Nissan Repair: serena brakes, spongy brakes, nissan serena

Question
Hi there I have just replaced front brake pads on a
1995 nissan serena as old ones were worn out since I have changed pedal is spongey have bled all brakes corectly no air anywhere if you pump brakes with engine off they are fine but as soon as you start they go to about half or quarter pedal the calipers
seem to be working correctly and sliders arent seized  so cant see what it can be any help would be well apreciated

Answer
Andrew,

If you changed to ceramic pads that could be the problem with the spongy brakes.  Other areas of interest would be the the master cylinder could be going out and that would definately give you soft brakes.  Lastly, use Ford High Performance Brake Fluid to have really firm brake feel.  The fluid has twice the boiling point required and it is still DOT III so it will not screw up anything.  You have to get it from a Ford Dealership and it is worth the five bucks a pint.  I would probably be changing the master cylinder if you have quality factory pads on the car and the brakes are spongey.