Altec truck engine revs up and down Why?

[Will I am]

1988 altec bucket truck engine speed goes up and down with pto on but no tools are on will not idle unless u turn pto off any ideas or literature on this ? Truck is a am550h

 

[moondoggie]

1988 altec bucket truck engine speed goes up and down with pto on but no tools are on will not idle unless u turn pto off any ideas or literature on this ? Truck is a am550h

Hydrolic pump engaging? I dont really know.

 

[Will I am]

Pto is on when this is happening

 

[kz1000]

Gas engine?

 

[Will I am]

Diesel

 

[kz1000]

I would look for a solenoid that is used to adjust low rpms to prevent stalling. Most vehicles have some form of anti-stall unit, whether vacuum or other.

 

[Will I am]

This is the same problem I'm having

Hello,
I'm having an issue with my hydraulics on my hi ranger. the hydro pressure cylces up an down constantly which cause the engine to change rpms. It seem like the unloader valve may be worn out. I know the reason of the rpm change is because the pressure rises and moves the throttle clylinder(moving the throttle linkage). It acts like the pump is switching on and off(i know this isnt possible). The acummulator is charge correctly, pump will build good pressure, full on oil, not a filter or strainer problem.
Is anyone familiar with a linesman 2, or a hydraulic problem like this? Any help will be appreciated! thanks

 

[mauldinoutdoor]

Alot of bucket trucks have an idle control for on demand hydraulic pressure. My first truck had a hydraulic hose from the pump to the throttle with a actuator that open the throttle for higher revs to create more flow. My newer truck has an electric setup that is similar. And I have another truck that revs when the pto is on so it has to be disengaged to drive around the yard. Take a look near the throttle on the engine first for any actuators or solenoids that are loose or need attention, that would be my starting point

 

[pro94lt]

I'm guessing it's the 8.2 Detroit?

 

[Will I am]

Mine is hydraulic operated and problem has to do with controls

 

[pro94lt]

What engine does it have? Detroit 8.2 cat 3308?

 

[Will I am]

International or ford

 

[Will I am]

This problem only exists when tools r off and pto is on u can see the hydraulic lines surging with motor speeds

 

[Will I am]

Anyone know about them little spaghetti lines one is white other is orange and where they hook up ?

 

[Will I am]

Anyone have a book on this truck?

 

[johnyrtnow]

This is the

This is the same problem I'm having

did you ever resolve this issue ?my 88 International DT466 is doing same thing !