Why will the excavator not start?

Check battery charge, terminals and ground connections, power cables, the main isolator, fuses and relays, the start switch/button, start interlocks and the starter. On modern equipment the controller may inhibit starting because a safety condition is not met or start permission is missing.

Check the battery, voltage drop along the power cables, grounding, the starter and how freely the engine turns. Also consider hydraulics: a pump that does not unload, faulty pump control, a sticking valve/spool, a permanently loaded function or a mechanically binding pump can load the engine during cranking. If the battery and starter are sound, check for this continuous hydraulic load.

Establish whether fuel is being injected. Check supply from the tank, air in the fuel system, low-pressure supply, starting fuel pressure, the RPM seen by the ECM, crank/cam synchronization, injection permission, active interlocks and faults. On Common Rail, observe rail pressure during cranking. There is no universal starting pressure for every engine; use the specification for the particular system.

At least some fuel is reaching the cylinders. This does not prove that injection pressure, quantity, atomization or timing is correct. Check cranking speed, synchronization, injectors, compression, air supply and the engine's mechanical condition. White or greyish cranking smoke usually means fuel is entering but not igniting properly.

Only where the specific engine manual permits it, a very small amount may be used to compare the engine's response. If the engine fires or runs briefly, investigate the normal fuel supply and injection further. If it barely responds despite normal cranking speed, check air supply, exhaust flow, compression, valves, valve timing and engine mechanics.

Prolonged spraying or a large ether dose can cause abrupt ignition and engine damage. Glow plugs or electric intake heating make use without checking the manufacturer's requirements dangerous. The purpose is to compare behavior, not to start the machine at any cost.

Observe the failed hot start itself: cranking RPM, fuel pressure, actual/desired Common Rail pressure, pump performance, injector return leakage, crank/cam sensors, injection permission and engine/fuel temperatures. Hot fuel can make internal pump or injector leakage more pronounced. Some sensors and electrical components also fail only after heating up.

• Is there fuel, and how does the starter turn?
• Is cranking similar when cold and hot?
• Is there smoke, and what color is it?
• Are there fault codes, visible leaks or damaged wiring?
• Did the problem appear suddenly or gradually worsen?

If a service menu is available, observe RPM, start/injection permission, synchronization and available fuel-pressure values while cranking.