'84-89 Dual-Function Reservoir
IF THE IMAGE IS TOO SMALL, click it.
The engine supply line feeds the high-pressure frame-mounted fuel pump, which goes to the in-line fuel filter, which then supplies the fuel rail.
A reservoir marked "DO NOT REMOVE CUP" does not contain a filter. For a replacement O-ring for the cup, buy a NAPA 3268, Fram CG3862, or equivalent filter.
For more info, see this album:
http://www.supermotors.net/vehicles/registry/2742/66025 
