abs accumulator problem

[BILL H]

on my milano verde i noticed that after sitting overnight that it was taking longer and longer to pressurize the the brake system and sometimes the red warning light came on until the system gained pressure. the pump would come on after 3 or 4 pumps of the brake pedal. it has a gm reatta pump that is about 4-5 years old with a milano pressure switch . so i replaced the the accumulator with a GM model. bled the system and although better, it still takes a while to pressurize, runs about 1-2 minutes. if it sits for a few days it takes even longer. the pump comes on after 6 pumps of the brake pedal. i checked for external leaks and found none also replaced the abs fuse just because it had been 8-9 years since i last replaced it. additionally, after the accumulator replacement, my wife reported a hard pedal/ poor braking in suburban traffic on the last 95 degree day. the car is now off the road.
what should i look at next?
thanks in advance

bill
91 164L
88 3.0 milano
73 spider
73 gtv jr

[loach1]

The overnight bleed down of pressure is probably the check valve which is integral with the pump. I don't think it can be removed without destroying the pump though...

An easy check is to pressurize the system and mark the fluid level on the reservoir, then check it again after a few hours. If it is the check valve, the fluid will travel back to the reservoir via the pump's suction line. If in doubt, pinch the suction line overnight and the level will remain the same.

The long pumping is probably the pump going out. Mine takes 15~20 seconds and I thought that was bad. These pumps have a positive displacement design that relies on close clearances that enlarge as they wear, making it harder on the pump to increase pressure.

One recommendation - don't take it apart unless you have a back-up. It is very difficult, maybe impossible to get the rubber seal to shrink back to where it needs to be to prevent leaks.