Fuel Pump Diaphragm Kit – Fits Mercury Marine Outboards (Replaces 89031A2, 66599A2)

$10.90 $17.00

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Fuel Pump Diaphragm Kit – Fits Mercury Marine Outboards (Replaces 89031A2, 66599A2) is backordered and will ship as soon as it is back in stock.

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Product Details

This Fuel Pump Diaphragm Kit – Fits Mercury Marine Outboards (Replaces 89031A2, 66599A2) is a crucial component for maintaining the fuel system on various Mercury Marine outboards, with a primary focus on early V6 models from the 1970s and 1980s. It is designed to restore proper fuel pump function for models including the V-135, V-150, V-175, and V-200.

This kit serves as a direct aftermarket replacement for Mercury Marine parts 89031A2 and 66599A2, as well as Sierra 18-7812, GLM 40360, and Mallory 9-37751.

Installs directly into the existing fuel pump housing.
Engineered to meet or exceed original equipment manufacturer (OEM) specifications.
Covered by a Limited Lifetime Warranty from Sierra.

Part Number Matrix

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

Brand	Part Number
Sierra	18-7812
GLM	40360
Mallory	9-37751
Mercury Marine	89031A2
Mercury Marine	66599A2

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury Marine owners, please verify your engine's serial number falls within the ranges specified in the notes to ensure an accurate fit.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury Marine	V-135	135	2-Stroke	1986–1988	89031A2	For models with serial numbers 0A904646 THRU 0C100860
Mercury Marine	V-150	150	2-Stroke	1978–1985	89031A2	Includes V-150 WORK, V-150-XR-2, V-1500, V-150 Magnum, V-150 Marathon. For models with serial numbers 4868998 THRU 0A904645, 5600162 THRU 0A904645, 0A904646 THRU 0C100860
Mercury Marine	V-175	175	2-Stroke	1976–1988	89031A2	For models with serial numbers 4301235 THRU 0C100860, 8058870 & Up
Mercury Marine	V-200	200	2-Stroke	1979–1988	89031A2	For models with serial numbers 5624878 THRU 0C100860
Mercury Marine	300	300	2-Stroke	1980–1984	89031A2	3.4 LITRE models with serial numbers 5611648 & Up

Technical Specs

Product Type: Fuel Pump Diaphragm Kit
Installation: Fuel Pump
Fuel Type: Gasoline
Dimensions: 6.0 in (Height) x 7.5 in (Width) x 1.5 in (Length)
Weight: 0.018 kg (0.04 lbs)
Warranty: Limited Lifetime (Sierra)
Other Technical Attributes: Designed to meet OEM specifications

What’s in the Box

1 x Diaphragm Assembly (89031A2)

Installation Notes

Safety first: Disconnect the battery and work in a well-ventilated area. Relieve any pressure in the fuel system.
Place absorbent rags beneath the fuel pump to catch any gasoline spillage.
Carefully note the position of the fuel inlet and outlet lines before disconnecting them from the pump.
Remove the mounting bolts that secure the fuel pump to the engine block.
Take the pump to a workbench and carefully disassemble its housing to access the old diaphragm. Pay attention to the order and orientation of screws, springs, and covers.
Remove the old diaphragm, check valve, and any associated gaskets.
Thoroughly clean the mating surfaces of the pump housing, ensuring they are free of old gasket material and debris.
Install the new diaphragm from the kit, ensuring it is seated correctly. Assemble any other included components.
Reassemble the pump housing, tightening screws in a crisscross pattern to ensure an even seal.
Mount the reassembled fuel pump back onto the engine and tighten the mounting bolts to the manufacturer's recommended torque.
Reconnect the fuel lines securely, then reconnect the battery.
Prime the fuel system (using the primer bulb) and inspect for any leaks before attempting to start the engine.

Troubleshooting & FAQ

Which Mercury V6 models does this kit fit?

It is designed for early Mercury V6 outboards, including V-135 (1986–1988), V-150 (1978–1985), V-175 (1976–1988), and V-200 (1979–1988), among others. It is critical to check your engine's serial number against the ranges listed in the compatibility table to guarantee a correct fit.

Is this a complete fuel pump or just the diaphragm?

This is a diaphragm kit designed to rebuild your existing fuel pump. It includes the primary diaphragm assembly (equivalent to Mercury part 89031A2) and is not a complete, new fuel pump.

What are the signs of a failed fuel pump diaphragm?

Common symptoms include the engine bogging down, poor acceleration, hesitation, or fuel starvation at high RPMs. You might also notice visible fuel leaking from the fuel pump's weep hole, which is a definitive sign of diaphragm failure.

How often should the fuel pump diaphragm be replaced?

There is no fixed replacement interval, but it is wise to inspect the diaphragm during routine service, especially on older engines exposed to modern ethanol-blended fuels. It should be replaced preventatively or as soon as any symptoms of failure appear to avoid being stranded on the water.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost?

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

Warranty & returns?

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 (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs 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 QC.

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