Please help with powermaster diagnosis....

[Pats-GN]

Hey guys, I tried to use the flow chart on gnttype and I'm still stumped. Brakes work great for 30minutes then I pop the 30amp powerbrake fuse everytime. I did the 10 pumps with the key off, takes 7sec for the brake light to go off, 14 seconds for the motor to stop and it doesnt cycle within two minutes. Dont know if i'm doing this correctly. The PM motor runs with every pump with the key on, i'm also getting a pulsating pedal when driving. The accumulator ball was just replaced about 10,000miles back. Dont see any external leaks around the PM. Any help greatly appreciated.

thanks
pat

 

[zeus87gn]

It's possible it may be the Acc ball again, but it sounds like you are loosing your pump. If you have the money, replace it. Hank Terry sells brand new units for quite the reasonable price. About $150 If memory serves.

 

[Pats-GN]

Whats the best way to determine if its the pump or accumulator? I'm not going to throw parts at this thing again :wink:

 

[zeus87gn]

Pat,

You are right on the borderline in the diagnostic procedure. I'm sending you an email attachment that will help explain why I think it's the motor. Basically, if you don't have the special tool, you have to judge based on time, and you are right on the border time. So it may be both the motor and the accumulator causing problems.

Read it and we'll type more.

Patrick

 

[GNRick]

I have the powermaster troubleshooter book around here somewhere. When I was having powermaster problems, I too followed the flow chart. Problem pointed to the accum. ball. I called Hank Terry and he agreed. So I replaced the ball and still had the problem. Called Hank back, bought/replaced the motor, and that solved the problem. Another option is to trade your PM with Kirban as he gives credit for it and he can sell you a "new" one. Also check Autozone website as they used to carry them with lifetime warranty.

 

[Pats-GN]

Thanks for the help. I'm thinking about just going with the Autozone PM. Its $350 and it has a lifetime warranty. Seems like a better option than throwing parts at it. What else should I replace while i'm at it? Brake lines and wheel cylinders?

Thanks
pat

 

[grkgn]

hi

if your poping a fuse this is your problem change the pump motor and awitch at the same time if you just change the pump you will short it out after two days

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

Those Pumps Had Phenolic Vanes In Them, Pumping Brake Fluid To High Pressure In The Accum. Those Vanes Wear Out Quickly. When Worn, The Pump Can't Reach The Switch Pressure Cut Off To Shut Off. The Other Problem With The 12v Pumps Is When The Seal Wears Out Between The Pump And The Windings. When The Elec Part Is Flooded With Brake Fluid, It Shorts Out, Popping The Fuse.

 

[SVORay]

Those Pumps Had Phenolic Vanes In Them, Pumping Brake Fluid To High Pressure In The Accum. Those Vanes Wear Out Quickly. When Worn, The Pump Can't Reach The Switch Pressure Cut Off To Shut Off. The Other Problem With The 12v Pumps Is When The Seal Wears Out Between The Pump And The Windings. When The Elec Part Is Flooded With Brake Fluid, It Shorts Out, Popping The Fuse.

It's only a fuse

 

[J-B Racing]

How do I find Hank Terry???
I am looking for an Accumulator Ball.....

 

[GNRick]

How do I find Hank Terry???
I am looking for an Accumulator Ball.....

Here is his website. But he only sells the pump. There is a complete powermaster on ebay for $699. For the ball, you would have to contact Kirban, or post in the parts wanted thread.

GM PowerMaster Sales

Good luck.