The paper presents a theoretical study of combustion rate of the kerosene type fuel, as a substitute for the military fuel F–34 (F–35), used in the diesel engines 1DH–FTE, GM 6.5L, the OM 366 LA operated in the mountains of Afghanistan, with unchanged regulation settings of the factory fuel supply system. Fuel assessment showed that the fuel caused many problems, associated with fuel combustion process in diesel engine; this leads to deterioration of conditions of fuel ignition and fuel com-bustion with the excessive pressure increase rate for 1° of the engine crankshaft rotation and strong combustion cycle pressure drop. These changes are the result of mountain climate and the physical and chemical proper-ties of the fuel used.