I'm working on my grandpas 1750d with the Perkins Diesel engine and the fuel water separator runs half empty and shuts the machine down when I get past half throttle machine runs fine at idle but give it throttle or put it under a load and it's like the water separator doesn't stay full any ideas anyone?!
First thing to try is loosen or remove the fuel cap temporarily, you may have an air lock and if the tank can't pull air, the fuel pump can't suck fuel. If it's not the cap/vent, then you either have a clogged suction line, or it's sucking air somewhere between the fuel pickup in the tank and the separator outlet, or both. Check the separator to make sure all the gaskets/O-rings are good and in the correct position for sealing. Check all the lines as much as possible for pinholes, cracks, loose clamps at connections, remove the fuel cap, remove the suction line from the separator and using low pressure blow air back through the suction line that connects to the separator, but DO NOT pressurize the separator, the bowl will likely blow out. Try it. If the suction was clogged, then most likely it will clog again as their is material in the fuel tank that needs removing.