Outboard Motor Repair Level 2

Who it is for. People who have finished Outboard Motor Repair (Level 1), or who can show the same skills. National Proficiency II covers varied work, mostly routine, under limited supervision.

Bridge from Level 1: what you already know

Level 1 told you to stop and call a mechanic for harder faults. Level 2 is where you become that mechanic: strip a spare carburettor, replace an impeller, change gear oil, measure a battery, and write a proper quote. Some jobs stay dealer-only or need the maker's data (ignition timing, carburettor jet and float settings). The book says so clearly each time.

How the module works

Each unit has learning outcomes, performance criteria, the range and the evidence your assessor needs. You are judged Competent or Not Yet Competent. About 70% of your time is hands-on work.

Labels you will see.

• (general practice, not verified) means the method is standard workshop teaching but no maker's manual or source we could read confirmed it. Check with a licensed mechanic or the dealer.
• Trainer to check means the step is not in any free manual we could read. Your trainer must confirm it against the engine's own workshop manual before you do it for real.
• Example means an invented number for practice, not a real price.

Competency standard

Range. Two-stroke pre-mix and four-stroke outboards; carburettor first, then fuel-injection awareness. Evidence. Fuel-path sketch; carburettor job sheet; plug record; oral questions.

The fuel path, in order

Trace it with your finger on a real engine. Fuel goes: tank (with its vent screw and pickup filter) → fuel hose and connector → primer bulb → filter (cup or spin-on) → fuel pump → carburettor (or vapour separator on a fuel-injected engine) → cylinder. A fault anywhere along this path starves the engine.

The Tohatsu two-stroke manual lists these hard-start causes: empty tank, fuel line wrongly connected, air entering the fuel line, a damaged hose, a closed air vent on the tank cap, a clogged filter, pump or carburettor, wrong oil or petrol, flooding from excessive petrol, poor carburettor adjustment, dirty or non-specified plugs, weak or no spark and a missing safety-switch lock plate.

Fuel problems that look like engine problems

• Water in the fuel. The engine starts, then dies or misfires. Look for water in the see-through filter cup. Ethanol blends take up water; at about 0.5% water, it can bond with the alcohol and sink to the pickup. Additives cannot remove water or make stale fuel good again. Drain fuel from the vapour separator or carburettor drain until what comes out is clean, clean the tank and tank filter, and replace the filter.
• Stale fuel. Honda says petrol can deteriorate in as little as 15 days. Fuel left in a carburettor forms gum and varnish and sticks the float valve.
• Wrong mix. Too little oil in a two-stroke can seize the engine; too much oil fouls plugs and makes smoke. Never mix different brands of oil, because they can gel and block the filter screen.
• Four-stroke engines must not run on premix. The four-stroke manual wants plain petrol with separate crankcase oil. This is our inference from the manuals, not a Ghana rule.

Carburettor: what it does

The carburettor mixes air and petrol. Fuel enters the float bowl; a float and needle valve keep the level steady; the air flowing through draws fuel up through small jets; a choke or primer richens the mix for starting and a throttle plate controls the flow. Dirt or gum in the jets is the usual fault on stored engines.

Practical: clean a spare carburettor (bench job)

The sequence below follows a general how-to article (not retrievable in full) and standard workshop practice. Trainer to check against the workshop manual for the engine in front of you.

Common mistakes. Mixing up the jets; enlarging a jet with wire; losing the float pin; overtightening the aluminium screws; leaving fuel in the bowl on the bench; refitting an old gasket.

Ignition: reading the plug

Level 1 taught you to remove, inspect and fit a plug. Now read what it says.

Plug facts you can verify (examples, from two makers).

Replace a plug with a worn electrode or a cracked or chipped insulator; use only the specified type; measure the gap with a wire-type feeler gauge; fit by hand first to avoid cross-threading, then tighten (18 Nm on the Tohatsu 25/30, or 1/4-1/2 turn past finger-tight if you have no torque wrench, then check with a torque wrench as soon as you can).

Reading a plug (general practice, not verified; learn it from plugs from your own engines):

Spark test (general practice, not verified)

No manual we read gives a standard spark test or coil resistance values. Teach it this way, and have the trainer confirm it for each engine.

