Mercury 115 HP Fuel Filter Replacement
A clogged fuel filter starves your 115 hp Mercury 115 HP of fuel — hard starts, hesitation and lost power at speed. Below is the filter we recommend, which 115 HP variants it fits, a step-by-step video, and the symptoms to look for.
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Watch: how to do it (step by step)
How to replace the fuel filter on a Mercury 115 HP
Mercury 75 – 115hp FourStroke Outboard Maintenance: Changing Fuel Filter
Tools Needed
- Rag or towel
- No other tools mentioned
Safety
- Ensure ignition key switch is turned to the off position
- Have a rag or towel ready to capture fuel leaks
Steps
- Place a rag or towel under the fuel filter to catch leaking fuel.
- Push in on the fuel hose release tabs and disconnect the fuel hoses from the fuel filter.
- Install the new fuel filter, ensuring the arrow points towards the engine.
- Securely connect the fuel hoses to the fuel filter using the locking hose connections.
- Visually inspect for fuel leaks while turning the ignition key to the run position, forcing fuel into the fuel filter.
- Repair any found fuel leaks.
Tips
- The video refers users to Mercury's owner's manual or their website for more information on changing the fuel filter on 75 through 115 horsepower outboards.
Which part do I need for my Mercury 115 HP?
For most 115 HP owners the part above (18-7758) is the right choice. Price tip: the aftermarket numbers are usually noticeably cheaper than the OEM-branded box — it is the same physical part. If you need an exact match, these compatible part numbers also fit:
Show all compatible part numbers (10)
| Part number | Description | Fits | |
|---|---|---|---|
| 18-7914 | Fuel Filter for Mercury, Johnson/Evinrude and Suzuki engines. | 115HP | Find on Amazon → |
| 35-822626Q2 | Mercury OEM 35-822626Q2 (replaces Sierra 18-7914) | 115HP | Find on Amazon → |
| 35877761K01 | Mercury OEM 35877761K01 (replaces Sierra 18-7758) | 115HP | Find on Amazon → |
| 35877761Q01 | Mercury OEM 35877761Q01 (replaces Sierra 18-7758) | 115HP | Find on Amazon → |
| 877761K01 | Mercury OEM 877761K01 (replaces Sierra 18-7758) | 115HP | Find on Amazon → |
| 877761Q01 | Mercury OEM 877761Q01 (replaces Sierra 18-7758) | 115HP | Find on Amazon → |
| 778885 | Fuel filter | 115HP | Find on Amazon → |
| 5031411 | Fuel filter | 115HP | Find on Amazon → |
| 35-822626Q04 | Fuel filter | 115HP | Find on Amazon → |
| 16510-87J00 | Fuel filter | 115HP | Find on Amazon → |
Many of these are the same physical part under different brand numbers. Build years are shown where our parts data has them. Where a variant has no years, only the model code is listed. Confirm against your engine plate before ordering.
Frequently asked questions
What fuel filter fits a Mercury 115 HP (115 hp)?
The Mercury 115 HP uses the fuel filter sold as Sierra 18-7758, plus its OEM and aftermarket cross-references (10 compatible numbers are listed above). Confirm the number against your engine's model code and year plate before ordering.
How often should I replace the fuel filter on a Mercury 115 HP?
Replace the fuel filter once a season or per the service manual — and sooner after a batch of dirty fuel or water in the separator.
What are the symptoms of a clogged fuel filter on a Mercury 115 HP?
Hard starting, hesitation or surging under load, stalling at higher throttle and a general loss of power. The engine typically runs fine at idle and starves when fuel demand rises.
Do I need to bleed or prime the fuel system afterwards?
On diesel engines, yes — air must be bled from the fuel system after the filter change, and the video shows the procedure. On petrol outboards, squeeze the primer bulb firm before starting.
How long does a fuel filter change take on a Mercury 115 HP?
Usually 30-60 minutes including priming or bleeding — a straightforward DIY job with basic tools.
Related guides
- Mercury 75 HP fuel filter
- Mercury 30 HP fuel filter
- Mercury 40 HP fuel filter
- Mercury 60 HP fuel filter
- All Mercury maintenance guides
- Free Mercury boat valuation
- Buying a boat? Check whether the asking price is fair
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