Have 247B Cat with the perkins 3024C. The engine only has about 30 hours. Ran like a top for 30 hours but now has a heavy vibration at idle. Smooths right out when you give it throttle. The shop it is at replaced injector tips. when he cracks the injectors he is getting air in the fuel, but no air anywhere prior to injector pump. Anyone have any ideas before the mechanic breaks the bank guessing on the problem.
