I own a 97 f-150 4x4, 4.6 liter with 4wabs.
Problem is a soft brake pedal and extra effort to brake at any speed.
Replaced master cylinder. Power booster check valve,
both front calipers, hose's, pads and installed sloted front rotors and replaced rear shoe's and hardware.
Problem started after last summer from a vacation trip. Bleed brakes 6 times and used 2 quarts of brake fluid. Also checked push rod at booster, okay.
Brake pedal has 2" travel with engine off, 3" when engine running.
What could be the cause? Brake booster or
Any help would be great!
It sound slike you may have air trapped in the upper part of the Anti lock hydraulic module. Try bleeding it but start from the top lines.
DON'T pump and hold on a Ford system. Have someone inside the truck hold the pedal, you loosen the bleeder. Keep the pedal down until you tighten the bleeder then release the pedal. Repeat until there are no bubbles or foam like brake fluid.