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Sierra Marine Fuel / Water Separator Filter
Sierra 18-7920 Fuel / Water Separator - 10 Micron - 1"-12 Thread
The Sierra 18-7920 Fuel / Water Separator is a 10-micron spin-on replacement filter designed for universal marine fuel filtration applications using a 1"-12 thread.
This filter uses the large center-hole configuration and is designed to help remove water and fine contaminants from the fuel supply before they reach the engine.
Sierra 18-7920 cross references popular Mercury, Johnson / Evinrude, OMC, Racor and Fram fuel / water separator numbers listed below.
Thread: 1"-12
Filtration: 10 Micron
Style: Spin-On Replacement
Application: Universal Marine
Specifications
| Specification | Details |
|---|---|
| Manufacturer | Sierra |
| Sierra Part Number | 18-7920 |
| Filter Type | Fuel / Water Separator |
| Filtration Rating | 10 Micron |
| Thread Pitch | 1"-12 |
| Configuration | Large Center Hole |
| Replacement Style | Spin-On |
| Application | Universal Marine |
OEM & Cross Reference Numbers
| Manufacturer / Brand | Part Number |
|---|---|
| Sierra | 18-7920 |
| Fram | CH33APL |
| Johnson / Evinrude Outboard | 771839 |
| Mercury Marine | 35-809099 |
| OMC Stern Drive | 771839 |
| Racor | B32014 |
| Racor | S3214 |
Universal Marine Application
Sierra 18-7920 is a universal replacement fuel / water separator filter for compatible marine filter heads using a 1"-12 threaded filter.
Because this filter is used across multiple marine engine brands and fuel systems, fitment should be determined by the filter-head thread and the existing filter cross-reference number rather than by engine horsepower alone.
This is the large-hole 1"-12 thread style fuel / water separator.
Compare your existing filter number and filter-head thread before ordering. Marine fuel separator filters may look very similar while using different center-hole sizes or thread pitches.
What a Fuel / Water Separator Does
A marine fuel / water separator helps protect the engine fuel system by removing water and particulate contamination before the fuel reaches the engine.
Water can enter a marine fuel system through condensation, contaminated fuel or moisture in the tank. The separator provides an additional stage of filtration before the engine-mounted fuel filter or fuel injection system.
10-Micron Filtration
The Sierra 18-7920 is rated at 10 microns, allowing it to capture fine fuel contaminants while separating water from the fuel supply.
Maintaining a clean fuel / water separator can help reduce the chance of restricted fuel flow and contamination reaching carburetors, fuel pumps or fuel injection components.
When Should a Fuel / Water Separator Be Replaced?
Replacement intervals vary based on engine use, fuel quality and operating conditions. Fuel / water separator filters should be inspected and replaced as part of regular marine engine maintenance.
Replacement should also be considered whenever contaminated fuel or water in the fuel system is suspected.
Common Reasons for Replacement
- Routine annual or seasonal maintenance
- Water found in the fuel system
- Contaminated or stale fuel
- Restricted fuel flow
- Engine fuel starvation symptoms
- Unknown age of the existing fuel separator
- Replacing Fram CH33APL
- Replacing Johnson / Evinrude or OMC 771839
- Replacing Mercury 35-809099
- Replacing Racor B32014 or S3214
Installation Notes
Confirm that the filter head uses the correct 1"-12 thread before installation.
Follow the engine or filter-head manufacturer's installation procedure. Inspect the filter-head sealing surface and make sure the old filter gasket has been completely removed before installing the replacement.
Key Features and Benefits
- Sierra marine replacement fuel / water separator
- Sierra part number 18-7920
- 10-micron filtration rating
- 1"-12 thread pitch
- Large center-hole configuration
- Spin-on replacement design
- Universal marine application
- Replaces Fram CH33APL
- Replaces Johnson / Evinrude 771839
- Replaces OMC 771839
- Replaces Mercury 35-809099
- Replaces Racor B32014
- Replaces Racor S3214
- Helps remove water and contaminants from marine fuel
FAQ
What is the micron rating of Sierra 18-7920?
The Sierra 18-7920 is a 10-micron fuel / water separator.
What thread does Sierra 18-7920 use?
It uses a 1"-12 thread.
Is this the large-hole fuel / water separator?
Yes. Sierra 18-7920 is the large center-hole configuration.
Is Sierra 18-7920 a spin-on filter?
Yes. It is a spin-on replacement fuel / water separator.
What Mercury filter does Sierra 18-7920 replace?
It cross references Mercury Marine 35-809099.
What Johnson / Evinrude or OMC number does it replace?
It replaces 771839.
What Racor filters does it replace?
It cross references Racor B32014 and S3214.
What Fram filter does it replace?
It cross references Fram CH33APL.
Is this filter engine-specific?
No. It has a universal marine application for compatible
filter heads using the correct 1"-12 thread.
How do I know if this filter fits my boat?
