Generator will not start

You've got a short somewhere, energizing the circuit. Why did you replace all of those parts? Were there other issues? You shouldn't throw money and parts at something without knowing what's wrong. I would start tracing the wires back from the starter and find were the short is. Sounds like voltage is getting to the wire after the switches in the circuit.

Sounds like your starter is spinning but not engaging. Low/bad battery, dirty cables. More info in engine would be helpful.

There could be a problem with the starter, or the battery.
But neither one will cause the vehicle to stop running.

it sound like a starter issue if you rock it your effecting starter engagement try tapping on the starter while your trying to start it in nuetral if you hear a change in the starter you know that's the issue. ( the starter)

i believe you are hearing the starter turn over but the bendix in the starter is probably bad which is what makes the starter engage the flexplate (flywheel) so unfortunately whoever told you to replace the starter is right, but lucky for you ford trucks have some of the easiest starters to acess

Hi pitched winding sound yes it is your starter engaged to start then stops cranking and winds with out cranking.

4000 kW is a very big generator. I asume that your is 4000W = 4 kW.
If - with electrical start it should be MicroQuiet 4000.
Never mind by all types of electricaly started engines this will mean:

If by "not engage" you mean that solenoid only clicks, but neither the starter motor is turning, nor the bendix wheel is engaged to wlywheel. This may mean that battery voltage is low, in order to engage the bendix and make its power contact, or the bendix is mechanicaly blocked.
If by "not engage" you mean that solenoid clicks, the starter motor is not turning, but the bendix wheel is engaged to wlywheel. This may mean that the bendix relay power contacts are bad or starter motor collector or brushes are bad.
If by "not engage" you mean that solenoid clicks, the starter motor is turning with a scratching sound, the bendix wheel is partially or not engaged to wlywheel. This may mean that the bendix throw out lever is bent or broken, or the wheels on bendix and flywheel are worn out..

windings in your starter have went bad replace starter or a bad connection
hope this helps

its the silonoid that bolts to the starter.the brushes inside the silonoid are not making good enough contact with the copper probe inside. solution buy a new starter or check the voltage going to the starter by checking the hot from the battery and the hot going from the starter to the alternator.