Vacuum leak help?

[slow_90firebird]

Hey guys been away for a while but hope someone can give me some advice...

Symptoms:
Brake pedal gets hard after more than 1 pump
Brake and Abs lights on after 2 pumps
4 or 5 pumps and the lights stay on for 20-30 sec at idle
Lights go out faster if I revv engine

Also, starting the same day, I noticed after I shut off the truck with the hvac set on floor heat, the vac actuator that moves the flap by my feet returns back to the defrost position. If I restart the truck the heat comes out the defroster momentarily before transitioning back towards my feet...

I'm not sure if it always did that. But the little flap door inside the heater never made noise before...

How should I start looking for vac leaks? I can't spray carb clean like a gasser...

Thanks!

[Mark Nixon]

What year?
Sounds like the vacuum pump might be on it's way out.
Get a gauge and see if it has more than 15 inches of vacuum.

Mark.

[slow_90firebird]

1993 auto 4x4. I didn't realize these vac pumps could go bad... I just had it halfway apart for the o-ring and seal kit installation a few months ago.

So 15" is the magic #? Il check tomorrow.

Assuming the pump is still working, could I use the evap smoke machine to pressurize the vacuum lines with smoke? Or are there 1-way valves that would prevent the smoke pressure from getting around?

[slow_90firebird]

Found the leak!


Thanks! I can't believe that's all it was. When I tested the vac pump though it put out 29-30" so I'm guessing that's good...

Only downside was I broke the plastic barb off the vac sensor... Now I gotta find a way to fix that

[Mark Nixon]

It's the simplest, dumbest stuff that'll make you pull your hair out.
Glad it was actually easy to find!

BTW, that's basically EXCELLENT vacuum at ~29".

Mark.

[slow_90firebird]

Ya I know and the worst part was that I looked at everything else first... Finally I pulled the check valve out of the booster and saw that right away!

I was just worried because this morning I had essentially no power brakes at all and tonight were supposed to get a snow storm. Didn't wanna drive to work tomorrow like that and my car hates the snow...