HELP Vacuum and brake problems

[rodymartin]

Ok now I have a new to me IDI with a problem.

The truck is a 1992 1/2 with serpintine belt 5 speed.

The problem is the ABS light keeps coming on and lately when I first drive the truck the brake pedal feels as if there is no boost until I go about 10 miles.

I have checked the Vacuum. It reads 15 at the pump. But as soon as the brakes are aplied the vacuum goes to 11 or less.

I have blocked off the brake line it does not bring up the vacuum.

I am begining to think the pump is bad.

HELP this is my daily driver

 

[Mulochico]

My ABS light is on most of the time. A mechanic I trust told me it is more than likely the sending unit on the rear end. I do not have the pedal problems though.

 

[redneckaggie]

The vacum pump should pull at least 21 think the manual says 23 but it should do it within a few seconds of fire up i think you are right, the pump is bad.

 

[gatorman21218]

take off the belt and try to spin the pulley. if it spins without much resistance than the pump is definantly bad. A new pump from napa cost me around 100 bucks and i had to buy the pulley puller to gut the pulley off of the pump.