NH 1725-Wouldn't start

I have a 1997? NH 1725. Went to start it the other day and it wouldn't start. Kinda sounded like it wasn't getting fuel. I removed the fuel filter, it looked kind of crumy so I changed it. Opened up the bleeder screw and had fuel at the bleeder screw. I then tried to start it and it wouldn't start. I then loosened the injector line fittings and turned over the motor and nothing. I think I have a blockage in the injector pump or a bad injector pump. My question is how do I check(or clean out) the injector pump. Any sugestions are appreciated. Thanks.