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Mercury Outboard Parts

Shop OEM and aftermarket Mercury outboard parts for maintenance, repair, troubleshooting, and complete engine rebuild projects. Browse Mercury marine parts by system, including cooling, fuel delivery, electrical and ignition, internal engine components, lower unit parts, steering, trim, and routine service items.

Pro Marine USA carries Mercury outboard engine parts for a wide range of 2-stroke, FourStroke, EFI, Optimax, Pro XS, SeaPro, and Verado applications. Use your engine horsepower, model, serial number, or OEM part number whenever possible to confirm fitment before ordering.

Shop Mercury Outboard Parts by System

Find the Correct Mercury Outboard Part

Mercury outboard parts can vary by horsepower, engine family, model year, and serial number range. If you are unsure which component fits your engine, use the OEM parts lookup to locate the original Mercury part number from an engine diagram.

Once you have the OEM part number, search Pro Marine to find available genuine Mercury and aftermarket replacement options.

Use Our OEM Parts Lookup »

Common Mercury Outboard Engine Families

Pro Marine supports many Mercury outboard applications across a wide horsepower range. Always confirm the engine serial number and model information before ordering parts.

  • Portable and Midrange: Mercury 2.5HP through 60HP 2-stroke and FourStroke applications
  • FourStroke and EFI: common 75HP through 300HP Mercury EFI and FourStroke platforms
  • Pro XS: performance-oriented Mercury Pro XS outboards across multiple engine families
  • Optimax: direct-injected 2-stroke Mercury Optimax engines, commonly 75HP through 250HP
  • Verado: supercharged and naturally aspirated Mercury Verado applications from 135HP through current high-horsepower platforms
  • SeaPro: commercial-duty Mercury SeaPro outboards used in professional and high-hour applications

Common Mercury Outboard Repair Areas

  • Overheating: inspect the water pump, impeller, thermostat, poppet valve, cooling passages, and related cooling components.
  • Hard starting or rough running: inspect fuel pumps, filters, injectors or carburetors, spark plugs, coils, sensors, and intake components.
  • No spark or intermittent ignition: check ignition coils, stators, switch boxes, trigger assemblies, sensors, grounds, and wiring.
  • Low compression or power loss: inspect pistons, rings, cylinders, bearings, gaskets, reeds, and internal engine components.
  • Lower unit noise or water intrusion: inspect seals, bearings, gears, shafts, bearing carriers, and gear lube condition.
  • Trim or steering problems: inspect trim motors, pumps, hydraulic components, steering cylinders, hoses, and related rigging parts.

Why Buy Mercury Outboard Parts from Pro Marine USA?

  • OEM Mercury and aftermarket replacement options for many common applications.
  • Parts for maintenance, repair, engine rebuilding, lower units, electrical systems, fuel systems, steering, trim, and rigging.
  • OEM diagram and part-number lookup tools to help identify the correct part before ordering.
  • Dealer pricing available for qualified marine repair businesses and dealers.
  • Large inventory of Mercury service parts and hard-to-find marine engine components.
  • Fast weekday shipping on qualifying in-stock orders.

Frequently Asked Questions

How do I find the correct Mercury outboard part?

Use the engine horsepower, model, serial number, and year whenever available. Mercury frequently uses serial-number ranges to identify engine families, so the serial number is often the most reliable way to confirm fitment.

Can I search Mercury parts by OEM part number?

Yes. Enter the Mercury OEM part number into the Pro Marine site search to locate available OEM and aftermarket replacement options. If you do not know the part number, use the OEM parts lookup first.

Do Mercury outboard parts vary by serial number?

Yes. Many Mercury components change by serial-number range even within the same horsepower or model family. Always compare the serial range listed for the part with your engine before ordering.

Do you carry parts for Mercury Optimax and Verado engines?

Yes. Pro Marine carries parts for many Mercury Optimax, Verado, Pro XS, EFI, FourStroke, and SeaPro applications, including maintenance, fuel, electrical, cooling, internal engine, lower unit, steering, and rigging components.

Do you carry both OEM and aftermarket Mercury parts?

Yes. Pro Marine offers genuine Mercury parts along with aftermarket replacement parts for many common Mercury outboard maintenance, repair, and rebuild applications.

What Mercury outboard parts are commonly replaced during routine maintenance?