Compression

Low compression means a worn or damaged engine, and the plug or carburettor will not cure it. A compression test uses a compression gauge in the plug hole while the engine is cranked with all plugs out and the throttle open. Compression values for any engine: not verified. Teach it as a comparison: the cylinders of the same engine should be close to each other; a big difference points at a worn cylinder or ring. Record on a known-good engine and compare (general practice, not verified). A low reading ends the job: quote an engine rebuild or replacement, or send it to the dealer.

Where fuel injection fits

The Tohatsu 25/30 four-stroke has fuel injection (EFI), not a carburettor. A beginner does the checks in this book (fuel, filter, plugs, battery, water) on an EFI engine, and sends injector, sensor and computer faults to a dealer with the right tools.

Check yourself

1. Name the order of the fuel path from tank to cylinder.
2. Why do you never poke a carburettor jet with wire?
3. Hold a plug cap by what part during a spark test, and why?

Competency standard

Range. Sea-water-cooled outboards, two-stroke and four-stroke. Evidence. Cooling-path sketch; overheating checklist; impeller job sheet; oral questions.

The cooling path

Water enters through the intake holes in the gear case, goes up to the water pump (a rubber impeller spinning in a cup), through passages around the cylinders, past a thermostat, and leaves through the exhaust and a small tell-tale (check) port that squirts a stream so you can see it is working. Water also lubricates the pump, so never run the engine dry: the impeller is destroyed very fast.

What the engine and the maker's manual say

• Tohatsu 25/30 has a warning system: a continuous beep and lamp for engine over-speed, low oil pressure or water over-temperature, and the engine speed is limited. A start-up test gives one beep and the lamp for about 5 seconds.
• Most outboards reduce rpm when they overheat; watch the gauge and listen for the horn.
• Coarse particles (salt, sand, shell) wear the impeller blades or clog the thermostat.
• Rubber impellers age even if unused ("dry rot"). Tohatsu says inspect each year and replace at least yearly depending on use; the M40D2 table puts impeller replacement at every 12 months.

What to do when no water comes from the tell-tale

1. Stop the engine at once. Do not restart until fixed.
2. Clear the tell-tale hole with a thin wire or a puff of air.
3. Check the intake holes on the gear case for blockage: weed, plastic, a net or mud.
4. If the intake is clear and there is still no water, the impeller probably needs replacing, or something is blocking the lower unit.
5. If the thermostat is suspected (the engine runs hot but water flows), take the engine to the dealer, or remove and test the thermostat as taught by your trainer (general practice, not verified).

The two-stroke M40D2 lists overheating causes as too little cooling-water flow, a clogged or damaged pump, or a faulty thermostat.

Overheating checklist (use in this order)

Impeller replacement: the sequence

This is not in any free owner's manual we could read. The owner's manuals list it as a dealer job. The sequence below is our own general sequence. It is (general practice, not verified; follow the engine's workshop manual). Trainer to check it against a permitted workshop manual for your engine before you do the job for a customer.

Common mistakes. Putting the impeller in backwards; losing the key; letting the shaft turn the wrong way while lowering; forgetting a gasket; not removing broken vane pieces; running the engine dry on the bench; reusing the split pin.

Warm-up and flushing

The Tohatsu pre-season warm-up: 3 minutes in neutral, 5 minutes at slow speed, and 10 minutes at half throttle. After use in salt, brackish or dirty water, flush with fresh water. Some makers flush with the engine off through a flush port (Tohatsu, Honda), and Yamaha's page describes flushing while running; follow your own manual. Do not run the engine with the propeller fitted when flushing with a hose or in a test tank.

Check yourself

1. What do you do first when no water comes from the tell-tale?
2. Why must you never run an outboard dry, even for a few seconds?
3. Name two things you check on an old impeller.

Competency standard

Range. Outboards from small to about 40 hp; lower units and propellers. Evidence. Gear-oil job sheet; propeller job sheet; anode check; oral questions.

Gear oil: change and read

Use the oil grade and quantity from your own manual. Examples: Tohatsu 25/30 four-stroke: API GL-5, SAE 80-90, about 360 mL; Tohatsu M40D2: GL-5, SAE 80-90, 500 mL. Honda gear-case oil sheet: BF40D/50D 14.5 fl oz of GL-4 as printed on that sheet; the sheet lists GL-4 for some Hondas while Tohatsu says GL-5, so always follow your own manual.

