What Causes the Idle Speed to Increase When Releasing the Clutch on a Cummins Engine?

[MacMelanie]

Here are the solutions for the issue of increased idle speed when releasing the clutch on a Cummins engine: Improper adjustment of the throttle linkage: High idle speed is one of the easiest faults to check and resolve. First, check whether the throttle returns to the minimum position. If it does not, inspect the throttle adjustment and return condition. Adjust the throttle cable limit screw. If the throttle still does not return, check whether the throttle return spring is too weak. Idle spring too stiff or preload adjustment too high: If the fuel injection pump has been recently serviced or adjusted, consider whether the idle speed adjustment is correct and whether the idle spring preload adjustment is too high. If the spring has been replaced, check whether the new spring is too stiff.