometimes its wide open when its cranked. Thats with the dial at idle in the cab. Can kill it immediately and crank it back up and its at a idle like it should be. Sometimes will be working it and all the sudden itll go to a idle with no response out of the dial. Might have to kill it a couple time before it will throttle back up and work normally. Have checked the wiring at the throttle motor and seems to be okay. Does anyone know whats going on here. Any input would be appreciated.

 

[Simon C]

I got a 2800 Quantum link belt trackhoe with about 7600 hrs on it and sometimes its wide open when its cranked. Thats with the dial at idle in the cab. Can kill it immediately and crank it back up and its at a idle like it should be. Sometimes will be working it and all the sudden itll go to a idle with no response out of the dial. Might have to kill it a couple time before it will throttle back up and work normally. Have checked the wiring at the throttle motor and seems to be okay. Does anyone know whats going on here. Any input would be appreciated.

Could a crank shaft speed sensor be causing problems. Sometimes the computer has a hard time to determine if it needs to speed up the engine or slow down. Sometimes It is a sensor or harness that is damaged. Some times the rotary dial can be faulty and sending the wrong resistance reading to the computer. Maybe start by checking the rotary dial for smooth resistance change with an analog meter to see if it flat spots or does funky stuff. Simon

 

[looneytunes]

Okay Simon i appreciate the info. Ill start with the dial. Hopefully its somethimg simple but my luck it wont be. Ill keep ya posted. Thanks again.. Jeff

 

[Simon C]

Okay Simon i appreciate the info. Ill start with the dial. Hopefully its somethimg simple but my luck it wont be. Ill keep ya posted. Thanks again.. Jeff

The reason I said an analog meter with needle, is that it takes power to cause the needle to deflect as you rotate the switch of course with the switch unplugged and in hand. That way if there is a weak spot in the dial the needle should drop out on the analog meter. That is how I have tested those switches in the past. Also a loose connection there would not be good. Check the connections at speed sensor on engine also. Hope this may help .
Simon