Question

after finding the problem the mechanic cleaned the carburettour ,started the engine and found it working smoothly - correct the sentence

Answer 1

after finding the problem, the mechanic cleaned the carburetor, started the engine and found that it was working smoothly

Answer 2

The correct way of sentence formation is:

After finding the problem, the mechanic cleaned the carburetor, started the engine and found that it was working smoothly.