I have just replaced the front pads on the truck, didn't break into the system just pushed the pistons back, now when I start up when pressed the pedal goes spongy and to the floor. It's fine without the engine running and with the servo pipe clamped. I have also blocked off the master cylinder outlet ports with bleed nippels and that holds pressure when running or not. I have now bled all 4 corners and the situation is the same. Has anyone had this before or got any suggestions? It's an 06 plate. Cheers guys.

New pads on old discs will need to wear to the shape of the disc so the brake pedal gets a spongy feel to it while the wear to shape

It's not a case of pads settling in as the pedal goes to the floor once the engine is running. I have fitted a new master cylinder, replaced the abs twice, bled numerous times. Isolated each line and when the passenger side is concerned the pedal goes to the floor. I have clamped the hoses and they are not ballooning, it's as if the calipers are leaking but they are not, everything was fine until I fitted the new pads.