In Figure 1 the six delivery valve holders (barrels) are pictured on the top portion of the pump body. The holders house the delivery valves and the return spring/plunger assembly. A special socket is required to access the delivery valves. In Figure 2 you should note when removing the holder to be careful not to drop the return spring/plunger. Usually there are shims on the assembly to balance the fuel flow of each plunger. Figure 3 shows the delivery valve assembly being removed. Some pump models, most commonly the 160 hp and 175 hp P7100s, have copper or steel shims under the delivery valve seat located on top of the plunger/barrel assembly shown in Figure 4. A breakdown view of these parts is shown in Figure 5.