my 1993 f-150 is giving me a fit. i got into it yesterday andn the brake pedal went to the floor. there is some loss of fluid, but some remains in the resivoir. i see no fluid loss around the master cylinder.

any ideas appreciated.

 

You have a broken line somewhere in the system.

Look underneath the truck for a puddle of fluid.

Find where the leak is coming from and replace the offending line.

Bleed the brakes and you're back in business!

 

Could also be one of your wheel cylinders. Check the rear brakes from the back, looking for fluid.

 

Fluid had to go somewhere, find the leak.