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.