Tohatsu 4-Stroke 20HP Outboard Marine Engine Parts

(17 products)

This page focuses on Tohatsu 4-Stroke 20HP outboard engines. Use it to find compatible parts and service information, including maintenance tips, commonly replaced items, and troubleshooting guidance. You can also browse the main Tohatsu collection. Scroll to the bottom of this page to start browsing parts for this engine, and on the collection page use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category.

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How to Identify Your 20HP Model

Locate the nameplate/serial label on the transom bracket or swivel bracket; it lists the model code and serial number.
Model codes often resemble MFS20 with suffixes that indicate shaft length (S/L/XL), starting/charging options (e.g., E for electric start), and control type (tiller vs. remote).
For 4‑stroke models, you’ll see an engine oil dipstick and filler cap. Later 20HP units may use EFI, while earlier versions may be carbureted.
Record the full model code and serial number to confirm parts compatibility before ordering.

Engine/Platform Overview

EFI 4‑Stroke Platform (e.g., MFS20E)

Feature	Description
Configuration	Inline twin-cylinder, EFI 4‑stroke; compact, portable class.
Common Models	MFS20E variants (short/long shaft; tiller or remote; manual or electric start).
Advantages	Improved cold starts, smoother idle, and efficient fuel economy.
Notes	Many routine service parts (water pump items, anodes, spark plugs) are shared with the 9.9/15HP siblings; verify by model and serial.

Carbureted 4‑Stroke Platform (earlier MFS20 variants)

Feature	Description
Configuration	Inline twin-cylinder, carbureted 4‑stroke; portable outboard class.
Common Models	Earlier MFS20 carbureted versions (S/L shaft, tiller/remote, manual/electric start).
Advantages	Simple fuel system and straightforward field service.
Notes	Some components interchange with 9.9/15HP platforms; match by full model code and serial for accuracy.

Routine Maintenance & Service Parts

Intervals below are general guidelines for recreational use; always follow your official Tohatsu service manual and adjust for duty cycle and environment.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	First 20 hrs, then every 100 hrs or annually	Use marine 4‑stroke oil meeting OEM specs; replace filter at each oil change.	Oil Filters
Gear oil (lower unit)	Every 100 hrs or annually	Inspect magnet/drain plug for metal; replace seals if water intrusion is found.	Tohatsu Outboard Parts
Spark plugs	Inspect every 100 hrs; replace as needed (seasonally in harsh use)	Check gap and color; replace if fouled, worn, or out of spec.	Spark Plugs
Fuel filter / inline filter	Inspect every 100 hrs or annually	Replace sooner if debris/water is present or fuel flow is restricted.	Fuel Filters
Water pump impeller/kit	Inspect annually; replace every 2 seasons or ~200 hrs	Critical for cooling; replace more often in sandy/silty water.	Tohatsu Water Pump Repair Kits
Anodes (internal/external)	Inspect every 50–100 hrs; replace when 50% consumed	Match alloy to water type (salt, brackish, or fresh).	Anodes
Thermostat	Inspect annually	Replace if stuck or if overheat/under‑temp conditions occur.	Tohatsu Outboard Parts

*Intervals shown are typical for recreational use. Follow the stricter interval between hours and calendar time.

Frequently Used Parts Categories

Routine Service – Service & Maintenance Kits
Cooling System – Tohatsu Water Pump Repair Kits
Fuel System – Fuel Filters
Ignition / Electrical – Electrical Items and Spark Plugs
Corrosion Protection – Anodes
Gearcase Service – Tohatsu Lower Unit Seal Kits
Propulsion – Propellers

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale stream or overheat alarm	Inspect intake screens for blockage; verify impeller condition and thermostat operation.	Water pump kit/impeller, pump plate/gaskets, thermostat, intake screen, anodes.
Poor acceleration or power loss	Check fuel quality and primer bulb; inspect fuel filter and spark plugs; confirm prop condition/pitch.	Fuel filter, spark plugs, fuel pump, carburetor/injector service parts, propeller.
Hard starting or rough idle (hot or cold)	Confirm choke/EFI enrichment operation; look for air leaks in fuel line; verify plug gap.	Spark plugs, fuel filter, fuel line/primer bulb, carb kit or EFI components (as applicable).
Gearcase noise or metal in gear oil	Drain and inspect gear oil; check for water intrusion; verify prop shaft for fishing line damage.	Lower unit seal kit, bearings, thrust washer, propeller hardware, drain/vent plug seals.

FAQs

Are parts interchangeable between different years or platforms?

Many maintenance items on 20HP Tohatsu outboards overlap with 9.9/15HP models, but changes across generations (carb vs. EFI, shaft length, start/charge options) affect compatibility. Always confirm with the full model code and serial.

When should I replace the water pump impeller?

Inspect annually and replace roughly every two seasons or about 200 hours. In sandy or silty water, replace more frequently.

How often should I change lower unit gear oil?

As a baseline, change every 100 hours or annually, and any time the oil appears milky or contaminated.

What information helps confirm part compatibility?

Provide the model code (e.g., MFS20 with suffix letters), full serial number, shaft length, control type, and whether the engine is EFI or carbureted. Photos of the nameplate and the part needing replacement are also useful.

Ready to find parts for your specific 20HP model? Browse the main Tohatsu collection and use Filter & Sort to narrow by horsepower, year, and model.

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If you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.