I really have to press *** the pedal to stop. Is this a booster problem? I had it replaced last year because the pedal was too soft. thanks

You have air trapped in the braking system somewhere. Have you bled the system thoroughly at all four wheels?
Have you changed the front calipers recently. Many years ago, I helped a friend mount new calipers on his vehicle, and we put the new calipers on the wrong side -- right one on the left side and vice versa. In this configuration, the bleeder screw wound up on the lower portion of the caliper instead of at the top, where it needs to be to allow trapped air to come out. Just a thought.

Hi. Would you elaborate on what you saw and touched on the booster? Changing the master does not affect booster operation. Maybe you overlooked something or maybe you have two separate issues. I recommend diagnosing the booster first. Perform three tests. Is the booster receiving 16 in Hg? If not, what is it getting for vacuum? Second test: Start the engine, idle for one minute and check. Is there power assist? If the pedal is hard then the booster is bad. If it passes the third test: Shut the engine off and press the brake pedal down with normal pressure. You should have enough vacuum stored to pump the pedal two times. If not, either the external check valve is bad or the booster is defective. Please run more diagnostics and let me know. Also please write back and explain exactly how the brakes were bleed. Maybe they need to be done again. Good Luck.

Some part of the brake linkage must be pressing on a vacuum hose. Check under dash as well as under hood.

possiable brake booster. if you hear a hissing sound and truck runs rough if not possiable master cylinder.

Usually if the booster fails, the pedal is very hard to push enough to make the vehicle stop.
If the pedal sinks or is soft, the master cylinder is allowing fluid to bypass the pistons inside.

Not sure if you have done all this.



BRAKE BOOSTER INSPECTION

Functional test:
1. With the engine stopped, Depress the brake pedal several times, then depress the pedal hard and hold that pressure for 15 seconds. If the pedal sinks, the master cylinder, brake line or a brake caliper is faulty
2. Start the engine with the pedal depressed. If the pedal sinks slightly, the vacuum booster is working. If the pedal height does not vary, the booster or the check valve is faulty

Leak Test:
1. Depress the brake pedal with the engine running then stop the engine. If the pedal height does not vary while depressed for 30 seconds, the vacuum booster is OK. If the pedal rises, the booster is faulty
2. With the engine stopped, depress the brake pedal several times using normal pressure. When the pedal is first depressed, it should be low. On consecutive applications, the pedal height should gradually rise. If the pedal position does not vary, check the booster check valve.

Check valve test:
1. Disconnect the brake booster vacuum hose at the booster.
2. Start the engine and let it idle. There should be a vacuum available. If no vacuum is available, the check valve is not working correctly. Replace the check valve and retest.

END TEST

First, check your brake fluid levels, if it is low then that enplanes your problem. Also, when was the last time you had the brakes changed? if the are worn down, then this will also cause a low fluid level. if the brakes are fine and the fluid level is good and you still have the same issue, then your problem is probably your master cylinder. Brake boosters hardly ever go bad.

You may have a bad booster, but when your brake pedal goes all the way down, you have no fluid, a bad master or really bad calipers

If you haven't already, check your rubber lines for weakness; they could be ballooning under pressure.

the brakes have to be bleed you wrote that when you start the car the pedal goes to the floor that means the booster is working fine take it back and tell them you want the brakes bleed