Injection Pump Repairs
Figure 4-81 shows a typical test stand installation. The test stand incorporates a 2 to 15 H.R electric motor,
depending on the particular model used, which drives the injection pump. The stand’s motor simulates the
automotive engine with the rpm controlled on the machine by the operator and not by the throttle opening. Various
tests and adjustments are performed. Some are: Electric solenoid pull-in voltage, housing pressure cold advance
solenoid operation, face cam position, min-max governor, return oil volume, housing pressure, transfer pump
pressure and automatic advance adjustments. Actual calibration of fuel delivery is not adjustable within the head
and rotor assembly but is affected directly by some of the above adjustments. Various rpm ranges and throttle
openings are used to check output of the pump.
It should be understood that the injection pump is designed to deliver a metered amount of fuel at the proper time and is therefore incapable of delivering a rich or lean mixture. It should also be understood that other than a failure of the governor weight retainer ring or the correction of the min-max governor, the injection pump will have very little to do with a rough idle condition and therefore generally should not be sent to the local Roosa Master shop for rough idle.