1974-76 Models

With injection pump installed on vehicle, remove protective cap from end of control rod (injection pump end). Remove vacuum connection from top of governor housing.
While holding adjusting lever in full stop position, place finger over vacuum fitting on top of governor housing and release adjusting lever. Observe reaction of control rod.
NOTE: Testing governor assembly may be necessary if engine shows too low and output, heavy smoking, irregular running, faltering or lope during idle, or surpassing full-load RPM on a level stretch of road under no-load conditions.
If diaphragm and housing are properly sealed, control rod will only extend a short distance out of injection pump. If control rod is either fully extended or slowly extends (while still holding finger over vacuum connection), then a vacuum leak exists either in diaphragm or governor housing.
If a leak exist, it will be necessary to disassemble governor housing. Remove 4 screws securing diaphragm housing to injection pump. Remove bolt securing diaphragm to control rod and remove diaphragm. If diaphragm seems stiff or brittle, it must be replaced.