3100 SERIES INDUSTRIAL ENGINES Fuel System Caterpillar

Fuel System
1.1. Fuel Tank
2.1. Fuel Filters
3.2. Cleaning Primary Filter Element
4.2. Installing New Final Fuel Filter Elements
5.1. Priming The Fuel System

Fuel Tank

Open the fuel tank drain valve to drain water and sediment from the fuel tank. To minimize water contamination, fill the fuel tank in the late afternoon: As the fuel is consumed, air with some humidity must replace the fuel in the tank. By filling the tank in the late afternoon, this humid air is expelled before the moisture can condense on the cool inside walls of the fuel tank.

Fuel Filters

Cleaning Primary Filter Element

1. Stop the engine.
2. Close the diesel fuel supply valve.
3. Loosen the nut on the cover and remove the case and filter.
4. Clean the element and case in clean kerosene or diesel fuel.
5. Before installing the filter, inspect the gaskets. Install new gaskets if necessary.
6. Install the cleaned filter element and case.
7. Prime the fuel system.


Installing New Final Fuel Filter Elements

1. Unscrew and remove the filter. Be sure the old filter gasket does not remain attached to the filter base: Leaking between the new and old filter gaskets will result.


2. Clean the gasket sealing surface of the filter base.
3. Lubricate the new filter gasket with clean diesel fuel.
4. Fill the new filter with clean diesel fuel.
5. Tighten filter by hand until gasket contacts base; then tighten 1/2 turn more.
6. Prime the fuel system.

Priming The Fuel System

If air is trapped in the fuel system, the diesel engine will either not start, or will misfire.

To prime the system:

1. Stop the engine.
2. Loosen the vent cap on the filter base.


Operate the priming pump only when the bleed valve is open. Avoid bleeding excessive fuel.

3. Operate the electric starter, or the hand priming pump if so equipped, until the flow of fuel from the filter is continuous and free of bubbles.



4. Tighten the vent cap.
5. Start the engine. If the engine misfires or smokes, loosen a fuel injection line nut; allow the fuel to flow until free of air bubbles. Tighten the line nut, open the next line nut and continue priming each successive line.