Fuel System Checks

Make sure the fuel shutoff valve (if used) is open. If the shutoff valve is even partially closed, it may cause erratic engine operation due to an inadequate supply of fuel to the fuel pump. Fill the tanks with the recommended fuel. Keeping tanks full reduces water condensation and helps keep fuel cool, which is important to engine performance. Full tanks also reduce the chance for microbe (black slime) growth. For fuel recommendations, How to Select Fuel.

Do not use external starting aids. If an external starting aid is used, such as a starting fluid, the heat generated by the external fuel source will cause the injector tips to be damaged when the fuel cools them. The internal injector components can be scored from running without lubrication.

If air has entered the fuel system, the fuel system must be primed to ensure prompt starting and even running. Priming the fuel system includes the use of special tools. Authorized Detroit™ service outlets are properly equipped for this type of service. Never use the starting motor and fuel pump to prime the fuel system. Prolonged use of the starting motor and fuel pump to prime the fuel system can result in damage to the starter, fuel pump, and injectors. Priming of the fuel system is required if the fuel system has been opened.

Drain off any water that has accumulated in the coalescer. Water in fuel can seriously affect engine performance and may cause engine damage, How to Drain the Fuel Coalescer.