Common maintenance items include engine oil, oil filters, fuel filters, spark plugs, water pump kits, impellers, thermostats, gear lube, drain plug seals, anodes, and manufacturer-specific service kit components.

Fitment Tip: Mercury outboard parts often vary by serial-number range. Confirm your engine serial number and OEM part number whenever possible before ordering.

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OEM Sensor for L6 Verado, 350-425HP V10, 450R-500R V8 & 500-600HP V12

OEM Mercury Water-In-Fuel Sensor

Mercury Water-In-Fuel Sensor 8M0157779 For Verado, 450R, 500R, V10 & V12

The Mercury 8M0157779 water-in-fuel sensor is an OEM Mercury fuel system sensor used with compatible Mercury water-separating fuel filter assemblies.

This sensor fits select L6 Verado applications, Mercury Racing 450R and 500R V8 outboards, Mercury 350HP-425HP V10 outboards, and Mercury 500HP-600HP V12 outboards.

Compatible Applications

Engine Family Horsepower / Model Engine Platform Application
Mercury Verado L6 Verado Models Inline 6-Cylinder Verado Water-in-fuel sensor
Mercury Racing 450R, 500R V8 FourStroke Water-in-fuel sensor
Mercury Verado / FourStroke 350HP-425HP V10 FourStroke Water-in-fuel sensor
Mercury Verado / SeaPro 500HP-600HP V12 FourStroke Water-in-fuel sensor
Important Fitment Note:

This Mercury 8M0157779 water-in-fuel sensor is used on select L6 Verado, 450R-500R V8 Racing, 350HP-425HP V10, and 500HP-600HP V12 outboard fuel filter applications.

Always verify your engine model, fuel filter assembly, and current sensor number before ordering.

Part Numbers & Cross References

Brand / Source Part Number
Mercury Marine 8M0157779
Related Fuel Filter 8M0166596

Related Fuel Filter

What This Water-In-Fuel Sensor is Used For

The Mercury 8M0157779 water-in-fuel sensor monitors the fuel filter assembly for water accumulation and helps alert the operator when water is detected in the fuel system.

Water contamination can cause poor performance, corrosion, injector problems, and fuel system damage. Replacing a damaged or faulty water-in-fuel sensor helps maintain proper warning system function.

Key Features and Benefits

  • OEM Mercury water-in-fuel sensor
  • Fits select L6 Verado applications
  • Fits Mercury Racing 450R and 500R V8 outboards
  • Fits Mercury 350HP-425HP V10 outboards
  • Fits Mercury 500HP-600HP V12 outboards
  • Used with compatible Mercury water-separating fuel filter assemblies
  • Helps detect water accumulation in the fuel system
  • Pairs with Mercury fuel filter 8M0166596 on compatible applications

Part Details

  • Part Number: 8M0157779
  • Product Type: Water-In-Fuel Sensor
  • Brand: Mercury Marine
  • Application: Mercury Verado, Racing V8, V10, and V12 fuel systems
  • Common Fitment: L6 Verado, 450R, 500R, 350-425HP V10, 500-600HP V12
  • Related Fuel Filter: 8M0166596
  • OEM Mercury Part: Yes

FAQ

What engines does Mercury 8M0157779 fit?
This sensor fits select L6 Verado applications, Mercury Racing 450R and 500R V8 outboards, Mercury 350HP-425HP V10 outboards, and Mercury 500HP-600HP V12 outboards.

Does this fit the Mercury 500R?
Yes. Mercury 8M0157779 is used on compatible Mercury Racing 500R V8 fuel filter applications.

Does this fit Mercury V10 outboards?
Yes. This sensor fits compatible Mercury 350HP-425HP V10 outboards.

What fuel filter goes with this sensor?
The related Mercury water-separating fuel filter is part number 8M0166596, linked above.

What does a water-in-fuel sensor do?
It detects water accumulation in the fuel filter assembly so the engine warning system can alert the operator to fuel contamination.

Is this a genuine Mercury part?
Yes. This is an OEM Mercury Marine water-in-fuel sensor.

Dealer Discounts & Store Policies

Dealer / Marine Industry Discounts

Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.

