Fuel Pump Diaphragm Kit – Fits Mercury/Mariner/Force 30-275 HP 2-Stroke (Replaces 42909A4/857005A1)

$23.99 $38.00

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Fuel Pump Diaphragm Kit is engineered for a wide range of Mercury, Mariner, and Force 2-stroke outboard engines, covering models from 30 HP to 275 HP. It provides a reliable, vehicle-specific fit to restore fuel system performance and efficiency.

It serves as a direct interchange for multiple OEM and aftermarket part numbers, including Mercury 42909A4 / 857005A1, Sierra 18-7818-1, and GLM 40280, ensuring broad compatibility.

Installation: Vehicle Specific Fit
Operation: Mechanical pump components
Material: Durable rubber diaphragm designed for gasoline applications

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket brands.

Brand	Part Number
Mercury	857005A1
Mercury	42909A4
Mercury	42909A3
Mercury	42909A2
Mercury	42909A1
Quicksilver	857005A1
Sierra	18-7818-1
GLM	40280

Engine & Model Compatibility

Confirm your engine model and part number in the table below.

For Mercury engines, this kit fits various 2-stroke outboards from 30 HP to 275 HP.

Compatible Mariner models include a range of 2-stroke outboards from 75 HP to 115 HP.

This diaphragm kit is also suitable for many Force 40–120 HP 2-stroke outboards.

Brand	Model	Rated HP	Stroke	OEM Part No.	Notes
Mercury	Outboard	75	2-Stroke	10753278D
Mercury	Outboard	90	2-Stroke	10903118F, 10903218F, 10904128D, 10904728D
Mercury	Outboard	100	2-Stroke	11004218D
Mercury	Outboard	115	2-Stroke	11154728D
Mercury	Outboard	125	2-Stroke	11254128D, 11254228D
Mercury	100 ELPTO	100	2-Stroke	1100412BC, 1100412GD
Mercury	115 ELPTO	115	2-Stroke	1115452BD, 1115412GD
Mercury	Various 30-65 HP	30-65	2-Stroke	857005A1	Per Quicksilver documentation
Mariner	Outboard	75	2-Stroke	71004128D, 71004218D
Mariner	Outboard	90	2-Stroke	70903118F, 70904128D, 70904728D
Mariner	Outboard	100	2-Stroke	71004128D, 71004218D
Mariner	Outboard	115	2-Stroke	71154728D
Mariner	100 ELPTO	100	2-Stroke	7100412GD
Mariner	100 EXLHPTO	100	2-Stroke	7100421GD
Mariner	115 JET 80	115	2-Stroke	7115472CD, 7115472DD, 7115472ED, 7115472FD
Force	Outboard	40-120	2-Stroke	Various	Compatible with multiple Force models per Crowley Marine data

Technical Specs

Product Type: Fuel Pump Diaphragm Kit
Installation: Vehicle Specific Fit
Fuel Type: Gasoline
Housing Material: Rubber (Diaphragm)
Dimensions: 12.5" L x 11.0" W x 1.0" H
Weight: 20 g (0.7 oz)
Warranty: 30-day return/replacement
Other Technical Attributes: Mechanical operation mode

What’s in the Box

12 x Diaphragm Kit Components (Replaces 857005A1) including:

Fuel pump diaphragms
Gaskets
Check valves
Spring
Cap
Screws

Installation Notes

Disconnect the battery and safely relieve all fuel system pressure.
Place a shop towel below the fuel pump to absorb any spills.
Carefully disconnect the fuel lines, noting their positions for reassembly.
Remove the mounting screws to detach the old fuel pump assembly.
Disassemble the pump housing, paying close attention to the order of the diaphragm, gaskets, and internal components.
Clean all housing surfaces to ensure a clean, debris-free seal.
Install the new components from the kit in the correct sequence.
Reassemble the pump housing and tighten the screws evenly to the manufacturer's recommended torque.
Mount the reassembled pump, reconnect the fuel lines, and reconnect the battery.
Prime the fuel system and carefully inspect for any leaks before starting the engine.

Troubleshooting & FAQ

How do I know if my fuel pump diaphragm is failing?

Common signs include the engine bogging down at high speeds, difficulty starting, rough idling, excessive fuel consumption, or visible fuel leaks from the pump housing.

Will this fit my specific Force engine model?

This kit is listed as compatible with many 40–120 HP Force models. We strongly recommend cross-referencing your old pump's part number with our Part Number Matrix to ensure an exact match before ordering.

What is the recommended replacement interval?

There is no fixed interval from the manufacturer, but it is good practice to inspect the diaphragm during annual service. Replace it immediately if you notice signs of stiffness, cracking, discoloration, or leakage.

Is this kit difficult to install?

Installation is straightforward for those with mechanical experience. It requires basic hand tools and careful handling of fuel system components. If you are unsure, professional installation is recommended.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Our parts are manufactured in an ISO 9002 facility and are batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

This product is covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.

Safety & Important Info

Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or quality control.

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