F 250 4WD Pickup V8-6.9L DSL (1983)
Fig. 3 Vacuum pump installation. V8-420 (6.9L) engine. 1983---84 shown, 1985---87 similar
On vehicles with diesel engines, insufficient vacuum is available to operate the vacuum booster brake. Vacuum is supplied from a vacuum pump located
on the top right side or left front side of the engine, Figs. 1, 2, & 3. This pump is driven by a single belt off the alternator. These vehicles also
incorporate a low-vacuum switch that actuates the brake warning light when vacuum is below a specified level. This switch senses vacuum through a
fitting in the intake manifold that intercepts vacuum flow from the pump.
