In the brake master cylinder reservoir on the drivers side of the engine compartment near the firewall
Under the hood on the driver side.
Not knowing what year the truck is, my guess would be coolant. Check or monitor the level of all the fluids including brake fluid.
( 3 ) according to the owners manual
In a 2001 Ford F-250 : ( DOT 3 brake fluid meeting Ford specification ESA-M6C25-A is used in the brake system )
front passanger side of engine. It runs off the camshaft
Store under the drain pan of the transmission.
Sounds like a master cylinder.
Remove the tire and wheel. Remove the brake pad Springs. The brake pads and break assembly will come off. Reverse the process to install the new brake pads.
Run the truck backwards to about 10 Mph, hit you brakes very hard. This will adjust your brakes in general.
The Ford F250 is a 3/4 ton truck and the F150 is a 1/2 ton truck. The main purpose for these differences, is pointing out the towing capabilities for each truck. The major difference between the F150 and F250 is size and power. The F250 has a more powerful drivetrain and can tow and haul more cargo.
brake pressure loss and pedal going straight to floor is mostly caused by loss of brake fluid or air in brake system look under car and on inside of wheels to see if fluid is leaking. check brake fluid level at master cylander if no fluid seems to be leaking, have the brake system bled for air. this is the simplest remedy to start with if that doesnt fix it have the brake power booster checked to make sure fluis is not leaking into that also check on firewall in engine bay round booster for fluid and on inside of cab on firewall for fluid
you take the wheel off and take the drum off and then you get a haynes book and figure it out. ain't tht hard there pale