Use a vaccum gauge to check what vaccum you have before rebuilding or changing pump. Read the vaccum available at pump source only and if it is at specification check out your vaccum lines and fittings for leaks with a minivac type tester if vaccum is far less when system is hooked back to the pump. Threads posted in archives search should give you a lot of guidance. Good maintenance check anyways on these older cars. Also by coincidence you may have only one half your braking system working yet pedal not reaching floor. Just jack up one wheel and have friend hold brake pedal on and try to turn that wheel by hand. Jack up other end of car and repeat. If after holding the pedal down for a minute and the wheel turns that half of your master cylinder is bypassing. Like most posts do not see how the wash could have affected the brakes in the method you describe other than a lot of soap getting on the disks and pads. (and I mean a lot) If that is the case should rain wash or wear off in a few days. So if brakes are gradually improving give them a day or so before looking for a problem.