A fuel filter works to maintain a boat's engine fuel system. It keeps dirt and rust from the fuel so it doesn't get contaminated and cause damage to the injectors and engine pumps. It's important to keep contaminants at bay because these particles can also affect fuel efficiency.
Types of fuel filters
There are three main fuel filter types: the pretank filter, primary and secondary filters. The pretank filter looks like a funnel and is designed to provide basic filtering as fuel is poured into the tank. It is the first component that cleans fuel of large contaminants such as leaves, plastic bits and dirt. The pretank filter is made for cruisers that travel to areas where fuel is scarce and typically comes from used drums.
The primary filter, on the other hand, is a form of after market filter. You can add this to your fuel system later on. It is composed of a number of units and comes in different fuel filter types including the spin-on element and the independent mount. The former is a filter that is similar to what you would normally use for cars. It is suitable for boats that run on gasoline. On the other hand, the independent filter is mainly designed for diesel engines.
Finally, there is the secondary filter. Among the fuel filter types, this is considered the least common. Given that your primary filter system is already efficient in keeping contaminants off, you don't really need to get a secondary filter. In any case, this is just a canister-type accessory that you can mount directly onto your diesel engine.
If you're in the market for a good fuel filter, you want to make sure that the product is sized according to its flow rate.