Bosch Inline Injection Pumps
When the individual pumps are contained in a single housing with their high-pressure fuel outlets arranged in a straight line, the assembly is referred to as a PLN (pump-line-nozzle) system. Bosch and other pump OEMs call these pumps PE models (the P for “pump” and the E for “enclosed camshaft”), since they are mounted lengthwise within the base of the pump housing and driven from the engine gear train. As shown in Figure 19-5, these pumps can be mounted in one of three ways: base, cradle, or flange. The type of mounting is determined by looking at the drive end of the pump. When an inline pump is flange mounted, a third letter, S, is added to the designation, with the pump designated as a PES unit.
Inline pumps are referred to by their physical size, which relates to pumping plunger diameter, how much fuel they can deliver (quantity), and the pressure they can deliver to the nozzle. These pump sizes are M, A, MW, and P. Therefore, PES-A, PES-M, PES-MW, and PES-P indicate pumps with an enclosed camshaft of the size represented by the letter. Pump size examples are included in Figure 19-6.