Why Some New Diesel Generators Experience Starting Issues on First Use and Require Air Bleeding?

New diesel generators may experience starting difficulties on their first use, primarily due to the presence of air in the fuel system, which prevents smooth fuel delivery to the combustion chamber. The main reasons include:

1. Residual Air in the Fuel System

During manufacturing, transportation, or installation, air may remain in the fuel lines, fuel filter, or injection pump. If not removed, it can obstruct fuel flow, making it difficult for the engine to start.

2. Fuel Pump Fails to Build Pressure

The fuel pump is responsible for supplying fuel at the correct pressure for proper injection. If air is trapped in the system, the pump may struggle to draw fuel, leading to insufficient fuel pressure and improper injection.

3. Fuel Lines Not Fully Primed

Before the first use, the fuel lines may still be empty. If the fuel has not completely filled the pipelines and the injection pump, the engine may experience fuel starvation, resulting in hard starting or failure to start.

4. Air Leaks During Installation or Transportation

If fuel line connections are not properly sealed during installation or transport, air may enter the system, disrupting fuel delivery. Even if the fuel tank contains enough diesel, the injection system may not function properly due to air blockage.

5. Air Ingress After Fuel Filter Replacement or Maintenance

If the fuel filter is replaced or fuel system maintenance is performed before the first use, air may enter the system. If not properly bled, this can also lead to starting difficulties.

How to Resolve This Issue? (Air Bleeding Methods)

1. Manual Fuel Priming

If the fuel system has a manual priming pump, use it to pump fuel until air-free diesel flows from the return line or bleed valve.

2. Loosening the Bleed Screw

Open the bleed screws on the fuel filter and injection pump, manually prime the fuel until air-free diesel flows out, then securely tighten the screws.

3. Checking Fuel Line Seals

Ensure all fuel line connections are properly tightened to prevent air from re-entering the system.

4. Attempting a Short Crank Start

If manual bleeding is insufficient, a brief engine crank can help use fuel pressure to purge remaining air (but avoid excessive dry cranking).

By following this Genlitec technical recommendation, users can prevent startup failures and ensure reliable generator performance from the first operation.