How to Change Racor Fuel Filters the Right Way — No Mess, No Air in the System | ImpelPro
- 2 days ago
- 4 min read
In this video, marine mechanic Eddie Protzeller walks through how to change Racor fuel filters the right way — without making a mess or introducing air into the system. Many boat owners run into the same issues during this job, including fuel spills, poor priming, or air pockets that cause engine problems. This step-by-step walkthrough shows how to service your Racor filters cleanly and correctly from start to finish.
What You’ll Learn
How to drain a Racor housing before removing filters
Why checking for old O-rings is critical
How to prevent air from entering the fuel system
The correct way to fill the housing and fully submerge filters
How to read a vacuum gauge before leaving the dock
Step-by-Step Overview
Turn fuel supply off
Open drain valve and introduce air to empty the housing
Remove Racor lid and filters
Allow filters to fully drain before handling
Inspect lid for stuck O-ring and remove if present
Install new filters and begin filling housing
Submerge filters completely using controlled fill method
Ensure fuel level covers full filter media
Reinstall lid carefully without overfilling
Check vacuum gauge and restore fuel flow
Mechanic Insight
Racor fuel filters are your first line of defense in protecting your engine from contamination. The biggest issues during filter changes aren’t mechanical — they’re procedural. Failing to drain the housing, missing an old O-ring, or leaving air pockets in the system can create problems that show up later as hard starts, loss of power, or fuel system instability.
Troubleshooting Insights
Why does fuel spill everywhere when changing Racor filters? If the housing isn’t drained before removing the filters, fuel will overflow as soon as the lid is loosened.
Why won’t my engine prime after changing the filter? Air trapped in the system — often caused by improper filling or a double O-ring seal — can prevent proper priming.
What happens if you leave an old O-ring in place? Stacking a new O-ring on top of an old one can allow air to enter the system, causing ongoing fuel issues.
Why is it important to fully submerge the filter? If part of the filter is exposed to air, it reduces filtration capacity and allows air pockets to travel downstream.
What does the vacuum gauge tell you? It shows how hard the engine is working to pull fuel. Rising vacuum levels indicate filter restriction or contamination.
Full Transcript
Eddie: Hey everyone, it’s Eddie from ImpelPro. Today we’re changing out Racor fuel filters.
We’ll start by turning the fuel supply off. Once that’s done, we can begin draining the housing by loosening the drain valve.
If the flow slows down, we can introduce air into the system to help it drain more completely.
One of the biggest mistakes with smaller Racor units is not draining the fluid level enough before removing the filters — that’s what causes fuel to spill everywhere.
Once drained, we remove the lid and allow the filters to continue draining.
With Racor filters, this system is your first line of defense for fuel cleanliness. The filter rating and housing size determine how much filtration capacity you have.
Now let’s talk about the vacuum gauge. This gauge shows how much resistance there is in the fuel system.
If you’re starting to see higher readings — especially under load — it’s a sign your filters may be getting restricted.
Before leaving the dock, it’s important to check where that gauge is sitting at idle and under load conditions.
Once the old filters are removed, we want to make sure everything is clean and ready for reinstall.
One important step — check the lid carefully. Sometimes the old O-ring gets stuck to it.
If you install a new O-ring without removing the old one, you can introduce air into the system and cause priming issues.
Now we install the new filters.
As we begin filling the housing, we want to make sure the filters are fully submerged in fuel.
If they’re not fully submerged, you’ll end up with an air pocket inside the housing, which can travel downstream and cause problems.
We fill the housing gradually, allowing the fuel to soak into the filter media.
You’ll notice the fuel level drops as it gets absorbed — that’s normal.
Continue filling until the filters are completely submerged and the fuel level covers the entire filter.
At this point, we reinstall the lid carefully.
If the fuel level is too high, you may need to drain a small amount to prevent overflow when sealing the lid.
Once everything is sealed and clean, the system is ready to go.
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Topics Covered
racor fuel filter change
racor fuel system maintenance
marine fuel filtration
vacuum gauge reading
preventing air in fuel system
marine engine fuel system troubleshooting
About the Author
Eddie Protzeller is a veteran marine mechanic and the inventor of the ImpelPro impeller puller. With over a decade of experience working on tugboats and yachts, he shares practical, real-world maintenance techniques to help boat owners service their systems with confidence.
Learn more about ImpelPro
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