How to Change Your Mercruiser Water Separating Fuel Filter

An old fuel filter can slow you down. Replace your fuel filter every season or sooner if needed.

Steps

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    Turn off your battery switches or disconnect the boat's batteries.
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    Turn off your fuel supply valve (if equipped).
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    Position a fan to ventilate the bilge and work area.
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    Place some absorbent towels under the filter to catch any spilt fuel.[1]
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    Using a fuel filter wrench, remove the old fuel filter.[2]
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    Pour the old fuel from the filter into a clean white bucket and look for evidence of debris or water in the old fuel.
    • If you noticed a large amount of dirt or water in your old fuel filter, schedule another fuel filter replacement for after your next boating trip.
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    Inspect the filter mount bracket to insure that the old filter O-Ring has been removed.
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    Wipe clean the filter bracket and inspect the surfaces where the o-ring will have to seal.[3]
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    Replace any damaged filter brackets.
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    Open and inspect your new filter.
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    Pour some clean fuel into the filter for easier start-up.
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    Inspect the new filter o-ring and make sure it's properly positioned on the filter.[4]
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    Coat the new o-ring with a little clean motor oil.
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    Spin the new filter onto the filter bracket until hand tight.
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    Use the filter wrench to snug up the filter another 1/2 turn or whatever the filters instructions suggest. Never over-tighten a filter.
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    Clean up any split fuel and clear the area of all fumes.
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    Open your fuel valve.
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    Turn on or connect the boat's batteries.
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    Test run the boat and check for fuel leaks right away.
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Community Q&A

  • Question
    Where is the fuel filter located on a 3.0 Mercury Mercruiser?
    Community Answer
    Community Answer
    The fuel filter is located under the fuel pump. It has a stainless lock wire holding the pressure screw from loosening. You must cut the wire, loosen the pressure screw with a 10 millimeter wrench and then you will be able to sneak the filter bowl out.
  • Question
    How can I make sure fuel is getting to the motor after changing the filter on my boat?
    Community Answer
    Community Answer
    If you have a fuel injected engine, then after installing the new filter, turn the ignition key to the "on" position (not "start") for a few seconds. Listen for the faint whine of the electric fuel pump building pressure. Turn the key off when you hear the pump stop. Turn the key on again. If the fuel pump starts VERY briefly, that means you have filled the filter and the system has pressurized. If the fuel pump runs longer than a second, repeat the off-on cycle a few more times. If your engine is not fuel injected, then consult a local marine mechanic - priming fuel systems on carbureated boat engines is beyond the scope of online DIY advice.
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Warnings

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Things You'll Need

  • New fuel filter.
  • Fuel Filter Wrench.
  • Absorbent towels/rags.
  • Fan.
  • New motor oil.
  • Clean bucket.

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References

  1. ↑ https://goneoutdoors.com/replace-fuel-filter-mercruiser-engine-7270495.html
  2. ↑ https://www.youtube.com/watch?v=r0q1aqDeKbc
  3. ↑ https://www.youtube.com/watch?v=2BdqdWXStJI
  4. ↑ https://goneoutdoors.com/disable-outboard-oil-injection-7865187.html
  5. http://www.sterndrives.com/water_in_fuel.html

About This Article

wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, 14 people, some anonymous, worked to edit and improve it over time. This article has been viewed 129,583 times.
55 votes - 82%
Co-authors: 14
Updated: October 21, 2021
Views: 129,583
Categories: Boats
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