Common mistakes. Filling from the top; reusing washers; forgetting the level bolt; wrong oil grade; overtightening a bolt in aluminium; leaving the motor tilted with no lock.

If the oil is milky, do not run the engine. Water has got past a seal. The usual causes are a worn propeller-shaft seal, fishing line or net wrapped round the shaft cutting the seal, or a worn driveshaft seal (general practice, not verified). Fix the cause, not just the oil: the lower unit needs strip-down, a new seal kit and a pressure test, so quote this as a bigger job or send it to a dealer. Water in engine oil (milky) means do not run it and consult a dealer.

Remove and refit a propeller (nut and split pin)

Choosing and checking the propeller

A propeller must let the engine reach its full-throttle rpm range under normal load. Examples from the plate: Tohatsu 25: 5,000-6,000 rpm; 30: 5,250-6,250 rpm; M40D2: 5,000-5,700 rpm. Use the range on your engine's plate or in its manual.

A tachometer (rpm meter) on a full-throttle run with the usual load tells you the answer. If the rpm is below the range, the load or propeller is too heavy ("too much bite") and the engine overworks; if above, the propeller is too light or is ventilating (sucking air) or cavitating (general practice, not verified; ask a dealer for the right size). Cavitation and ventilation can also come from a bent or damaged propeller or a transom that is too high or too low. Do not copy another canoe's propeller: its engine, weight and fishing method may be different.

Shear pin (small outboards): trainer to check

Anodes, impact and a submerged motor

• The sacrificial anode protects the engine from electrolytic corrosion. Replace it when it has eroded to less than about two-thirds of its original size (eroded more than one third). Never paint or grease an anode. Retighten the anode bolt at each inspection. Honda also says do not paint or coat anodes.
• Hit an underwater object? Stop the engine at once, check the controls, the gear case and the transom, return slowly, and have the motor checked.
• Submerged motor: do not start it. Wash with fresh water, drain water and oil, take out the plugs and drain the cylinders by pulling the starter, change the oil and filter, spray oil into the cylinders, and take it to a dealer; the oil may need changing again.

Check yourself

1. Which bolt do you remove first when draining gear oil, and how do you fill?
2. What does milky gear oil tell you?
3. When must an anode be replaced?

Competency standard

Range. 12 V systems on electric-start outboards; stop-switch and lanyard on all engines. Evidence. Multimeter record; battery check sheet; kill-switch check; oral questions.

Battery safety

• The battery holds sulphuric acid. Wear eye protection and gloves; flush skin or eyes with water if splashed.
• It gives off explosive hydrogen gas, so charge in a ventilated place with no sparks and no smoking, and keep it away from the fuel tank.
• Disconnect the negative (-) lead first. Connect the positive (+) lead first.
• Keep the battery in a secured box away from spray; the recommended battery for the Tohatsu 25/30 is 12 V 70 Ah. Use the size in your own manual.

The multimeter

A multimeter measures volts (pressure), amps (flow) and ohms (resistance). For battery work you use only DC volts (a straight line with dots on the dial, "V ⎓").

What the readings mean (general practice, not verified; the 12-13 V and 13-15 V ranges are Yamaha's):

A hydrometer reading is another check: Tohatsu's table gives about 1.280 specific gravity as fully charged and 1.120 as discharged. Charge a flat battery in a ventilated place, and recharge a stored one every month.

Starting problems

Electric-start engines will not crank for these causes: a weak or flat battery, loose or corroded terminals, a bad earth or cable, a faulty starter or solenoid, not in neutral, a blown fuse, a stop switch problem or a bad key switch.

Fuse

If a fuse blows: disconnect the negative lead first, replace it only with the same rating, and find out why it blew. A bigger fuse is a fire risk.

Kill switch, lock plate and lanyard

The emergency stop switch and lanyard stop the engine if the operator falls overboard. The lanyard must be attached to the operator. Too short a pull may cut the engine on a normal movement, so Tohatsu's lanyard is coiled at 500 mm and extends to 1,300 mm. The engine will not start without the lock plate in place, and a stop-switch short circuit, a missing lock plate, a ground fault or a wire break are all listed causes of a no-start.

Charging system

On a pull-start engine with a small charging coil, you may measure only voltage. Charging-coil resistance, regulator output and CDI values: not verified for any engine. Measure the values on a known-good engine of the same model, write them in your logbook, and use them for comparison. Never guess.

