Vital Fluids
Diesel engines need an uninterrupted, air- and water-free supply of clean fuel to run. However, a long list of gremlins can prevent the fuel supply in the tank from reaching your engine in purest form.
Let’s talk about the fuel system and some of the problems that can occur from attrition and error.
The Fuel Supply
Your boat’s fuel supply system can be installed from the top or bottom of the tank.
From the top, the fuel leaves the tank via a pickup tube that extends to within a half-inch of the bottom. Some manufacturers put a screen on the bottom of the tube to keep things out of the fuel system; that screen can become plugged from debris or from the emulsion that forms when water and fuel mix in the tank. If the screen is blocked, then the pickup tubes must be removed from the tank. Removing those tubes is easy if there is good access to the top of the tank, but it’s not a job to do in a rough seaway. Without the screen, any debris will be captured in the fuel filter, where it can be easily removed with a filter change.
Bottom-feeding tanks use a threaded bung near the
