Why Add Fuel Stabilizer Every Time You Fill Up 

Fuel system problems are a common complaint among outboard engine owners. 

Marine fuel stabilizer fill up

Fuel injectors, carburetors, pumps, rails and lines are delicate components, and a tankful of bad fuel can easily clog, corrode or damage them. The simplest way of ensuring your outboard’s fuel system is in good shape is by adding fuel stabilizer to the tank every time you fill it up. Adding fuel stabilizer at every fill-up might seem excessive, but it certainly doesn’t hurt. Here’s a guide to adding marine fuel stabilizer to your outboard’s fuel.

Fuel Stabilizer plus Ethanol Fuel

Most fuel these days contains 10% ethanol (E10 fuel). While this is great for the environment, it’s not so great for your outboard’s fuel system. 

Marine fuel stabilizer water ethanol

Ethanol is hygroscopic and hydrophilic, meaning it attracts water molecules and absorbs them. Eventually the volume of water reaches saturation point, at which time “separation phase” occurs, the water/ethanol mixture separates from the gasoline and forms a layer on the bottom of the fuel tank.

Outboards draw fuel from the base of the tank, and this water/ethanol mix is pumped through the fuel system, preventing the outboard from running and requiring the system to be stripped and cleaned. It’ll probably require a few parts to be replaced as well, which of course costs money.

Adding marine-spec fuel stabilizer slows down the rate water is absorbed into the fuel, thus reducing the possibility of phase separation. Even if you run your outboard often and burn through a tank of fuel quickly, there’s always some older fuel left in the tank when you fill up. Any unused fuel will already contain some absorbed water, which increases over time.

PRO TIP: Never let the fuel tank get lower than approx. 20% from empty, or else you run the risk of floating debris within the tank being drawn through the fuel system, where it’ll clog fuel injectors or carburetors.

Fuel Stabilizer plus Marine Fuel

Even if there’s a local vendor who provides ethanol-free marine fuel (E0 fuel) and you can afford it, you should still add fuel stabilizer when refueling your boat.

Marine fuel stabilzer refueling

All gasoline types have an extremely short shelf life before rapidly deteriorating. This degradation can begin in as little as 30 days. As gasoline oxidizes, it becomes less combustible, which puts additional stresses on an outboard’s pistons and cylinders as the combustion process becomes erratic. This poor combustion also stresses many other components within the motor as it struggles to operate.

Adding marine fuel stabilizer to E0 marine fuel prevents it from deteriorating and ensures it’ll combust well, thus reducing undue stresses on the outboard.

Use marine fuel stabilizer even if you run your boat frequently enough to quickly consume a tank of fuel. After all, the fuel may be new to you when you fill up, but you don’t know exactly how long it sat in the vendor’s dockside tank before you pumped it into your engine.

Fuel Stabilizer and Storage

Over time, gasoline breaks down and leaves behind gummy deposits that can easily clog fuel injectors, pumps, rails and carburetor jets. To prevent this, always fill your fuel tank before storing your boat and add a fuel stabilizer. Run the outboard for a few minutes to draw the stabilized fuel through the fuel system. This ensures the fuel within the system won’t break down and gum up precision parts from within.

Which Fuel Stabilizer to Use

Outboard manufacturers make OEM fuel stabilizer, but there are plenty of well-known aftermarket brands available as well. Read your outboard’s service manual and the fuel stabilizer’s label instructions to determine which product is best. Popular marine fuel stabilizers include:

These fuel stabilizers and countless other essential boat maintenance supplies are available right here at Boats.net!



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