My friend Jim used to work on seagoing tugs and whatnot; big boats. He and I were out fishing aboard his old 28' Bayliner with a Yamar 27 HP diesel outboard and I noticed how he did the fuel filter. Installed AFTER the filter is a vacuum gauge. A casual glance shows you how much strain the engine fuel pump is using to suck fuel from the filter. If the gauge is reading higher than normal, Jim can clean the filter. This costs about $75 for the gauge but is well worth it as it makes it highly unlikely you'll ever have a filter clog up and stop you. It's so sensible, I'm still surprised it isn't typically installed on all boats!