Do You Know What Water Does To Your Fuel & Engine? Find Out How To Protect Your Engine With Fuel Additives.


There are several different reasons why there may be water in your engine fuel, from condensation caused by weather to rain water getting into an open cap. The problem isn’t necessarily why it has got in, although this is definitely something you will want to fix, but it is what damage it will cause to your fuel and engine.

What are the symptoms of water in fuel?

Lower Power

Water being within the fuel of an engine will reduce the efficiency of combustion, resulting in a drop in power produced.

Engine Stalling

Within the engine fuel is compressed, however, should there be water within it it cannot be compressed efficiently. This will result in inefficient or not combustion, leading to the engine stalling due to it stopping functioning.

Juddering Whilst Accelerating

If there is more water than fuel being fed into the engine then misfires will occur resulting in the need to apply extra throttle input than usual. Judders will come as a result of the misfires resulting in a lag of power when the accelerator is depressed, no power to sudden power.

The Engine May Fail To Start

This will occur due to the same described above with engine stalling. Inefficient combustion will lead to the engine refusing to start.

What Problems Will Water In Fuel Create?

Rusting Fuel Tanks

Due to water being denser than fuel and the two fluids not mixing, water will find a resting place at the bottom of the fuel tank. If water is present for a prolonged period of time then rust will begin to appear, with the potential for it to reach other parts of the engine if left long enough.

Injector Failures

These parts of the engine supply just the right amount of fuel to the combustion chamber. If water is present, as it is denser than fuel, it will not be sprayed with ease into the combustion chamber. This added strain on the injector could eventually lead to it failing and the engine will fail to run.

Fuel Pump Failures

As already discussed, water is denser than fuel. Any water within this section of the engine will sit at the bottom, causing rust to form and further damage to other sections of the fuel system due to it being constructed so that it pulls fuel from the bottom of the pump. This will cause water to become an issue in other parts of the fuel system.

Not only this but the motor that runs the fuel pump is cooled down and lubricated by the fuel within the pump. Water will prevent these processes from being efficient and eventually lead to failure due to stress or rust.

Oil Lubrication Issues

If water is present within fuel or engine oil then microbes may form and create sludge-like mixtures that will clog up the engine, rather than lubricate it. Without proper lubrication, the engine cannot run efficiently and in some cases, at all.

If all the above issues were to begin to occur within the engine, then it would only be a matter of time before the engine seized. The resulting problem may range from a simple fuel line flushing to the replacement of the entire engine.

What Fuel Additives Are There To Help Prevent Water Damage?

Here at FAST Exocet, we have produced a selection of fuel additives specifically designed to tackle the challenges water throws our way:

  • Anti-Bug – this fuel soluble biocide and preservative does not add to sludge build-ups, protects against tank and pipe corrosion, eliminates plugging of filters and gauges, and is fully compatible with steels, aluminium, zinc and with polyethylene and polypropylene.
  • Demulsifier – this fuel additive is used either to prevent fuel-water emulsions from forming or as a fuel dehazer to eliminate water haze already dispersed within the fuel. Creates a defined fuel-water interface.


There is a fuel additive to help every scenario. 

For more information or advice on how best to protect your engine and fuel from the effects of water contact us on 01743 761415 or fill in our online form.