Name: Genuine Tohatsu Fuel Tank Cap Assy 3GT-70321-0 | 4Boats
Brand: Tohatsu-AtB
SKU: 3GT-70321-0
Price: 45.11 GBP
Availability: InStock

Black pressure washer nozzle cap with a chain on a white background

Black cap with chain on a beige background

Black metal lamp holder with chain on a white background

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£45.11

Tax included.

Fuel Tank Cap Assembly

For Tohatsu, Mercury & Nissan 2.5HP - 3.5HP Outboards

Keep your outboard's fuel system protected and functioning correctly with this premium quality Fuel Tank Cap Assembly. This part is specifically designed for the internal (integral) fuel tanks found on popular small-displacement portable engines. It provides an airtight seal when closed and features a manual breather vent to ensure consistent fuel flow during operation.

RELIABILITY: Built to meet or exceed OEM specifications using UV-stabilized, high-density plastic for long-lasting performance in marine environments.

Key Features

✔ Manual Breather: Integrated vent screw prevents vacuum lock.
✔ Complete Assembly: Includes internal rubber sealing gasket.
✔ UV Resistant: Marine-grade construction resists sun damage and cracking.
✔ Precision Fit: Direct replacement for original factory caps.

Technical Specs

Material	High-Density ABS / Nylon
Vent Type	Manual Screw-Type
Seal Material	Nitrile Rubber (Fuel Resistant)
Application	Internal/Integral Fuel Tanks

Compatibility / Fitment Guide

Make/System	Model/Application	Notes
Tohatsu / Nissan	2.5HP, 3.5HP (2-Stroke & 4-Stroke)	M2.5, M3.5, NS2.5, NS3.5 series
Mercury / Mariner	2HP, 2.5HP, 3.3HP (2-Stroke)	Japanese-built models
Mercury / Mariner	2.5HP, 3.5HP (4-Stroke)	Fits internal tanks only

OEM Cross Reference

Manufacturer	Part Number
Tohatsu / Nissan	3GP-70020-0, 309-70020-1, 309-70020-2, 309700201
Mercury / Mariner	8M0058371, 1258-8M0058371, 802141, 1258-9162

Questions & Answers

Is this a genuine original part?

This is a premium quality aftermarket replacement part from 4boats.co.uk, manufactured to meet or exceed original equipment (OE) standards for fitment and performance.

How do I know if it is compatible?

We recommend checking the SKU/MPN and Cross Reference list provided above. This cap is specific to internal tanks; if your fuel tank is part of the engine itself, this is likely the correct part.

Do I need to leave the vent screw open while the engine is running?

Yes. You must partially unscrew the central vent knob during operation to allow air into the tank. This prevents a vacuum from forming, which would stop fuel flow and cause the engine to stall.

Note: Please verify your original part design against the references at 4boats.co.uk before purchasing.

For the products under £150 the shipping is £6.99.

Free delivery for most items over £150.

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Every order is checked by the 4Boats team. Contact us before ordering if you need help with part numbers, compatibility or availability.

Genuine Tohatsu Fuel Tank Cap Assy 3GT-70321-0 | 4Boats