Which procedure is NOT helpful for diagnosing engine faults?

Diagnosing engine faults typically requires a variety of tests to assess different systems and components of the engine. The procedure that is not particularly helpful in diagnosing engine faults is the fuel level test.

A fuel level test simply measures the amount of fuel present in the tank or the fuel system, which does not directly provide information about engine performance or internal issues. While knowing the fuel level is important for ensuring that the engine has the necessary fuel supply to operate, it does not address underlying mechanical or functional problems that could be affecting engine performance.

In contrast, a compression test evaluates the compression pressures within the engine's cylinders, revealing issues like worn piston rings, damaged valves, or head gasket leaks. A cylinder leakage test complements the compression test by determining where air can escape from the cylinder, thus identifying specific issues more accurately. The power balance test assesses how evenly power is distributed across all cylinders, helping to pinpoint cylinders that may be malfunctioning due to various faults, such as misfires or vacuum leaks. Each of these tests plays a significant role in diagnosing specific engine faults, while the fuel level test lacks that diagnostic capability.