Mercury Carburetor Fuel Pump Diaphragm 16275
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Mercury Carburetor Fuel Pump Diaphragm 16275
Part Number: 16275
Brand: Mercury / Quicksilver
Product Type: Carburetor Fuel Pump Diaphragm (OEM)
System: Outboard Fuel System / Carburetor
Position: Outer fuel pump diaphragm — beneath pump cover 16272, adjacent to pump cover gasket 16274
Quantity Required: 1 per carburetor
GTIN / UPC: 745061117594
Approximate Weight: 5 g
What This Part Does
The 16275 is a genuine OEM fuel pump diaphragm that forms part of the integrated fuel pump section in the carburetor on selected small Mercury and Mariner 2-stroke outboards. It sits directly beneath pump cover 16272 alongside pump cover gasket 16274 and works with the second diaphragm 16325 deeper in the same assembly to draw fuel from the tank and deliver it to the carburetor float bowl. A cracked, hardened, or torn diaphragm causes weak or inconsistent fuel delivery.
Note: 16275 is the outer (upper) diaphragm. A separate second diaphragm, 16325, occupies a different position in the same fuel pump section — they are not interchangeable and both should be inspected whenever the pump cover is removed.
Compatible Applications
Confirm your engine horsepower, serial number, and carburetor diagram before ordering. Mercury used several carburetor versions across these horsepower ranges.
- Mercury / Mariner 4 HP 2-stroke
- Mercury / Mariner 5 HP 2-stroke (multiple serial ranges)
- Mercury / Mariner 6 HP 2-cylinder 2-stroke
- Mercury / Mariner 8 HP 2-cylinder 2-stroke
- Mercury / Mariner 8 HP SeaPro 2-stroke
- Mercury / Mariner 9.8 HP 2-stroke
- Mercury / Mariner 9.8 HP SeaPro 2-stroke
- Mercury / Mariner 9.9 HP 2-cylinder 2-stroke
Serial Number Notice
Do not order by position description alone — confirm against the Mercury carburetor diagram for your engine serial number. Within the same fuel pump section, do not confuse:
- 16275 — Outer fuel pump diaphragm (this part)
- 16325 — Second (inner) pump diaphragm — different position, not interchangeable
- 16274 — Pump cover gasket
- 16326 — Pump body gasket
When to Replace
- Fuel delivery is weak or inconsistent and pump section is being diagnosed
- Diaphragm is hardened, torn, warped, or shows fuel damage on inspection
- Diaphragm has lost flexibility when tested by feel
- Carburetor fuel pump rebuild is being performed
- Pump cover is removed and existing diaphragm shows any deterioration
Installation Notes
- Install 16275 in the exact orientation shown in the Mercury carburetor diagram for your engine model
- While the assembly is open, inspect the adjacent pump cover gasket 16274, second diaphragm 16325, pump body gasket 16326, pump body 16268, and check valve 16269
- Do not reuse the old diaphragm after removal — a diaphragm that appeared intact on the bench often fails under fuel pressure and heat cycles
- Check for fuel delivery and signs of leaks after reassembly and before returning the engine to service
Part Number Cross-Reference
- OEM Part Number: 16275
- Associated carburetor repair kit: 855546A1 (includes 16275 as a component — useful reference for a full carburetor overhaul)
Parts Desk Insights
Best use case: Order 16275 when rebuilding the carburetor fuel pump section on a 4–9.9 HP Mercury or Mariner 2-stroke — replacing both diaphragms (16275 and 16325) and the pump cover gasket (16274) at the same time is the right approach since access is already there and the parts are low cost relative to a repeat fuel delivery issue.
Common issues: The most frequent mistake is ordering only one diaphragm when two are used in the same pump section — 16275 is the outer diaphragm and 16325 is the inner diaphragm. Both should be replaced during any pump rebuild. A second common issue is skipping diaphragm replacement during carburetor cleaning — a diaphragm that looks fine when cold often shows cracks or loss of flexibility once it’s been back under fuel and heat, causing the same fuel delivery symptoms to return.
Related Parts
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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