brake booster and master cylinder

I went to move my truck yesterday and went to hit the brakes and it drops all the way to the firewall and has no brake pressure at all is the booster and master cylinder the issue?? their is a big car show coming up next month and I want to get it running sooner than that if someone could help that would be awesome thanks guys

First thing I'd do is check to see if the fluid is low, or gone. If it's gone, find the leak.
If there is still fluid in the reservoir, I say bad master cyl.

"First thing I'd do is check to see if the fluid is low, or gone. If it's gone, find the leak."

What SinCity posted. Oftentimes the master cylinder leaks out its rear seal, at the front of the booster. In the 22 years I've had my B2200 the brake master cylinder is way more prone to leak (I've replaced mine at least 4 times) than the front calipers or rear wheel cylinders. If you do have a leak and need to replace something, be sure to flush all the old fluid out at all 3 bleed screws (just one for the rears).

If bad master cylinder, adjust the booster pushrod length if necessary if the bore depth to the MC piston differs on the new MC, to keep the pedal gap.free play the same.

If bad master cylinder, remember to bench bleed the new MC.

Clutch hydraulics on these are also prone to periodic replacement...

there is fluid in the resovoir this time and the pedelis still goin to the firewall so ill probly just replace both of them jus to be safe considering the truck is 27 years old

Yes, the master cylinder can leak internally and deliver "no pedal" and yet not lose fluid externally.

that's what I thought thanks guys for all the help I just wanna enjoy my truck lol

Master cylinder brake hints and tips brake hints brake tips cylinder tips cylinder hints
(1) Bench-bleed the cylinder before installing.
(2) Use a flare wrench for initial loosening and final tightening of the lines.
(3) For brake master cylinder: adjust the booster pushrod length so that the freeplay is the same as the previous master cylinder (measure depth of bores, and adjust the pushrod the difference)
(4) Don't bend the line after it's loose
(5) Thread in the line fitting several turns by hand to avoid cross-threading, get this started before tightening the MC mounting bolts.

And I recommend lifetime warranty cylinders for this model, been through a few in 22 years with my '88.

Check the vacuum hose for a burned through spot where it connects to the intake manifold. If the hose has gone bad you won't develop any vacuum.

alright so i replaced the master cylinder and there no change whats goin on this time please help thanks

and how do you adjust the push rod ?