Mercury Quicksilver Fuel Pump Gasket 27-34213 | MerCruiser Mechanical Fuel Pump Block Gasket

Mechanical Fuel Pump Mounting Gasket for MerCruiser Engines

The Mercury Quicksilver 27-34213 is an OEM fuel pump mounting gasket that seals the mechanical fuel pump flange to the engine block on compatible MerCruiser gasoline engines. It prevents crankcase oil from seeping out at the pump mounting face — a common source of oil weeping on older MerCruiser engines that is often mistaken for a more serious leak.

This gasket should be replaced any time the mechanical fuel pump is removed. Reusing a compressed or heat-cycled gasket is a frequent cause of repeat oil seepage at the pump flange.

Part Information

• Part Number: 27-34213
• Short Reference: 34213
• Brand: Mercury / Quicksilver
• Official Product Type: Mechanical Fuel Pump Mounting Gasket
• Barcode / UPC: 745061137059
• Aftermarket Cross-References: Sierra Marine 18-0889, GLM Marine 31360, Mallory Marine 9-34213, Pleasurecraft 3705042, Volvo Penta 3852095
• Approximate Dimensions: 3.00" L × 3.00" W × 0.25" H
• Approximate Weight: 0.02 kg

Compatible Applications

• MerCruiser 2.5L / 110 hp engines with mechanical fuel pumps
• MerCruiser 3.0L / 120 hp and 140 hp engines with mechanical fuel pumps
• MerCruiser inline-6 150 hp and 160 hp engines with mechanical fuel pumps
• Select classic MerCruiser GM-based V6 and V8 gasoline engines with mechanical fuel pump configurations
• Any MerCruiser engine where the parts diagram specifies 27-34213 or 34213 at the fuel pump mounting location

Fitment Note: Verify by engine serial number, fuel pump style, and the Mercury parts diagram before ordering. Mechanical fuel pump gasket fitment can vary by engine block, pump base design, and production range. This gasket applies to mechanical (camshaft-driven) fuel pump applications only — not electric fuel pump systems.

System & Diagram Position

This gasket is part of the fuel delivery system. In the Mercury parts diagram it appears in the fuel pump section, at the interface between the mechanical fuel pump body and the engine block mounting pad. It is the sealing layer between the pump flange and the block face, positioned directly behind the pump body where the pump arm contacts the camshaft eccentric.

Dimensions

• Approximate Length: 3.00"
• Approximate Width: 3.00"
• Approximate Thickness: 0.25"

When to Replace

• Any time the mechanical fuel pump is removed from the engine block
• Oil seepage or weeping at the fuel pump mounting flange
• Gasket is visibly compressed, torn, hardened, or cracked
• During an engine rebuild or major fuel system service
• Preventive replacement whenever the pump is off for any reason

Service Interval

This gasket does not have a standalone replacement interval. It should be replaced any time the fuel pump is removed — treating it as a single-use gasket is the correct approach. Inspect the pump mounting area for oil seepage during routine engine service.

Installation Notes

• Clean both the engine block mounting pad and the fuel pump flange thoroughly before installing the new gasket — any residue from the old gasket will prevent a proper seal
• Do not use gasket sealant on this gasket unless specifically directed by the Mercury service manual for your engine
• Inspect the fuel pump arm and camshaft eccentric for wear before reinstalling the pump
• Torque the pump mounting bolts to the specification in the Mercury service manual for your engine
• After reassembly, run the engine and inspect the pump flange area for oil seepage before returning to service

Related Parts

• Mercury Sea Water Pump Gasket 27-881603001
• Mercury MerCruiser Water Pump to Gear Housing Gasket 27-85610
• Mercury Quicksilver Exhaust Manifold Gasket 27-33395
• Mercury Quicksilver Fuel Line Connector 22-33821
• Mercury Oil Filter Adaptor O-Ring 25-33756

Technical FAQ

Q: Can I reuse this gasket after removing the fuel pump?
A: No. Once compressed and heat-cycled, the gasket will not seal reliably when reinstalled. Always use a new gasket when reinstalling the fuel pump.

Q: Will this gasket fit my electric fuel pump?
A: No. This is a mounting gasket for mechanical (camshaft-driven) fuel pumps only. Electric fuel pump systems use different mounting configurations and do not use this gasket.

Q: What causes oil seepage at the fuel pump flange?
A: The most common causes are a compressed or failed pump gasket, a warped pump flange, or loose mounting bolts. Replacing the gasket and torquing the bolts correctly resolves most cases. If seepage continues after a new gasket, inspect the pump flange for flatness and the block mounting pad for damage.

Q: Does this gasket also seal fuel, or just oil?
A: This gasket primarily seals the crankcase at the fuel pump mounting pad — it prevents oil from seeping out at the block face. The fuel passages are sealed internally within the pump body itself. If fuel is leaking externally from the pump, the pump diaphragm or body is the more likely source.

Parts Desk Insights

Best use case: This gasket is the right part for any mechanical fuel pump removal on a compatible MerCruiser engine — whether you are replacing a failed pump, diagnosing an oil seep at the pump flange, or doing a full engine service. At this price, it should always be replaced rather than reused whenever the pump comes off.

Common issues: The most common issue is oil seepage at the pump flange after reinstalling the pump with the old gasket. A gasket that looks intact after removal will not seal the same way once it has been compressed and disturbed. A second common issue is misidentifying the source of the leak — oil seeping from the pump gasket can run down the block and appear to come from a lower location. If you see oil near the pump area, check the mounting flange first before assuming a more serious leak.