Brake pressure problem

Nitronut

Registered User
90 SC my brake and abs lights came on, then hard pedal. I check the pump motor relay and pump motor. Pump motor is running but after 5 minutes still running and hard pedal. Replaced accumulator and still the same problem. Removed complete master assembly and found little flow of brake fluid from low pressure line. Cleaned reservoir and flow is better. Removed accumulator and with pump motor running no fluid coming from accumulator port. I assume a bad pump. Any ideas and can I get a pump?
 
Pressure switch not giving a proper reading. The stiff pedal should only be there when low pressure so this is weird if pump is running.
 
90 SC my brake and abs lights came on, then hard pedal. I check the pump motor relay and pump motor. Pump motor is running but after 5 minutes still running and hard pedal. Replaced accumulator and still the same problem. Removed complete master assembly and found little flow of brake fluid from low pressure line. Cleaned reservoir and flow is better. Removed accumulator and with pump motor running no fluid coming from accumulator port. I assume a bad pump. Any ideas and can I get a pump?

This is a bad sign. I would guess that the pump is shot or possibly the inlet is plugged? You made sure the suction hose is clear?

If you did all that, then maybe the pump is bad. New pump is not available for this application, but you can probably get a rebuilt / inspected one from Prior Remanufacturing or SIA Remanufacturing. A used one from this board may also work well. Or, you can buy a new Buick Reatta pump & motor, but they will require some adaptation to work.
 
If I had my brake conversion done I'd sell you my pump for $200.

I have the vacuum booster from an LX and the master cylinder and reservoir from a crown vic to install.
 
Brake Problem

I thought it was strange the pump is running and no pressure. When I cleaned the reservoir I found bits of black debris coming out, no thick gunk. I removed the rubber low pressure line between the reservoir and the pump and it is clear, I removed the motor from the pump and the port into that chamber is clear too. I am going to try and take the pump apart next unless anyone has a way to test the pump? I assume I am correct that the pump takes fluid from the reservoir through the rubber hose and fills the accumulator? Anyone know?
 
There is a small check valve that can get debris in it.....

Give me your e-mail address and I'll send you the schematic of the pump....

For some reason, SCCOA will not let me post it....:confused:

89 - 90 Saab 900 and 9000's have the exact same pump and they are very easy to remove.....
 
I assume I am correct that the pump takes fluid from the reservoir through the rubber hose and fills the accumulator? Anyone know?

Yup, that's how it works. You might say you already tested it by running the motor with the reservoir installed but the accumulator removed. If it's not squirting out brake fluid, it's not pumping.

Here's a crazy question for you. When you replaced the motor, did you make sure to transfer the little drive plate that fits between the motor and the pump? About the size of a quarter, but thicker, and with some slots cut out of it?
 
Yup, that's how it works. You might say you already tested it by running the motor with the reservoir installed but the accumulator removed. If it's not squirting out brake fluid, it's not pumping.

Here's a crazy question for you. When you replaced the motor, did you make sure to transfer the little drive plate that fits between the motor and the pump? About the size of a quarter, but thicker, and with some slots cut out of it?

Center hole is slotted and it has two ears that stick out on either side.
 
When I put the pump motor back I did see the quarter size metal washer with the slot and two tabs, I made sure the pump turned as well as the motor shaft. KMT thanks for the web site, it does show fluid coming from the reservoir to the pump head, then to the accumulator. the-big-e, I would like to see the schematic to see if that's my problem. email: socalrvrepair@yahoo.com. Thanks everyone for the help, I maybe needing a pump head if anyone has one, or know where I can get one.
 
PDF of pump schematic sent.....

If you check the yards for 89 - 90 Saab 900s and 9000s, they have the exact same pump....
 
Last edited:
if the abs light is on you should be able to pull a dtc for the abs system from the data port in the trunk should point you in the right direction
 
First there was a run on the motors, then there was a run on the pumps.....

On the Saabs, the ABS pump / motor assembly is up on the firewall near the DS wiper.....

You have to move the plastic intake tube and a big branch of the engine wiring harness....

I can get the motor out in about 15 minutes....
 
Back
Top