Suicide brake - 1971 Series III

I recently removed the front axle to work on the frame, which meant disconnecting the front brakes for about a year. During the rebuild I also replaced the master cylinder. Everything is now back together. (Non Servo - Drums all round)

Here’s the problem:

• I bled the brakes using the sequence (furthest to nearest), pushing about 1.25 liters through.
• When I pump the pedal a few times, it firms up and the brakes engage normally.
• But if I release the pedal and press it again, it goes straight to the floor with zero resistance—as if the line is cut and there are no brakes at all.
• Repeating the cycle, it firms up again after a few pumps, then immediately loses pressure once released.

Most advice I’ve seen says keep bleeding because Land Rover brakes can be tricky. But given these exact symptoms, is there something specific I should focus on?

88 inch model?

Adjustment or you have fitted the return springs incorrectly, which is quite common and easily done.

Try clamping off the flexi hoses at the front wheels and at the back axle and see what pedal feels like then.
Then release one at a time and you will see where the problem is

Clamp both front flexi pipes, bleed and adjust rear brakes until they work well.
Then clamp the rear, bleed and adjust the front brakes until working well.
Obviously you need to be careful test driving with the front or rear brakes clamped off.

i used to have that issue many years back i assumed i never needed to adjust the brakes and id think the master cylinder was bad as i had to pump two to three times to build up pressure but then i found out that yes the snail cam adjuster needs to be done up so you feel ever so slight resistance and the brake pedal maybe only goes down half way, i got the early non servo type you get used to no servo and to pull up quicker you just push on the pedal harder, its odd when you get in modern cars and the brakes need no effort at all, i had a friend years ago try to drive the car and he was like wheres the brakes i said you gotta push some pressure on the pedal,

i got a friend that has a Perentie ex aus army landrover and i tell you now his clutch is even heavier then trying tp pull up a series landrover real quick and he is 75 i said that clutch is so damn hard it aint funny, one of his knees is bad and i said thats probably due to the clutch pedal having such a heavy duty clutch fitted he has a heavy spring set on the pressure plate as it runs the Isuzu 3.9 diesel, that engine puts out a ton of torque its mated to a lt95 as standard to help with the engine torque. he can easily pull 4 ton trailer with no effort at all he has claimed.
i got a pic of it pulling the trailer in question.
he i running 130 defender rims on it with arivo m/t tyres, its his daily drive the local 4x4 club used to give him a hard time as he is the only landrover there the rest have all jap vehicles, which yeah lets say dont pull that trailer very well but enough of going off subject too much.