Power brakes not working

Do you feel the brake pedal go down when you hold you foot on the pedal while starting the truck ? Maybe the power booster is bad. The power brake booster is vacuum controlled in most cases an if you hold your foot on the brake pedal when starting you should feel the pedal go down if working correctly .

neither is bad. The proportioning valve is kicked and they can sometimes be a bear to re center. Here's the best way I've had success doing that. Before you try opening up any more bleeder screws you, 1)top off the brake fluid reservoir, 2) slowly pump the brake pedal, not all the way to the floor and without the engine running but with the key on, about 20 to 30 times. After you do that you very quickly hit the brake pedal very hard but not all the way to the floor. The repeated slow pumping of the pedal will very slowly put pressure into the line, even if it's air it will compress a little at a time and when you jab the pedal that one time at the end it will re-center the valve. Now here's the key. If the brake light is on it should shut off when that valve centers itself. That's when you must bleed the air out but whoever you have helping you tell them not to push the pedal all the way to the floor again or the valve will pop again. Open the bleeder to the caliper that had the blown line and then have them push slowly down on the pedal only half way to the floor and then stop pushing and hold position til you tighten the bleed screw. After you close the bleeder screw they can let up and do it again. If he pushes it to the floor and you hear a click that means the valve kicked again and you need to start over. Time consuming, yes but it works. I hope this makes sense. Sometimes it's hard to relay what I do to words on paper,.
Dale

bad booster, or vaccumme leak

The most obvious cause for a hard pedal is simply not enough vacuum. Check the brake power booster by pumping on the brake pedal while the car isn't running. Continue pumping until you've "bled off" the vacuum from the booster. Hold the pedal down while you start the car. The pedal should go down a bit more beneath your foot. If it doesn't, then you should examine the connection between the vacuum hose of the brake power and the engine's vacuum.
Replace the brake power booster if the connection's fine, which would fix the hard brake pedal problem.

It may be your calipers need replaced. Check them for signs of wear. Look at the metal spring where the brake pads sit.
Apply tension to the pad and see whether you hear a pop. If you do, the brake pad is moving too much on the bracket. Replace the caliper. This could help the hard brake pedal.

In most cases if the power brake booster is bad, The brake pedal is very hard to push down. You may know it is starting to go bad if you hear a hissing/sucking noise when pushing the brake pedal. Hope this helps

NO. the vacuum is used to make the brake pedal easy to push, power brakes. the pedal would be hard without vacuum, that is why the pedal gets hard with the key off and engine not running. the problem you are having is more of a hydraulic problem.
Have the brakes checked asap. the brake system may have a leak causing the pedal to go low. check the fluid level and if it is low or empty then there is a problem, could be a rotted brake line leaking or a wheel cylinder leaking.

Dead Battery

need to replace the power brake booster. the vacuum diaphragm in the booster has bursted causing the noiseand the hard brake pedal.

When you press on the brake? Have your brake vacuum assist checked. It,s that bigspaceship looking thing between the brake master cylinder an firewall. good luck and be safe.

First you need to check the brakes lines and the brake pads must be replaced on your car they may be worn out........ Get it checked from the local service center........