Tips for Keeping Fuel Injectors Clean

Cleaning a boat engine’s fuel injectors is a commonly overlooked maintenance job. Dirty fuel injectors can hinder the motor’s performance or damage it.

Fuel injector cleaning tips

Fuel injectors are electronically controlled valves that pulse open and closed to either prevent or allow fuel to spray into the engine’s combustion chamber and maximize the motor’s power output.

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Stale ethanol fuel deposits turn to varnish within fuel injectors, and tiny pieces of dirt also accumulate within them. Contaminated injectors don’t provide the correct fuel flow to the engine, causing loss of power and performance. The motor’s ECU senses the lack of fuel and compensates by increasing the fuel flow. This causes fuel consumption to increase, while the out-of-balance ratio of fuel-to-air within the motor won’t provide proper cooling. 

Symptoms of Dirty Fuel Injectors

  • Motor fails to start at first attempt or idles roughly
  • Power surges when the throttle is opened
  • Loss of power at WOT
  • Lower top speed and difficulty getting on plane.
  • Increased fuel consumption

How to Clean Fuel Injectors

The best way to keep fuel injectors clean is to prevent them from getting clogged in the first place. Properly cleaning fuel injectors requires specialized kits, and attempting to clean them with makeshift cleaning systems can make them worse.

Fuel injector cleaning process

Cleaning fuel injectors requires testing the injectors’ ohm resistance, dipping them in ultrasonic baths and accurately testing their spray patterns. Because few own the hardware for ohm resistance testing or ultrasonic baths, cleaning fuel injectors is a job best left to the pros.

If the injectors on your motor are several years old, it may be time to replace them with a new set. Replacing fuel injectors isn’t cheap, but the improvements in fuel consumption can more than offset the cost over time.

How to Look After Fuel Injectors

To prevent fuel injectors from getting clogged, you need to keep the fuel system healthy. Any impurities or debris in the fuel system can end up in the injectors, preventing them from working properly.

Fuel injector cleaning tips fuel system

Start by filling up with ethanol-free marine fuel if possible. If you can’t get marine fuel, treat the fuel you have with a stabilizer, which helps prevent breakdown and condensation, both of which lead to corrosion and debris in the system. You can also treat your fuel with a fuel injector cleaner to minimize any varnish buildup.

Fuel injector cleaning tips fuel stabilizer

Regularly servicing the fuel system also helps keep fuel injectors clean. The first line of defense the fuel system has is the fuel filters, so inspect them frequently and replace them if necessary. Also inspect the fuel lines, hoses and couplings for any leaks or damage, and replace them too if needed. Finally, replace any O-rings or gaskets that aren’t resistant to ethanol fuel.

Our sister site produced a great video on how to clean fuel injectors, which you can watch below. The fuel injectors used in the video are for motorcycles, but the process of cleaning them applies to fuel injectors in general.




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