Apply for a Dealer Account

Shipping Policy

  • Free shipping on orders over $100 continental U.S.
  • Orders ship via UPS, USPS, and FedEx.
  • Orders received before 5:30 PM EST ship the same business day.
  • Typical delivery time is 1-5 business days.

30-Day Return Policy

  • Returns accepted within 30 days of delivery.
  • Electrical sensors must be new, unused, and uninstalled.
  • Installed or fuel-contaminated sensors are not returnable.
  • Return authorization is required before sending items back.

Need help with a return or order question?
Contact Us
Phone: 941-721-3000


Searchable Terms

8M0157779, Mercury 8M0157779, Mercury water in fuel sensor, Mercury water-in-fuel sensor, Mercury fuel filter sensor, Mercury Verado fuel sensor, L6 Verado water in fuel sensor, Mercury 450R water in fuel sensor, Mercury 500R water in fuel sensor, Mercury Racing fuel sensor, Mercury V8 water in fuel sensor, Mercury V10 water in fuel sensor, Mercury V12 water in fuel sensor, Mercury 350HP V10 fuel sensor, Mercury 400HP V10 fuel sensor, Mercury 425HP V10 fuel sensor, Mercury 500HP V12 fuel sensor, Mercury 600HP V12 fuel sensor, 8M0166596, Mercury water separating fuel filter sensor

Item#:
8M0157779
Cross Reference#:
8M0157779
Manufacturer Item:
8M0157779
Manufacturer:
Mercury Marine
Available:
In Stock
Your Price:
64.99
Each
Mercury 2.5L 150-225HP Pro Max 1992 & Up 3.500 Bore
Item#:
9500R
Cross Reference#:
840684A12
Manufacturer Item:
840684A12
Manufacturer:
Pro Marine
Available:
In Stock
Your Price:
61.15
Each
Mercury 2.5L 150-225HP Pro Max 1992 & Up 3.530 Bore
Item#:
9530R
Manufacturer:
Pro Marine
Available:
In Stock
Your Price:
61.15
Each
Mercury 2.5L 150-225HP Pro Max 1992 & Up 3.515 Bore
Item#:
9515R
Manufacturer:
Pro Marine
Available:
In Stock
Your Price:
61.15
Each
Mercury Inline 40-60hp Bore Size 2.905
Item#:
3930
Cross Reference#:
18-3917
18-3917
509406
88392
88392A12
Manufacturer Item:
88392A12
Manufacturer:
Pro Marine
Available:
In Stock
Your Price:
21.58
Set
Mercury Inline 20-60hp Bore Size 2.565
Item#:
3903
Cross Reference#:
18-3903
27841
27841A12
Manufacturer Item:
27841A12
Manufacturer:
Mercury Marine
Available:
In Stock
Your Price:
24.37
SET OF 3
Mercury Inline 35-150hp Bore Size 2.875
Item#:
3902
Cross Reference#:
18-3902
18-3902
45155A12
509398
78816A12
9-54217
Manufacturer Item:
78816A12
Manufacturer:
Sierra
Available:
In Stock
Your Price:
54.59
Set
Item#:
0100K
Manufacturer:
Wizard Performance
Available:
In Stock
Your Price:
294.64
Each
Mercury 70-115hp L3 L4 1987-91
Item#:
2616
Cross Reference#:
14930
18-3981
9-54231
96170A4
Manufacturer Item:
39-96170A 4
Manufacturer:
Mercury Marine
Available:
In Stock
Your Price:
12.24
Pair
Mercury 70-115hp L3 L4 1987-91 Bore Size 3.390
Item#:
2614
Cross Reference#:
14920
14920
18-3980
18-3980
96170A3
96170A3
Manufacturer Item:
96170A3
Manufacturer:
GLM
Available:
In Stock
Your Price:
32.24
Pair
Mercury 70-115hp L3 L4 1987-91 Bore Size 3.375
Item#:
2612
Cross Reference#:
14910
14910
18-3979
18-3979
200-25
9-54229
96170
96170A12
Manufacturer Item:
96170A12
Manufacturer:
Sierra
Available:
In Stock
Your Price:
44.19
Pair
Mercury 200-300 EFI DFI 3.0L
Item#:
2581
Cross Reference#:
10-2581
516-38
825815
825815
Manufacturer Item:
825815
Manufacturer:
Pro Marine
Available:
In Stock
Your Price:
4.19
Each
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