Mercury MerCruiser Quicksilver Carburetor Fuel Pump Diaphragm 16325
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Mercury MerCruiser Quicksilver Carburetor Fuel Pump Diaphragm 16325
Part Number: 16325
Brand: Mercury / Quicksilver
Product Type: Carburetor Fuel Pump Diaphragm (OEM)
System: Outboard Fuel System / Carburetor
Position: Second (inner) diaphragm in the fuel pump section — deeper in the assembly than the outer diaphragm 16275
Quantity Required: 1 per carburetor
GTIN: 745061117686
Approximate Weight: 5 g
What This Part Does
The 16325 is a genuine OEM fuel pump diaphragm used in the carburetor fuel pump section on selected small Mercury and Mariner 2-stroke outboards. It sits deeper in the pump assembly than the outer diaphragm 16275, and both diaphragms work together to draw fuel from the tank and deliver it to the carburetor float bowl. A cracked, hardened, or torn inner diaphragm causes weak or inconsistent fuel delivery and can be difficult to diagnose without fully disassembling the pump section.
Note: 16325 is the inner (second) diaphragm. A separate outer diaphragm, 16275, occupies a different position closer to the pump cover. Both should be inspected and replaced whenever the pump section is disassembled.
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:
- 16325 — Inner (second) pump diaphragm (this part)
- 16275 — Outer (first) pump diaphragm — different position, not interchangeable
- 16274 — Pump cover gasket
- 16326 — Pump body gasket
Carburetor Fuel Pump Assembly Components
The carburetor fuel pump section commonly includes the following components:
- 16268 — Pump body
- 16269 — Check valve (qty 2)
- 16270 — Check-valve screw
- 16271 — Check-valve nut
- 16325 — Diaphragm, inner (this part)
- 16275 — Diaphragm, outer
- 16274 — Pump cover gasket
- 16326 — Pump body gasket
Keep the diaphragm stack in the exact order shown in the engine-specific Mercury carburetor diagram for your engine model.
When to Replace
- Fuel delivery is weak or inconsistent and the 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 the inner diaphragm shows any deterioration
Installation Notes
- Install 16325 in the exact orientation shown in the Mercury carburetor diagram for your engine model
- While the assembly is open, replace the outer diaphragm 16275, pump cover gasket 16274, and pump body gasket 16326 at the same time
- Inspect check valves 16269 during the overhaul and replace if worn or sticking
- 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 before returning the engine to service
Part Number Cross-Reference
- OEM Part Number: 16325
- GTIN: 745061117686
- Associated carburetor repair kit: 855546A1 (includes 16325 as a component — useful reference for a full carburetor overhaul)
Parts Desk Insights
Best use case: Order 16325 together with outer diaphragm 16275 and pump cover gasket 16274 when rebuilding the carburetor fuel pump section on a 4–9.9 HP Mercury or Mariner 2-stroke. Replacing both diaphragms at the same time is the right approach — access is already there and the parts are low cost relative to a repeat fuel delivery problem.
Common issues: The inner diaphragm (16325) is the one most often overlooked during carburetor service — technicians sometimes replace only the outer diaphragm (16275) because it is more visible, and the engine returns with the same fuel delivery issue because the inner diaphragm was left in place. Always replace both when the pump section is open. Also confirm the diagram position — 16325 and 16275 sit in adjacent positions and look similar but are not interchangeable.
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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