Tohatsu 50HP 4-Stroke Outboard Marine Engine Parts

(19 products)

This page is built for Tohatsu 4‑Stroke 50HP outboard engines. Use it to quickly find compatible parts and practical service information, including maintenance intervals, common replacement items, and troubleshooting guidance. You can also browse the full Tohatsu collection anytime. Scroll to the bottom to start browsing parts for this engine, and remember that on the collection page you can use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

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How to Identify Your 50HP Model

Find the nameplate/serial label on the transom (mounting) bracket or swivel bracket. It lists the model code and serial number.
Read the model code: for 4‑stroke 50HP units this often starts with “MFS50…”. Suffix letters/numbers can indicate shaft length (S/L/UL), control type (remote vs tiller), and minor revisions.
Confirm it’s a 4‑stroke platform: you should see an engine oil dipstick and oil filter, and there is no separate 2‑stroke oil tank.
Note rigging details that affect parts: remote control vs tiller, power trim & tilt, and 15/20/25‑inch shaft length.

Engine Platform Overview

Tohatsu MFS50 Series (Inline‑3 EFI 4‑Stroke)

Feature	Description
Configuration	Inline‑3, SOHC, electronic fuel injection (EFI) 4‑Stroke outboard
Common Models	Examples include MFS50A/MFS50A2/MFS50B (naming varies by market and year).
Advantages	Quiet, fuel‑efficient running with good mid‑range torque and light overall weight for the class.
Notes	Many routine service parts overlap with 40–60HP models in the same generation. Always confirm by model code and serial number.

Routine Maintenance & Service Parts

Intervals below are general guidelines for 4‑stroke outboards. Always follow your official service manual for procedures and exact schedules.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	First 20 hrs, then every 100 hrs or annually	Use FC‑W marine 4‑stroke oil; replace filter at each oil change.	Oil Filters
Lower unit gear oil	Every 100 hrs or annually	Inspect for water intrusion (milky oil). Replace seals if contamination is found.	Tohatsu Lower Unit Seal Kits
Spark plugs	Inspect every 100 hrs; replace as needed	Check gap and condition; replace if fouled or worn.	Spark Plugs
Fuel filter / water separator	Inspect every 50–100 hrs; replace annually	Replace sooner if contaminated fuel or storage is suspected.	Fuel Filters
Water pump impeller/kit	Every 2–3 seasons (inspect annually)	Critical for cooling. Replace more often in sandy/silty or salt environments.	Tohatsu Water Pump Repair Kits
Anodes (sacrificial)	Inspect every 50–100 hrs; replace when 50–70% consumed	Use the correct alloy (zinc/aluminum/magnesium) for your water type.	Anodes
Propeller inspection	Check every outing; remove annually	Look for dings, bent blades, fishing line at seals; verify nut and cotter pin.	Propellers

*Intervals are typical for many 4‑stroke outboards; consult your specific service manual for exact guidance.

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak telltale stream or overheat alarm	Debris on intake screens, low water level, aged impeller, stuck thermostat	Water pump kit/impeller, thermostat, intake screen
Poor acceleration or power loss	Damaged or wrong‑pitch prop, clogged fuel filter, stale fuel, fouled spark plugs	Propeller, fuel filter/water separator, spark plugs
Hard starting or rough idle	Battery state, primer/fuel supply, plug condition, vacuum leaks	Spark plugs, fuel filter, fuel connectors/lines
Gearcase noise or metal in gear oil	Oil level/condition, fishing line on prop shaft, leaking seals, impact damage	Gear oil, prop shaft seals, lower unit seal kit, propeller hardware

FAQs

Are parts interchangeable across different years or platforms?

Some routine items (impellers, plugs, anodes) may interchange across 40–60HP engines within the same generation. However, revisions between model codes (e.g., MFS50A vs MFS50B) can change filters, gaskets, or electrical parts. Always confirm by model code and serial number.

When should I replace the water pump impeller?

Inspect yearly and replace every 2–3 seasons (or sooner in sandy/silty or high‑temperature operation). If you notice a weak telltale stream or overheat alerts, service the pump immediately.

How often should I change lower unit gear oil?

Typically every 100 hours or at least once per season. If the drained oil looks milky (water intrusion) or contains metal, address the cause and replace seals before running again.

What information helps confirm part compatibility?

Provide the full model code (e.g., MFS50…), serial number, shaft length (S/L/UL), control type (remote/tiller), and any photos of the nameplate and the part you are replacing.

Ready to find parts? Browse the main Tohatsu collection by horsepower, year, and model to locate compatible components for your 50HP 4‑stroke.

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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.