Brake booster

[COLORCRAFT]

I have a 37ford with wilwood 4 wheel disc ,a 7iin booster on the frame when the car is running the brake pedal sticks to the floor,its ok when the cars not running,even hooked up a return spring.Could my booster be bad?

[CPPAaron]

I would recommend possibly having the booster checked. Sounds like the diaphram may have a problem.

[COLORCRAFT]

I replaced the booster and the pedal still holds to the floor,any other suggestions?

[CPPAaron]

try an isolation test on the master. Plug the ports (this would bypass the calipers) and see if the pedal still drops. If it does not the re-introduce the rear section in first (leaving the front bypassed) and check.