87 Buick grand national electronic brakes

[gordyturbo]

What would make the electric brake booster pump run excessively when key is on or when driving?
Note replaced all components except master cyclinder.

 

[TurboDave]

What would make the electric brake booster pump run excessively when key is on or when driving?
Note replaced all components except master cyclinder.

Replaced what components???

 

[1quick6]

That's usually indicative of the accumulator leaking pressure, thus requiring the pump to run more often to keep it charged. Were you throwing new parts at it in hopes of fixing it or did this pop up post parts replacement? Was the accumulator a new one? Is the brake warning light ever lit?

 

[salvageV6]

Accumulator, brake switch, or internal leak.