99617 Mercury PIN

Any mechanic attempting make adjustments to the set point rpm should be trained in governor adjustment.
Engine rpm must be checked with an accurate tachometer. Refer to Testing and Adjusting, "Engine Speed - Check".Low Idle Adjustment
Note: Refer to Technical Marketing Information (TMI) for the correct low idle setting.Start the engine and run until the temperature of normal operation is reached. Check low idle rpm with no load on the engine. If an adjustment is necessary, use the procedure that follows:
Remove the sealed cover over the high idle adjustment screw and the low idle adjustment screw.
Illustration 1 g01029132
Idle adjustment (typical example) (1) High idle adjustment screw (2) Low idle adjustment screw (3) Tachometer drive
To adjust the low idle rpm, move the governor control to the low idle position and turn adjustment screw (2). Increase the engine speed and then return the control back to the low idle position in order to recheck the setting.
When governor adjustment is correct, install the cover over the adjustment screws.When the cover is installed on the governor, the idle adjustment screws fit into holes in the cover. The shape of the holes will not allow the idle adjustment screws to turn after the idle adjustment is done and the cover is installed.
Install a new wire and seal to the cover bolt.Checking the Set Point of the Engine (Balance Point)
The set point of the engine must be adjusted to specifications in order for correct operation of the engine. High idle rpm is not an adjusted specification. The set point of the engine (balance point) is full load rpm plus an additional 20 rpm. The set point is the rpm at which the fuel setting adjustment screw and the stop (or the first torque spring) begin to make contact. At this rpm, movement can be felt between the fuel setting adjustment screw and the stop (first torque spring). When additional load is placed on the engine, the fuel setting adjustment screw and the stop (first torque spring) will become stable against each other. The set point of the engine is controlled by the fuel setting and the high idle adjustment screw.
Table 1
Required Tools    
Part
Number    Part Description    Qty    
8T-0500     Continuity Test Light     1    
9U-7400     Multitach Tool Gp     1    
Illustration 2 g00300249
9U-7400 Multitach The 9U-7400 Multitach Tool Gp is used to check the set point. Refer to Tool Operating Manual, NEHS0605 for instructions on using this tool group. Note: Do not use the tachometer unless the tool's accuracy is known to be within 1 rpm.If the set point is correct and the high idle speed is within specifications, the fuel system operation of the engine is correct. The set point of the engine can be summarized by the following characteristics:
The setpoint is found at full load speed plus an additional 20 rpm.
Contact is made between the fuel setting adjustment screw and the stop (first torque spring).Use the procedure that follows to check the set point. Refer to Special Instruction, SEHS7050, "Techniques For Loading Engines".
Connect a tachometer which has good accuracy to the tachometer drive.
Illustration 3 g00343139
Installation of the circuit tester (1) Brass terminal screw (2) 8T-0500 Continuity Test Light
Connect the clip end of the tester (2) to the brass terminal screw (1) on the governor housing. Connect the other end of the tester to a place on the fuel system which is a good ground connection.
Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Start the engine.
With the engine at normal conditions for operation, run the engine at high idle.
Record the speed of the engine at high idle.
Slowly add a load to the engine. The continuity test light should just begin to illuminate with a minimum output of the light. This is the set point.
Record the speed (rpm) at the set point.
Repeat Step 6 several times in order to ensure that the reading is correct.
Stop the engine. Make a comparison of the information from Steps 5 and 7 with the full load speed from the engine information plate. If the engine information plate is not available, refer to Technical Marketing Information (TMI) for the full load speed. The tolerance for the set point is 10 rpm. The tolerance for the high idle rpm is 50 rpm in chassis, and 30 rpm on an engine that is bare. If the readings from Steps 5 and 7 are within the tolerance, no adjustment is needed.Note: The engine high idle speed is stamped on the engine information plate. For some applications, there is a possibility that the high idle rpm will be less than the actual lower limit. This can be caused by high parasitic loads such as hydraulic pumps, compressors, etc. Adjusting the Set Point (Balance Point)
If the set point and the high idle rpm are within tolerance, no adjustment is necessary.
If the set point for the engine rpm is not correct, remove the sealed cover that is over the high idle and low idle adjustment screw.
Illustration 4 g01029132
Idle adjustment (typical example) (1) High idle adjustment screw (2) Low idle adjustment screw (3) Tachometer drive
Turn adjustment screw (1) in order to adjust the set point to the midpoint of the tolerance.
When the set point is correct, check the high idle rpm.