1989 DeVille bought 4 years ago, brakes seemed ok but realized when winter came that front brakes were doing all the braking. Examined rear wheel cylinders and found stuck solid. Replaced them, but noticed pressure when bleeding was minimal. Got little brake at rear, but not much. MC looked like it had been replaced, but replaced that again anyway. Still low pressure at rear. Lines under car rusty so thought maybe kinked or obstructed, though looking back, that probably unlikely, being this car has separate lines (4) going from MC to each wheel. Car used intermittently since but developed gas line leak which turned into major project. Replaced not only fuels tank, pump, sending unit assembly and all 3 fuel system lines, but also all metal brake lines. So both rear lines new from MC to wheels. Still has low fluid pressure at both rear cylinders. Now wondering if large fittings between MC and rear lines are residual pressure valves are somehow restricting fluid pressure, but ran a bleeder line from one of MC rear brake ports and seems to have pressure up there. Rubber hoses at rear look ok, though front rubber hoses probably should be replaced as covering coming apart where steering motion flexes them. At this point, suspect that isn't going to help rear brake problem though. This is not an ABS system, has rear drums and is FWD car. Ideas?

 

Resolved with a Mity-vac! Replaced front hoses and re-bled using hand pump instead of pumping pedal til the cows come home. Brakes like a new car now. For whatever reason, pumping brake pedal would not create enough line pressure to get all air out, but hand vacuum pump did.