Fuelpro 321

Only thing I can think of would be to keep guys from pre-filling the filters. Ever since going electronic the fuel system pressures have been getting steadily higher and the fuel system components have been getting tighter and tighter tolerances. Most manufacturers these days don't recommend pre-filling anymore because the risk of damage from contamination is very high.

 

Your fuel pro 321 is supposed to have a clear glass dome. In an emergency if that plastic clear glass dome breaks you can screw a normal fuel filter on there to get you home.

Get a proper replacement for it and get rid of that spin on filter. Its not designed for it. Even the water drain is on the top. Should of been your first clue.

 

Supposed to look like this.