Nissan Repair: brake booster, 1990 nissan 240sx, nissan 240sx

Question
1990 nissan 240sx l4 2.4

motor runs great,but when brakes applied,kills motor ,i took off the vac line on the booster and it blows stong but is shut under vacuum.?
how do i trouble shoot the brake booster?
thanks chris b

Answer
If the vacuum booster kills the motor when the brakes are applied you must have a blown diaphram.  Basically, plug the hose that goes to the booster and drive the car.  The brakes will be harder to depress but if the engine does not die you have found your problem.  Replace the booster if this is the case.