No Brakes When Key On

[Bill_Ritter]

I have a good solid pedal when the key is off and the accumulator is discharged. But as soon as I turn the key on, the pedal goes straight to the floor. There are no leaks in the lines at all. With the key on the compressor will cycle on after every two presses of the brake pedal. Also something that i noticed is that there seems to be a fountain of fluid that shoots up inside the resovoir every time i hit the brake (you can see it though the site glass on the side of the resovoir). PLEASE HELP ME OUT! I want to drive my car again , its my daily driver...

 

[BJM]

How do the brakes feel in normal use? After discharging, is the pump coming on, does the motor slow down as the pressure rises, and finally does it kick off or try to keep running?

 

[Bill_Ritter]

Originally posted by BJM
How do the brakes feel in normal use? After discharging, is the pump coming on, does the motor slow down as the pressure rises, and finally does it kick off or try to keep running?

There are no brakes in normal use. The pedal goes to the floor. When the pedal is on the floor the front brakes drag lightly, but nowhere near being safe to drive. After discharging with the key OFF the pedal is very solid and everything feels good. But as soon as you turn the key ON the pedal will go to the floor and the pump comes on. After the pump shuts off and the system is up to normal pressure you can hit the pedal twice before the pump kicks on again. The pump sounds strong and does not sound like it is straining to build pressure at all.

 

[GN ERGY]

I know there is something at www.gnttype.org for trouble shooting the powermaster. Hope it helps you out.
Tarey D.

 

[BJM]

Try unplugging the PM and after discharging the pressure, go driving, do the brakes work well? I had to the same thing, the pedal is stiff but the car is certainly quite stoppable. If the brakes themselves work then the master cylinder portion of the PM is working. I am trying to fathom how the boost circuit could cause the symptoms you describe. Did this all happen at once or progressively over time?

Could it be bad rear brakes, with no boost the pedal might feel pretty good. If the pedal goes down really easily with boost, does it truly hit the floor? If the rear brakes were leaking then the pedal would go down really low before the fronts did anything. With old squishy front brake hoses on an old car you might no longer have enough travel in the master cylinder with a rear hydraulic leak and you would have the problem you describe.

One way to check would be to lower the fluid level below that notch joining the front and rear reservoirs and with the system charged up (lid on!) pump the brakes about 50 times hard. See if you have lost any of the rear fluid after that, it might be a small leak in the rear (or front) that only makes itself noticeable when you have boost in the system.

 

[turbofish38]

I've seen this problem a few times and its the PM leaking internally. There are some o-rings that detiorate over time. Sounds like you either have to rebuild the PM or replace it.

Eric Fisher

 

[Bill_Ritter]

I did the troubleshooting from GNTTYPE.org and I have good news and bad news. The bad news is that my problem was the PM leaking inside. The good news is that a buddy of my dad's hooked me up with a new unit for FREE! I owe him big time!
Thanks for all of your help guys! I can finally drive my car again