769D Off-Highway Truck and 771D Quarry Truck Caterpillar

Illustration 1	g00797128

The hand priming pump is located on the right side of the engine. The engine can be accessed under the engine cover on the platform.

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Illustration 2	g00797129

1. Turn the priming pump plunger counterclockwise and pull out the priming pump plunger. This will unlock the hand priming pump.

2. Use the hand priming pump in order to fill the engine fuel lines with fuel. Continue to prime the fuel system until the pump resists operation.

3. Start the engine and inspect the fuel system for leaks.

   Note: If the machine is equipped with the Caterpillar Prelubrication System, the engine will activate a cycle of the prelubrication system before the engine starts. A "P" will appear on the operator's display until the prelubrication is finished. If the machine also has the ether starting aid, an "E" will appear on the operator's display until the engine starts.

4. If the engine does not start after two or three attempts to crank the engine, repeat Step 2 and Step 3.

5. If the engine runs rough after start-up, shut off the engine. Purge the air from the fuel system.

   1. Loosen the vent plug on the block for the fuel return. The block for the fuel return is located at the upper left rear of the engine.

   2. Prime the fuel system until a continuous stream of fuel is flowing from the opening. Catch the fuel in a suitable container.

   3. Install the vent plug.

   4. Start the engine. Run the engine at LOW IDLE until the engine does not run rough.

6. Push the priming pump plunger inward and turn the priming pump plunger clockwise. This will lock the priming pump plunger.