Bad vac. pump or just a leak?

[Sycostang67]

My sister and her husband have picked up a 91 F-250 with a 7.3 and ATS turbo. I asked her how they were liking it and she mentioned that in order for the brakes to work properly, they have to rev the motor up. I haven't been able to get an in-depth look at this truck yet so I dont have a real good clue about anything on it. I will be doing the return lines for them soon, hopefully before they kill the starter and batteries. Would low vacumn be a sign of the pumps imminent demise or more likely it's just a leak somewhere. I figured a vacumn pump would just die, not slowly wither away. I know the pump on my old 6.9 went from working perfectly to doing nothing in a matter of seconds.

 

[berniesouthunt]

Mine died very slow. New vac pump and brakes work a heck of a lot beter.

 

[8seconds]

First and cheapest thing to do is check the belt tension, second put a vacuum guage in line and determine if it is the pump. Pump should be pulling between 28 to 30 lbs.

 

[Knuckledragger]

First and cheapest thing to do is check the belt tension, second put a vacuum guage in line and determine if it is the pump. Pump should be pulling between 28 to 30 lbs.

What he said, except it should pull 28-30 inches. If you could pull 30 pounds, you would have a VERY special pump.

 

[8seconds]

Thanks for the correction Knuckledraggaer, as said 28-30 inches

 

[Sycostang67]

I will get it checked out then, thanks fellas.