2000 Dodge PU brakes

My buddy got a vehicle, brakes went out, he put a new caliper, rotor and pads on one wheel, pads on the opposite wheel. A new power booster was installed and brakes bled with engine off. Brake pedal pumps up good, has brake but after pedal returns and he applies brake again, the pedal goes to the floor. I helped him bleed the brakes and see no signs of air in the lines. HELP

Ok there four things that could have went wrong you have to work through
them in logical order.
Here are 6 different tests in some sort of order .
(1) The first thing to do is go round all the unions, hoses and bleed nipples with a lamp while hard pressure is applied to the system. You are looking for the tiniest trace of fluid, look very carefully. The reason for this you can get a one way leak where almost no fluid leaks out but air is drawn back into the system on the return stroke of the pedal.
(2) A very quick simple test is to get your friend to pump the pedal on and off hard while you go round each wheel and listen for any unusual creaking noise that my point excess mechanical movement. If you actually hold each caliper while this is being done you can sometimes feel excess movement in the caliper.
(3) The next simple test is looking for a faulty seized caliper or a drum brake self-adjuster that is slipping back. You can do this by off clamping each rubber flexible brake hose in turn and test the brake pedal travel. Ideally you should use a proper brake hose clamp (sometimes called a hose nip or hose pinch) but with (great) care you can use a pair self locking grips but pad the jaws with several layers cloth to avoid damaging the rubber hose.



Strange as it may seem a brake caliper with seized piston or guide pin will give long pedal travel with a distinctive feel more springy feeling than spongey.

(4) The next test is for "sinking pedal" which is usually a master cylinder fault. With the engine running put very gently pressure on the brake pedal if the pedal gradually sinks to the floor you are 100% sure there are no leaks anywhere in the pipe work, hoses or cylinderss then it points to a master cylinder seal fault.

(5) Another master cylinder test is fill the cylinder to the brim and get your friend to work the pedal both gently as above and hard on off. You are looking for changes in fluid or bubbles in the fluid.

(6) If you think you have a faulty master cylinder the way to be 100% sure is to disconnect each pipe at the master cylinder and replace it wth a suitable bleed nipple -- then a quick bleed and then when you test the pedal it should be very hard. Remember to reconnect and bleed the pipes before driving off.

---

For some years now I have used a pump up pressure brake bleeder as some brake master cylinders are very difficult to bleed by the old style pedal pumping method and vacuum bleeders sometimes pull air into the system past the rubber seals.

Thank you so much Andy. My buddy has decided to pull the back wheels off and check them. He has excess noise back there when we applied the brakes. I appreciate your speedy response and your detailed explanations. I'll let you know what we come up with. Thanks again.