Brake Issue need help A.S.A.P

Hey all i got a 1990 single cab 2.2l Diesel bravo and i have a issue with my brakes .

at first i thought it was the master so i got a new one but still the problem is there i have replace the rear wheel cylinders too now the problem is that when the car is running the pedal go's flat to the floor but if you pump it a few times it comes good but if the car is off the pedal is firm so when vacuum is turned on i get a soft pedal , there is no air in the lines i used 1.5l of brake fluid to make sure there was no air

only thing i can think of is the booster or vac pump ??? ideas ???

oh and when you pump the pedal with the car on the little brake light flashes any idea why that is ? is it because the brakes aren't working right ?

thanks in advance for any help given if you need more details i will provide them to the best of my knowledge

Really , no one can help ??? i find that hard to believe

Does the truck have abs? If so that could be a symptom of abs problems. You said the brake light was on, was it the abs light?

Are the rear brakes adjusted properly?

+1

You wouldn't think it necessary but make sure the back brakes are adjusted first, then do the rest including bleeding the system...

for some reason the system on these trucks needs the back brakes adjusted first....

i think they are how do i tell ?, i took the truck for a quick drive up the road before and the brakes work really well but if you hold your foot on the brake the pedal still sinks to the floor the same as if the trucks not moving

As far as telling if they are adjusted or not pull out the parking brake lever, I have always gauged my rear brakes by the number of clicks you feel before the lever gets hard to pull. My truck is set at 4 clicks out.

Mine takes a lot more then that ill check when I get home from work but I'm going to guess n say its about 10 clicks so I'm going to say there not adjussted very well .

it takes 14 click of the hand brake before it gets hard to pull

That's a lot. First adjust the rear brakes manually, then adjust the handbrake cable if necessary.