Pedal goes to floor after backing up

[polarzak]

My 2000 Lesabre has a interesting problem. The brakes work fine, until the car is backed up. The reverse movement is stopped normally by pressing the brake pedal, put the car in DRIVE and and the brake pedal goes to the floor when the brakes are applied. Pumping the pedal once or twice restoers normal braking. I will have normal braking until the next time I have to reverse, and then go forward, pedal goes to the floor.
I have inspected the front and rear pads and rotors, no leaks, and the resevoir is full of fluid. There are no warning lights. Anyone have an idea before I take this to the dealer and have my wallet extracted through my nose.

[s426]

hi
check for vacum leak, booster. see if you getting a good vacum.it could be leaking inside booster.you have to keep an eye on fluid level,

[polarzak]

Originally Posted by s426

hi
check for vacum leak, booster. see if you getting a good vacum.it could be leaking inside booster.you have to keep an eye on fluid level,

Thanks for the reply. I suspect it has to do with the vacume, I just don't understand it only happens after I reverse the car. I could drive
a zillion miles forward, and no problem. Once I put the car in reverse,
the next time I go forward, pedal to the floor. Pump it a few times and all is good. Fluid is normal. Beats me, so I booked an appointment next
week with the dealer. I will probably be told it is the booster, and they have to go through the trunk to remove the engine so they can remove and replace it. New fangled cars have made anything difficult to repair. Geez, I wish I had my 69 Goat again. Easy to work on. Thanks again.