Brakes problem 1994 Ford F350 Two Wheel Drive Automatic 90000 miles I have a f350 dually diesel. The brake pedal goes to floor when engin is running. Ok when motor is off. New master cylinder, bench bled, no leaks in system. Full system bled three times, all brakes adjusted and in good condition. The shop I had the work done at has no idea. Save up to $24,507 on one of 4,723 used 2012 Ford F-250 Super Duties near you. Find your perfect car with Edmunds expert reviews, car comparisons, and pricing tools. Oct 27, 2016 · Ford should provide a specification of the parking brake's capacity (perhaps defining that it will hold against the GVW on a slope of x degrees), but I have never found such a statement. Without such a statement, a Ford dealer has no guidance about just how bad your particular brake really is.