TM 9-2320-361-34 2-6. GENERAL TROUBLESHOOTING INSTRUCTIONS (Contd) c. Double check before disassembly. The source of most engine problems can be traced to more than one part in a system. For example: (1) Excessive fuel consumption may not be caused by the fuel pump alone. In addition, the trouble could be a clogged air cleaner reducing air inflow or a restricted exhaust passage causing abnormally high back pressure. (2) Engines often are disassembled in search of a complaint and the real evidence of the problem is destroyed. Check again to be sure an easier solution to the problem has not been overlooked. (3) Check all tags, service request forms, and vehicle logbook for repair history. This may help lead to source of problems. d. Before attempting to correct a problem, diagnose the cause of the problem. Do not allow the same failure to occur again. e. This troubleshooting covers in-vehicle engine repair. For out-vehicle engine repair, refer to TM 9-2815-210-34-1,-2-1, 2-2, and -34P. 2-2