Un screw the primer pump and pump it a couple times to see if theirs fuel leaking around the primer piece ,youll need a new one if it is ,possible air leak coming into the fuel supply .
When you changed your fuel filters you might check to see if you had black like pellets in the filters,these are from an algea that grow in diesel fuel after it sits ,the reason their small pellet shaped is they get pulled thru your tank screen.The remedy is to get an alghea killer from your local boat supplier ,theyll carry a startron product that you dump in your tank in recommended amounts per gallon of diesel .This is easy to identify by just dumping the remainder fuel out of your filers into a container a see if the small black pellets are their.Starves your fuel supply at either the tank screen are later when it cloggs your 2nd or primary filter. good luck