BOSS 1144628 - Caterpillar

Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. To help prevent possible injury, turn the start switch off when changing fuel filters or water separator elements. Clean up fuel spills immediately.
If the engine's fuel system is run dry, fill the fuel tank. Then prime the fuel system in order to remove any air bubbles from the system.
Do not loosen fuel lines at the fuel manifold. The engine components may be damaged and/or loss of priming pressure may occur when the fuel lines are loosened.
Follow these steps in order to prime the fuel system:
Locate the fuel priming pump.
Turn the handle on the priming pump counterclockwise in order to allow the priming pump to operate. This position is the PRIME position.
Operate the priming pump's plunger in order to fill the final fuel filter. Continue until you feel resistance. Note: You may need to pump the priming pump for 25 times or more in order to fill the fuel filter. Furthermore, you may need up to 75 pump strokes to fill the fuel supply passage.
Push the plunger and tighten the plunger in a clockwise direction. Tighten the plunger by hand.
After you pressurize the fuel system, promptly crank the engine. Note: Use the engine starting procedure. Refer to Operation and Maintenance Manual, "Engine Starting" in the Operation Section.