I have a natural gas driven generator, synced with other generators. Can a generator become a motor and turn the driver ?

I have a natural gas driven generator, synced with other generators. Can a generator become a motor and turn the driver ?
That depends entirely to the type and circuitry of the generator.
A simple DC motor with magnet and rotating coil will function both as motor and as generator.
A (by electronic circuit) stabilized generator will only function as generator, unless modified.
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Are you perhaps trying to create a Perpetuum Mobile??
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;)

How generator becomes motorization