The issues of maintaining the reliability of the functioning of power units of mobile technical equipment designed to deliver specialized equipment and personnel to firefighting sites are being investigated. In relation to moderately boosted power units (4Ch11/12.5; 4ChN11/12.5) for the chassis of medium-duty fire-fighting vehicles (ZIL-5301; GAZ-3403), statistical patterns of changes in the characteristics of their technical condition depending on the operating time in engine hours were studied experimentally. The patterns make it possible, with a high degree of reliability, to substantiate the relationship between the technical condition
of power units and their fuel equipment with indicators of the effectiveness of the use of mobile fire fighting equipment: power, fuel efficiency and environmental safety in the processes of their long-term operational operation for their main purpose – fire extinguishing.