Compare the existing filter part number and verify that your filter head
uses a 1"-12 thread. Cross-reference numbers are listed above.
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.
Shipping Policy
- Free shipping on orders over $100 continental U.S.
- 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.
- Parts must be new, unused, and in original packaging.
- Installed parts are not returnable.
- Return authorization is required before sending items back.
Need help verifying the correct fuel separator?
Contact Pro Marine
Phone: 941-721-3000
Searchable Terms
18-7920, Sierra 18-7920, Sierra fuel water separator, Sierra water separator filter, marine fuel water separator, marine fuel filter, 10 micron fuel filter, 10 micron water separator, 1-12 fuel filter, 1 inch 12 thread fuel filter, large hole fuel water separator, spin on marine fuel filter, universal marine fuel separator, CH33APL, Fram CH33APL, 771839, Evinrude 771839, Johnson 771839, OMC 771839, 35-809099, Mercury 35-809099, Mercury fuel water separator, B32014, Racor B32014, S3214, Racor S3214, boat fuel water separator, outboard fuel separator, sterndrive fuel separator
0002507
0771839
18-7920
MAR-FLTHD-10-BK
9-37862
96108
835905-5
835908
856039
857618
9-65800
822189
Sierra Fuel Pump Kit 18-7811
The Sierra 18-7811 Fuel Pump Kit is a rebuild kit designed for Mercury and Mariner inline 6-cylinder 2-stroke outboards. This kit restores proper fuel delivery by replacing worn diaphragms and internal components in mechanical fuel pumps.
Fitment Overview
This Sierra kit replaces Mercury OEM part numbers 66599A1 and 89031A1, along with GLM 40350 and Mallory 9-37756. These part numbers identify a fuel pump family used on Mercury inline-6 engines.
Compatibility
| Brand | Horsepower | Engine Type |
|---|---|---|
| Mercury | 90 HP | Inline 6-Cylinder 2-Stroke |
| Mercury | 115 HP | Inline 6-Cylinder 2-Stroke |
| Mercury | 140 HP | Inline 6-Cylinder 2-Stroke |
| Mariner | 90 HP | Inline 6-Cylinder 2-Stroke |
| Mariner | 115 HP | Inline 6-Cylinder 2-Stroke |
| Mariner | 140 HP | Inline 6-Cylinder 2-Stroke |
These engines use a mechanical diaphragm-style fuel pump associated with the 66599A1 / 89031A1 fuel pump assembly.
Example Model Applications
- Mercury 90HP inline-6 2-stroke models
- Mercury 115HP inline-6 2-stroke models
- Mercury 140HP inline-6 2-stroke models
- Mariner equivalent inline-6 models
These are typical applications. Always verify by matching your OEM part number.
Fits These Serial Ranges
This fuel pump kit is used across multiple Mercury inline-6 engine generations and does not follow a single serial-number break.
Important: Confirm compatibility by matching your existing fuel pump or OEM number to 66599A1, 89031A1, 18-7811, 40350, or 9-37756.
Need the alternate fuel pump kit for a different pump style?
View Pro Marine Fuel Pump Kit 115 (A3 Style)
Part Numbers and Cross References
| Type | Part Number |
|---|---|
| Sierra | 18-7811 |
| Mercury OEM | 66599A1 |
| Mercury OEM | 89031A1 |
| GLM | 40350 |
| Mallory | 9-37756 |
What This Part Is Used For
This kit rebuilds diaphragm-style fuel pumps by replacing worn internal components such as gaskets, valves, and diaphragms. It restores proper fuel flow and pressure to the engine.
- Rebuilds mechanical fuel pump assemblies
- Restores fuel pressure and delivery
- Helps eliminate fuel starvation issues
- Supports reliable engine performance
A failing fuel pump can cause hesitation, stalling, hard starting, or poor acceleration.
System Function and Connections
- System Type: Mechanical fuel delivery
- Pump Type: Diaphragm fuel pump
- Location: Engine-mounted fuel pump assembly
FAQ
What engines does this kit fit?
It fits Mercury and Mariner inline 6-cylinder 2-stroke outboards in the 90HP, 115HP, and 140HP range using the A1-style fuel pump.
What is the difference between this and the A3 kit?
This kit fits the A1-style fuel pump (66599A1 / 89031A1). Some engines use a different pump design that requires the A3 kit.
How do I confirm fitment?
Match your fuel pump number or OEM part number to the cross references listed above.
What are signs of a bad fuel pump?
Hard starting, fuel starvation, hesitation, or engine stalling.
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.
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.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Part Numbers
18-7811, 66599A1, 89031A1, 40350, 9-37756, Sierra fuel pump kit, Mercury inline 6 fuel pump kit, Mercury 115 fuel pump rebuild kit
18-7811
40370
508429
66599A1
89031A1
9-37752
693
9-29109
0307573
0395460
0777484
395460
777484
