CYLINDER COMPRESSION/LEAKAGE TESTS   CYLINDER COMPRESSION PRESSURE The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions. Ensure batteries are completely charged and the engine starter motor is in good operating condition. Otherwise, the indicated compression pressures may not be valid for diagnostic purposes. 1. Disconnect the fuel inlet line to the fuel filter housing. Plug the fuel line from the fuel tank. NOTE: Failure