SPOOL AS-DIFFERENTIAL 6P4711 - Caterpillar

Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
Engines with Electric Priming Pumps
There are many different types of electric priming pumps. These fuel pumps can be put into two categories. Remotely mounted fuel priming pump and secondary fuel filter mounted priming pump.
Illustration 1 g03721131
(1) Typical example of a remotely mounted priming pump.
(2) Typical example of a priming pump mounted on a secondary fuel filter. Priming the Fuel Injection Pump for a Variable Speed Engine
Turn the keyswitch to the ON position and allow 180 seconds for the electric priming pump to prime the system.
Turn the keyswitch to the OFF position and then start the engine with the throttle in the closed position. Operate the engine at idle with no load for 60 seconds and then shutdown the engine.
Wait 30 seconds and start the engine. This procedure will remove any air that could be trapped within the fuel injection pump. Check for leaks in the fuel system. Refer to this Operation and Maintenance Manual, "Starting the Engine" for more information.Priming the Fuel Injection Pump for a Constant Speed Engine
Turn the keyswitch to the ON position and allow 180 seconds for the electric priming pump to prime the system.
Turn the keyswitch to the OFF position and then start the engine. Operate the engine with no load for 60 seconds and then shutdown the engine.
Wait 30 seconds and start the engine. This procedure will remove any air that could be trapped within the fuel injection pump. Check for leaks in the fuel system. Refer to this Operation and Maintenance Manual, "Starting the Engine" for more information.Engines with Mechanically Operated Priming Pumps
Illustration 2 g03721133
Typical example.
Loosen the vent screw on the secondary fuel filter. Note: The fuel priming pump is mechanically operated by the camshaft. In curtain positions the camshaft lobe can act upon the arm of the fuel priming pump reducing the hand priming pump ability to prime. This condition will be felt as low resistance on the operating arm. Rotating the crankshaft will move the camshaft lobe acting on the priming pump arm. Rotating the camshaft will allow the priming pump full ability to prime.
Operate the lever (1) on the priming pump. When fuel free from air can be seen, close the vent screw. Tighten vent screw securely.
The fuel injection pump will self vent. Turn the keyswitch to the ON position and operate the lever on the priming pump. Operate the pump by hand for 2 minutes and then stop.
Turn the keyswitch to the OFF position and then start the engine. Operate the engine with no load for 60 seconds and then shutdown the engine.
Wait 30 seconds and start the engine. This procedure will remove any air that could be trapped within the fuel injection pump. Check for leaks in the fuel system. Refer to this Operation and Maintenance Manual, "Starting the Engine" for more information.