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Fuel & Water Sensor 8M0021043 – Mercury Outboards / Zeus
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How to Match This Part
This aftermarket fuel and water sensor (water-in-fuel sensor) replaces Mercury 8M0021043 and the earlier number 889330. It installs in a water-separating fuel filter assembly and signals water contamination in the fuel. Mercury also lists 8M0214989 as the later functional replacement for 8M0021043.
Match this part in this order:
1. OEM number on the sensor or in your parts list — 8M0021043, 889330, or 8M0214989
2. Serial number on the Mercury outboard mounting bracket / cowl plate, or Zeus identification plate
3. Engine model against the Compatible Engine Models table below
This listing is new production, not remanufactured. Compare the product images to your original sensor before ordering — connector and lead layouts can vary across supersessions.
Part Number Cross-Reference
Use this table to confirm equivalent Mercury part numbers in the verified supersession chain.
| Type | Brand | Part Number | Notes |
|---|---|---|---|
| OEM | Mercury / Mariner | 8M0021043 | Primary listing number (Fuel and Water Sensor Assembly) |
| OEM | Mercury / Mariner | 889330 | Former number; superseded by 8M0021043 |
| OEM | Mercury / Mariner | 8M0214989 | Later functional replacement for 8M0021043 (may look different) |
This is an aftermarket part manufactured by JLM Marine and is not sold as a genuine Mercury Marine component.
Compatible Engine Models
Confirm your engine model and serial number in the table below. For Mercury owners: Mercury Serial Number Guide and Mercury Parts Diagrams. Coverage is limited to applications that call for 8M0021043 / 889330 / 8M0214989 — do not assume every 75–400 HP Mercury uses this sensor.
| Engine Model | HP | Serial Number Range |
|---|---|---|
| 75 / 80 Jet / 90 / 115 / 125 DFI (3 cyl. 1.5L) | 75–125 | 1B736885 & Up (115 Pro XS: 1B751825 & Up) |
| 135 / 150 / 175 / 200 Verado (4-Stroke 4 cyl.) | 135–200 | 0P514869 & Up; also 1B517159 & Up |
| 200 / 225 / 250 OptiMax & Pro XS DFI (3.0L) | 200–250 | From 1B504989 / 1B528615 / 1B752547 & Up (per model) |
| 200–300 Verado / Pro Verado (4-Stroke 6 cyl.) | 200–300 | Ranges including 0P520553–2B144122 and 2B144123 & Up |
| 350 / 350SCi / 400 Verado & Pro Verado (6 cyl.) | 350–400 | 350SCi 1B716557–2B143542; 350/400 from 2B141124 / 2B141617 & Up |
| Zeus 3000 | Pod | Selected serial blocks (0M968828 series) and 0M969003 & Up |
Technical Specifications
| Specification | Value |
|---|---|
| Part type | Fuel and water (water-in-fuel) sensor assembly |
| Primary OEM number | 8M0021043 |
| Supersedes / related OEM | 889330 (former); 8M0214989 (later replacement) |
| Function | Detects water in fuel at the water-separating filter and signals the monitoring system |
| Approx. overall size | 7.25 in L × 1.00 in W × 0.63 in H |
| Condition | New production (not remanufactured) |
Installation Guide
1
Stop the engine and disconnect the battery. Relieve fuel-system pressure per the Mercury service procedure for your model.
2
Locate the water-separating fuel filter that uses this sensor. Unplug the sensor connector and note wire routing.
3
Remove the old sensor from the filter bowl or base. Catch residual fuel. Inspect the filter and seal surfaces; replace the filter if contaminated.
4
Install the new sensor with a clean sealing surface. Reconnect the harness, restore power, and check for fuel leaks and a clear water-in-fuel warning after startup.
Warning: Gasoline is flammable. Work outdoors or in a well-ventilated area away from sparks and open flame. If the later 8M0214989 form factor differs from your original lead length, confirm harness reach before final routing.
Troubleshooting & FAQ
Will this clear a water-in-fuel warning?
Only if the sensor itself failed. Drain water from the filter and replace a saturated element first; a good sensor will still warn when water is present.
Is 8M0157779 the same part?
No. Mercury lists 8M0157779 as a separate WIF sensor for a newer filter family. This listing targets the 8M0021043 / 889330 / 8M0214989 chain.
Does every Mercury 75–400 HP use this sensor?
No. Use the serial ranges in Compatible Engine Models and the OEM number on your filter or parts list.
Why Choose JLM MARINE?
- Precision Fit: Fuel and water sensor matched to Mercury 8M0021043 / 889330 applications listed above.
- Quality Control: Each batch is inspected for dimensional consistency and workmanship.
- Direct from Manufacturer: New-production aftermarket marine sensors engineered for water-separating filter WIF detection.
We can ship to virtually any address in the world with free shipping available for most regions.
For our typical US and Canadian customers , our shipping timeframes are as follows:
- Amazon FBA: orders will be delivered within 1-5 business days after placing the order (during certain special periods such as major promotions, Christmas, etc., the delivery time of Amazon FBA may be affected).
- US warehouse shipment: orders will be delivered within 5 days after placing the order.
- China warehouse shipment: orders will be delivered about 12 days after placing the order.
When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.
Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.
Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.
As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.
We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.
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