I’m in need of help.
I have a 2000 Ford F-150 XLT with 4 wheel disc brakes. I replaced all of the lines and hoses because the lines to the rear were rotted and the last owner capped it. Replaced all of the calipers, rotors, pads, replaced the master Cylinder, and Master Cylinder Brake Fluid Pressure Sensor. I’ve bled the ABS module, the lines, and bench bled the Master Cylinder in the truck with the Dorman 13911 bleeder kit. It will show some bubbles once the reservoir gets halfway down when manually bleeding the lines. It’ll start to brake at the halfway point in pedal travel, then continue to near bottom and it’ll continue to start to brake. If I pump the brakes it’ll hold the pressure and I can brake like normal. I’m getting really tired and frustrated with a soft brake pedal. When I initially bleed the lines, it’s solid fluid. I’m thinking there could just be more air in the system, but I’ve bled the lines SO MANY TIMES. What could be the cause, what should I do? I really don’t want to take it to the garage and have them quote me $1K to find and solve the issue.

 

Sounds like you have indeed replaced the entire brake system at this point. I am thinking bleed the brakes with a vacuum brake bleeder.
I had a shop do mine and the pedal did seem to firm up a bit. I am betting you have some air in your system.

 

LOL, yeah.😂 Everything but the Brake Booster, ABS Module, and brake pedal itself. I’m thinking the same and I just can’t get the rest out.

 

My wife had an issue recently on her edge. The dealer said the booster was bad, covered under warranty and the ABS was stuck open, I believe. Replaced both and all well.

 

Bleeding when using a vacuum bleeder, one needs to coat the open bleeder threads at the caliper, some use Vaseline, thread sealant, anti-seize, etc to keep air from entering the system through the bleeder threads. Manual bleeding, put a block of wood under the brake pedal to keep the pedal from going to the floor and possibly overextend the mc, causing damage.

Have you checked the abs pump for any valve leakage? That can be done by removing the small rubber caps over the service ports. Place a small object into one port, screwdriver, wire, etc and have someone press the brake pedal, engine needs not to be running, if the "tool" moves outward valves leaking, if it doesn't move, try the other side.

 

I haven't done but I've seen it mentioned several times on this forum. It's also shown in the 2000 Workshop Manual. If the lines to the ABS Hydraulic Control Unit (HCU) have been opened you're supposed to use a scan tool, that works the pistons in the HCU a certain way, As I understand things.

Can't remember exactly who was the expert on it but he mentioned it several times. Search the last couple of years and you'll probably find it.

These words in the search box brought up some good stuff - "hcu forscan bleed"

Apparently it's called a "service bleed".

 

Yep. Problem was when these trucks were built the scan tools that did ABS were damn expensive. Fortunately not anymore.

If Barebones suggestion isn't the problem I would get another master cylinder. That's what a mushy pedal usually is if bled right. Have you checked yours? Have someone press your pedal until it stops. If the fluid swirled it's not working right. Have the pedal held once it stops and make sure the fluid doesn't drop anymore shortly after the pedal stops.

You mention the parts you changed but not with the maker of those parts. There's a lot of junk, hit and miss parts available for these trucks.

EDIT: Just saw you have 4 wheel disk brakes. Doesn't that have a proportioning valve for front and rear? You might want to rebuild that if it does.

 

It does have 4 wheel discs. I have a scan tool and have service bled it through that. And I have not seen a proportional valve outside of the ABS pump. It’s just line. The fitting into the pump for the rear is bigger than the rest, but that’s about it. And the brands I used to were Centric and ACDelco. I’ve now replace the Master Cylinder 3 times, and replaced the ABS HCU and Module from another truck. Seemed to be in good condition, but all same result. Still a mushy brake pedal. Bench Bled the Master, Manually bled and service bled the ABS/HCU, and manually bled the lines. Nothing changed.