Tohatsu 4-Stroke 8-20HP Outboard Parts

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This page supports Tohatsu 4-Stroke 8–20HP outboard engines. Use it to find compatible parts and service information, including maintenance tips, common replacement items, and troubleshooting guidance. You can also browse the main Tohatsu collection. Scroll to the bottom of the 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 8–20HP Model

Locate the nameplate/serial label on the transom bracket (usually port side) or on the swivel bracket. Record the model code and serial number.
Model codes typically begin with MFS followed by horsepower (e.g., MFS8, MFS9.8, MFS9.9, MFS15, MFS20). Suffix letters indicate shaft length (S=short, L=long), electric start (E), tiller vs. remote, and other options.
Platform cues: 8/9.8HP models are commonly carbureted twin-cylinder; 9.9/15/20HP models are often the newer EFI twin-cylinder platform. Look for an EFI fuel rail and sensors versus a carburetor and choke/primer.
Use the exact model and serial to confirm parts such as water pump kits, gearcase seals, and ignition components.

Platform Overview

Portable Twin 8–9.8HP (Carbureted)

Feature	Description
Configuration	4‑stroke, inline‑2, carbureted; manual or electric start; tiller or remote options.
Common Models	Examples include MFS8 and MFS9.8 variants (short/long shaft, manual/electric).
Advantages	Lightweight, simple fuel system, easy dockside service, excellent portability.
Notes	Verify impeller and gearcase seal kit by model code and shaft length. Prop pitch varies by load and hull.

Portable Twin 9.9–20HP (EFI)

Feature	Description
Configuration	4‑stroke, inline‑2, EFI; manual or electric start; tiller/remote, power trim on select variants.
Common Models	Examples include MFS9.9, MFS15, MFS20 EFI variants (S/L shafts, manual/electric, tiller/remote).
Advantages	Clean starting, strong mid‑range torque, better fuel economy and altitude compensation vs. carbureted units.
Notes	Use the model code to match EFI‑specific fuel filters and gaskets. Many props and anodes overlap across 9.9–20HP.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use; always follow the official service manual for your specific model and operating conditions.

Item	Interval*	Remarks	Parts Link
Engine oil + filter	First 20 hrs, then every 100 hrs or annually	Use marine 4‑stroke oil per spec; replace filter with each oil change.	Oil Filters
Gear oil (lower unit)	Every 100 hrs or annually	Inspect for water intrusion (milky oil) and metal fines. Replace seals if leakage is found.	Tohatsu Lower Unit Seal Kits
Spark plugs	Inspect every 100 hrs; replace 200–300 hrs or as needed	Set correct gap; replace if fouled, worn, or corroded.	Spark Plugs
Fuel filter / water separator	Every 100 hrs or annually	Replace more often with ethanol fuel or dirty tanks; keep spare onboard.	Fuel Filters
Water pump impeller / kit	Every 2–3 seasons (or 200 hrs)	Replace sooner if weak telltale, overheating, or after sand/silt use.	Tohatsu Water Pump Repair Kits
Anodes (sacrificial)	Inspect every 50 hrs; replace when 50% consumed	Choose material for your water (aluminum for brackish/salt, magnesium for fresh, zinc for traditional salt).	Anodes
Propeller inspection	Check every outing	Remove debris; inspect hub for damage and pitch suitability.	Propellers

Frequently Used Parts Categories

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

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak telltale or overheat alarm	Inspect intake screens for debris; verify strong telltale; review service history of impeller.	Water pump repair kit, thermostat, intake screen
Hard starting or rough idle	Use fresh fuel; prime the system; check inline filter; inspect/replace spark plugs and plug caps.	Fuel filter, spark plugs, primer bulb, EFI filters (where equipped)
Poor acceleration / power loss	Check prop for damage or fouling; verify correct prop pitch; look for fuel restriction or misfire.	Propeller, fuel filter, spark plugs
No charging / weak battery (electric‑start models)	Measure battery voltage; inspect fuses and wiring; test rectifier/regulator output if equipped.	Rectifier/regulator, fuses, wiring connectors
Gearcase noise or metal in gear oil	Drain and inspect gear oil; look for water intrusion; check prop shaft for fishing line cutting seals.	Lower unit seal kit, bearings, shims

FAQs

Are parts interchangeable between different years or platforms?

Some items overlap across 8–9.8HP and 9.9–20HP families, but many components differ (cooling, fuel, and gearcase parts). Always confirm by model code and serial number.

When should I replace the water pump impeller?

As a rule of thumb, every 2–3 seasons (or about 200 hours). Replace immediately if the telltale weakens, the engine overheats, or after running in sandy or silty water.

How often should the lower unit gear oil be changed?

Every 100 hours or annually, and any time you see milky oil, metal shavings, or after an impact or submersion event.

What information do you need to confirm part compatibility?

Provide the full model code, serial number, shaft length (S/L/XL), start/control type (manual/electric, tiller/remote), and a brief description or photo of 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 8–20HP four‑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.