Fuel System Operation and Tests
LIGHT LOAD ADVANCE OPERATION (ROTARY PUMPS)
retard timing and drop engine rpm under the remaining
Light load advance is used on engines with rotary
load. To compensate, the governor begins to close a
injection pumps to maintain injection pump timing and
metering valve in the light load advance circuit. As flow
engine speed as load decreases. Under full and/or
through the metering valve drops, transfer pressure
consistent loads, transfer pressure in the injection
begins to rise again and acts on the advance piston to
pump is stable, acting on the advance piston to
advance pump timing and maintain engine rpm.
maintain pump timing and rated engine speed.
As the load begins to decrease, a corresponding
decrease in transfer pressure occurs which tends to
LIGHT LOAD ADVANCE OPERATIONAL
CHECKOUT (ROTARY PUMPS)
To check operation of the light load advance, perform the
1. Install JT07158 (FKM10429A) TIME TRAC® Kit.
2. Operate engine at full load and rated speed. Note
injection pump timing on TIME TRAC®.
3. Gradually decrease load to the engine. Timing should
continue to retard as the load is removed, but should
start to advance again as the light load advance begins
to operate at about 50 percent load.
4. If timing does not advance, the light load advance is
not operating properly. Have the injection pump
serviced/repaired by an authorized ADS Diesel Repair
TIME TRAC is a registered trademark of Stanadyne Automotive Corp.