Fuel Filter: Testing and Inspection
1. Relieve fuel system pressure by starting engine with fuel pump relay (circuit open relay) disconnected and let run until engine dies, then slowly and carefully remove hose on outlet side of fuel filter. Cover with a clean rag while removing hose, to avoid spraying fuel in your face.
2. Remove filter.
3. Blow air through the filter in the normal direction of fuel flow.
^ Air should flow freely through the filter. If any restriction is felt, replace filter
Also check service records. Replace filter as indicated by recommended maintenance, even if filter appears OK.