I have an 1993 F250 turbo diesel with some brake issues.
It seems that my front brakes will only work if I pump the pedal a few times.
I recently had some work done on them and they were working perfect then one day they just felt like they were not working. There dosnt seem to be any leeks, could it be a master cylinder issue??? my pads rotors and calipers seem good to.

 

could be mc or brake booster

 

If you don't have any leaks, it would be an issue with keeping pressure. If you have drums, it could be at the piston inside them, the caliper pistons can also cause this, and finally yes, the last issue would be your master cylinder. I would throughly check for leaks to be certain, as all three of these tend to leak when this is the issue.

Are any of these parts newly replaced? It could be a defect.

To actually see which one of these parts is causing it, what I would do is cap off the last connector to each of these (one at a time) and check to see if pressure was staying (starting with the newest parts). If none of the actual braking components fail this test, then its most likely your master.

EDIT: Note that the vehicle needs to be running during the "test" phase.

 

thanks I'll check that out

 

Make sure that your rear brakes are fully adjusted up.