View Full Version : ABS Pump

02-13-2012, 09:31 PM
My ABS pump is giving me fits! Went to change the accumulator and fluid last week I have the same replacement part as the one that was on the pump, pump was working fine. When I changed the accumulator the pump failed to pump the system back up. I have tried every thing thinking that air is trapped, removed accumulator, cracked the line to the master cyl. and nothing. pump motor is working but will not make pressure. I have done this many times and have never had a problem, I even tried a spare pump and that did not work. Has anyone had this happen and what was the outcome?

02-14-2012, 01:11 AM
Yes. Once I pushed the brake pedal a couple of times and it kicked in. If it whines in a fading pitch sound, its pumping fluid. If it keeps on going, and the lights go off, and it continues to run, it could be the pressure switch or the relay. I had a bad switch which did that. Replaced it and all was well again.

02-14-2012, 07:47 AM
It's not moving fluid at all pump just runs. I even took off the motor and put 12v to it to be sure it was not bound up and it spins fine. the complete system was rebuilt back in 06 and has been free of problems it only has 15000 miles on it at the most.

Mike Puckett
02-14-2012, 09:16 AM
There is a little disk shaped metal coupler that goes between the pump and the motor shaft. It may have fallen out when you replaced the motor. As I recall it is about the diameter of a dime or slightly smaller, 2mm thick, has a slot in the middle, and a couple of ears on the edge.

02-14-2012, 07:27 PM
Nope that's not it. It's a bit of a pain to line it up but all you have to do is hold the pump facing up and bring the motor down on top of it. I took an old pump apart and there is not a lot to it. How it works I'm not 100% sure but I have a good theory. There is a sort of valve that is in the accumulator port I was unable to see a way remove and that is where I think the problem is. With the pump apart, that is impeller out there are ports in the shaft that the impeller rides on. when I blew air through them no air would come out the accumulator port, air came out the port that goes to the master cylinder and the pressure switch port. The valve looks stuck down, there looks to be a spring in the center of this valve and my theory is that when I pumped the brake down to get the fluid out of the accumulator it forced the valve down to far and hung it up or it broke the spring inside that valve. This was the first time I have ever pumped the brake down to remove the fluid from the accumulator and I have changed many of them, all the other times I just let them sit for a time and crack the ball lose screw the new one in and away you go! I have looked all over for a brake down sheet of the pump itself with no luck. If there is one out there it remains elusive.

02-14-2012, 08:07 PM
Duffy sent me a PDF of the pump schematic some time ago.....

I can't post it here as it's 2.32 MB.....:(

Any idea of how I can post it here or I can e-mail it to you.....

02-14-2012, 08:57 PM
Yes email that bad boy to me @ supercoupe38@hotmail.com I will pull one apart and post any findings that may be helpful to others, thank you.

02-15-2012, 12:37 AM
E-mail sent....

02-21-2012, 09:15 AM
Pm sent to the big e .