Brake problem

[merv dessent]

We have 1996 F350 powerstroke and when we operate brakes the second push of the pedal will result in the pedal going hard.The vacuum pump is working but it is possible that it cannot keep up.We replaced the booster yesterday and the problem is still there.Any suggestions?

[mschn99]

Originally Posted by merv dessent

We have 1996 F350 powerstroke and when we operate brakes the second push of the pedal will result in the pedal going hard.The vacuum pump is working but it is possible that it cannot keep up.We replaced the booster yesterday and the problem is still there.Any suggestions?

i have seen weak vacume pumps cause a concern like this.......what you want to do is feel how much vacume the booster is putting out after someone has stood on the brakes for a while......i bet it builds enough vacume for the one braking and takes quite a while to build enough for the second.......Marc