Diagnosis That The Excavator Can Rotate When Starting But Cannot Start (there Is No Smoke in The Exhaust Pipe)

Diagnosis that the excavator can rotate when starting but cannot start (there is no smoke in the exhaust pipe). When starting the engine, if there is no smoke coming out of the exhaust pipe and no popping sound, it is generally a problem with the fuel line. The detailed analysis is as follows:
There is no oil in the fuel tank.
(2) The fuel filter and oil-water separator are clogged.
③ The low-pressure oil circuit does not supply oil.
④ The fuel injection pump fails to pump fuel.
⑤ There is air in the oil circuit.