What Is a Fuel Water Separator?

Fuel cap on white car

A fuel water separator is a device that works to ensure clean fuel is delivered to the engine. Fuel separators provide effective protection for engines used in automotive, industrial, and marine applications. The separator removes water and solid contaminants from the fuel before it reaches the fuel pump. When the fuel contains a lot of water, it wears off the lubricants from the fuel injectors. By removing contaminants, the device prevents the engine from getting clogged up with solid material. Clean fuel enables the engine to run more efficiently. It also prevents engine failure. Diesel and marine fuel separators are amongst the most common types.

Diesel Fuel Water Separator

These are mostly made of aluminum. Diesel fuel separators are available in various sizes depending on the vehicle type. However, smaller separators need to be drained more often. Diesel fuel usually contains a higher amount of water than gasoline or other fuels. If unfiltered, this water together with dirt detracts from engine efficiency. It also makes driving a more laborious exercise. Unfiltered fuel also contributes to increased engine wear and tear.

Diesel fuel water separators collect filtered water which can later be drained from the engine during routine vehicle maintenance. Most separators have a sensor which lets you know when the water level is getting high. You simply remove the fuel tank drain plug attached to the separator which lets the collected water and dirt flow away. It is best to drain the separator often. If it gets too full it will not work well.

Marine Fuel Water Separator

Plastic or aluminum is the preferred material for marine fuel water separators. These draw out water from the boat fuel which prevents water from getting into the motor. The presence of water in the motor can cause a steam explosion. This would easily damage the boat cylinders including the entire motor. The separator can be part of a primary filter or may be installed as a secondary filter. Separators drain off water in either of two ways. When the separator is part of a primary filter, water may be siphoned off by the filter. The motor gets rid of the waste water along with contaminants through this method.

When the separator is installed as a secondary filter, a siphoning mechanism is used to expel the waste water and contaminants. Water and fuel are pumped into a filter and subjected to a rapid spinning motion. The water and unwanted contaminants sink to the bottom while the fuel remains on top. This is siphoned to the fuel line. The wastewater is eventually drained off as the need arises. Some marine fuel water separators are designed to clean the exhaust system of the boat motor as they drain. These function in collaboration with the exhaust system to clean it along with the fuel. It is best to replace a marine fuel water separator every year.