Truck Repair: vscum pump psi, manifold vacuum, vacum pump

Question
how mouch pressure should a vacum pump have on a 1983 ford 6.9 disel have. my brakes are hard to push and it shifts hard please help

Answer
Hi Michael,
Vacuum brake boosters usually operate on manifold vacuum for gas vehicles, which is usually aroung 15 Inches.
I am surprised yours uses vacuum. Sure it doesn't use hydraulic pressure from the power steering pump?

www.autozone.com may have the exact test specs.
Van