Weird results during and after bleeding brakes

I am helping out a friend get his 82 ford econoline, back on the road after sitting for 2 or 3 years. We checked the fluids before starting or moving. After starting it and moving it the brake peddle went down quite far and also felt spongy. So we bled the brakes, of course starting at the passenger side rear and working our way around to the drivers front. We were getting what I thought were weird results, starting On the first bleed, it went as it should... it pushed out some air bubbles with the fluid, and the peddle fell as I opened the valve, as it should. Then I had him push on it again, and the peddle went almost to the floor, so he pumped and pumped and it wouldn't come back up, then after a couple of minutes he pushed on it again and it was firm and up where it should be. So I had him push on it again while I opened the bleeder screw, only this time hardly any fluid came out and the pedal didn't drop, even with him pushing hard. I don't understand why one time it will push out the fluid, but the next time it will not. Also the feel of the pedal, why won't it build up pressure when pumping it right after opening and closing the bleeder? but if I wait about one minute and then pump the pedal it will come right back as it should. Both rear brakes are doing that but the front ones bleed as they should. Also the brake light will go off after bleeding, but then come back on after driving a mile or two.

I can't find any type of fluid leak in the system.

I am at a loss! We have twice bleed the brakes, doing 4 rounds at each bleeder, and each time after driving it a few minutes, it goes right back to having a spongy pedal and is hard to stop.

Could it be the combo/Proportioning valve? or the master cyl? Or???

Any suggestions, advice, ideas and/or thoughts are greatly appreciated!

geezzz Thanks for all the help!

now incase anyone else has this type of a problem, maybe MY findings might ACTUALLY HELP someone else.

I removed the right rear drum, to find that the adjuster mechanism was completely destroyed, along with a couple of the return springs. I replaced the shoes, and all the hardware.. and now we have a firm pedal and good brakes!


Thanks for the help azdesert rat!

Why, your more than welcome azdesert rat!