Why a Diesel Generator Won’t Start: Common Causes and Fixes

Check the fuel supply first

• Is there diesel in the tank? The oil alert also cuts the engine if the oil level is too low.
• Is the fuel valve open? On new units it is often closed for transport.
• Water or dirt in the fuel filter is a very common cause; drain the filter bowl and bleed the system.

Air in the fuel system

• If the set ran out of fuel, air enters the line and the engine will crank without firing.
• Bleed the fuel system according to the manual: open the bleed screw on the filter and the injection pump until bubble-free diesel flows out.

Electrical checks

• Measure the battery voltage with a multimeter. Below 11.5 V, the starter will turn too slowly to fire the engine.
• Check the battery terminals for corrosion and tighten them.
• Listen for the fuel solenoid click when you turn the key; no click usually means an electrical fault or a failed solenoid.

When it is more serious

• If the engine cranks normally but produces no smoke at all, suspect fuel delivery.
• If it produces dense white smoke and will not fire, suspect low compression or incorrect injection timing, which needs a workshop.
• Send us a short video of the starting attempt with sound, and we can usually tell you the cause quickly.