TUBE AS 5V3719 - Caterpillar

Do not allow dirt to enter the fuel system. Thoroughly clean the area around a fuel system component that will be disconnected. Fit a suitable cover over disconnected fuel system component.
Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire.
Use a suitable container to catch any fuel that might spill. Clean up any spilled fuel immediately.
Priming Pump Operation
Note: 235-8725 Fuel Transfer Pump and Filter Gp and the 235-8724 Fuel Transfer Pump Base As are for the continuous flow version of this pump. The applications that use this pump will not have a mechanical transfer pump. These pumps will always be energized when the engine is running.
Illustration 1 g01425349
Cut out view of the priming pumpWhen the pump is energized the following describes the fuel flow:
Fuel is drawn from the fuel tank into inlet port (4) .
The fuel then flows to the fuel filter and to the water separator, if equipped.
The fuel is pressurized after entering the inlet chamber of the pump.
The fuel travels out of the number one valve (2), through outlet (3), to the mechanical transfer pump, if equipped.When the pump is not energized and the engine is running the following describes the fuel flow:
The fuel is pulled by the mechanical transfer pump through inlet port (4) to the fuel filter and the water separator, if equipped.
The fuel then enters the inlet chamber of the pump that exits at the number two valve (1) into the outlet (3) .
The mechanical transfer pump creates the negative pressure that opens the number two valve.The Electric Priming Pump Does Not Run (No Sound)
Intermittent electrical problems are sometimes resolved by disconnecting and reconnecting connectors. If the status is changed due to disconnecting and reconnecting a connector, there are several possible reasons. The likely reasons are loose terminals, improperly crimped terminals, moisture, corrosion, and inadequate mating of a connection.
Unplug the two pin Deutch connector from the priming pump. Visually inspect each terminal in the connector. Verify that the terminals are not damaged. Verify that the terminals are properly aligned in the connector and verify that the terminals are properly located in the connector.
Carefully inspect each wire for signs of abrasion, of nicks, and of cuts.
Exposed insulation
Rubbing of a wire against the engine
Rubbing of a wire against a sharp point
Perform the 45 N (10 lb) pull test on each wire. Each terminal and each connector should easily withstand 45 N (10 lb) of tension and each wire should remain in the connector body. This test checks whether the wire was properly crimped in the terminal and whether the terminal was properly inserted into the connector.
Use a voltmeter in order to check the voltage at the connector while the priming pump switch is turned to the ON position. Wiggle the wiring during the measurement in order to detect an intermittent problem with the wiring.The voltage is adequate when the voltmeter reads voltage between 20 and 28 V. The voltage is low when the voltmeter has less than 20 V.
Reconnect