Check yourself

1. In what order do you disconnect and connect a battery?
2. What is the normal running voltage Yamaha gives?
3. What can you never do to a kill switch?

Competency standard

Range. Two-stroke and four-stroke outboards; no start, hard start, rough running, no power, overheating. Evidence. Fault-finding record for two faults; test-run record; oral questions.

The six-step routine

1. Ask. When did it stop? What was it doing? Cold or hot? What fuel? When was it last serviced? Has it hit anything or been in salt water?
2. Look and smell. Leaks, wet spots, a fuel smell, burnt smell, loose wires, a damaged propeller, corrosion.
3. Test the easy things first. Lanyard key and lock plate, gear in neutral, fuel in the tank, vent screw open, hose connected properly, primer bulb firm.
4. Test by system. Fuel, then spark, then air and compression, then water, then electrical (as taught in Units 1-4).
5. Change one thing at a time, and test after each. If you change five things you will not know which one fixed it.
6. Write down what you found and what you did. Take photos of the old part before you throw it away.

The "fuel, spark, air or compression, water" order is our teaching design, not a single manufacturer's rule (general practice, not verified). The causes in the tables come from the Tohatsu manuals.

Table 1: Will not start or hard to start

Four-stroke extras: low engine oil, clogged oil filter, low compression, not in neutral, ignition key switch, starter motor or solenoid.

Table 2: Overheating or no water from the tell-tale

Table causes in the Tohatsu manual: too little cooling-water flow, a clogged or damaged pump, a faulty thermostat.

Table 3: Rough idle, stalls, hesitates

Same fuel and spark causes as Table 1, plus: a broken recirculation pipe, a faulty thermostat, a damaged or bent propeller, a transom set too high or too low, an unbalanced load, wrong throttle-link or ignition timing.

Table 4: No power, cannot reach full rpm

Table 5: Water in the fuel or oil

A worked example of a diagnosis (example)

A canoe owner says: "It was running well, then died and will not restart." Your steps: Ask (hit nothing, premix fuel, last service 4 months ago). Look (fuel smell near the carburettor). Easy checks (key and lock plate in; tank has fuel; vent open). Fuel: the primer bulb is soft and will not firm up: air is entering the fuel line. You find a cracked connector at the engine end. Change one thing: fit a new connector. Test: the bulb firms up; the engine starts. Write down: "Air leak at connector; replaced; test-run 10 minutes OK." The cheap part and a quick check saved a long strip-down.

Safe test running

Check yourself

1. Why change only one thing at a time?
2. How deep must the water be over the anti-ventilation plate in a test tank?
3. Why must a test run never happen in a closed workshop?

Competency standard

Range. Small repair jobs for canoe owners and boat owners. Evidence. Quote; job card; price survey; oral questions.

Quoting a job

A quote has four lines: parts, labour, small items (washers, grease, rags) and your margin. Write it down. Get the customer to agree before you start, and take a deposit for parts (a half is a common choice). If you find more faults, stop and tell the customer before you add cost.

Example quote (all numbers are examples, not real prices):

Parts sourcing

• No source for Takoradi parts shops or GH¢ prices for plugs, impellers, gear oil or propellers was found. Do a price survey (homework) rather than trust any number.
• Yamaha's agent in Ghana is Japan Motors Trading Co (JMTC), with a Takoradi branch among its branches; whether the Takoradi branch stocks outboard parts is not verified. Suzuki's Ghana distributor CFAO Motors delivered more than 1,000 Suzuki outboards in 2020. The GoAfrica directory lists "marine engines" firms, with parts and propellers, including coverage of Takoradi. Do not name a shop you have not visited.
• Ask for the engine model and serial number before you order a part. Check the part number against the maker's list. Take the old part with you.
• Keep a spare-parts kit of the cheap, fast-moving parts: plugs, gear oil, split pins, fuel filters, primer bulbs, washers and gaskets, impeller kits, propeller nuts. This is our suggestion for a small stock, based on the faults in Unit 5 (general practice, not verified).
• Genuine or compatible part, new or used: tell the customer which you fitted, and put it on the job card. The customer decides.

Job cards and records

Why hours matter. Honda says commercial users should log engine hours to set service intervals. Keep an engine history card for each regular customer: it helps you to see repeated faults and to plan next service.

Warranty

Write one short, honest promise on the job card, for example: "Parts fitted by me are guaranteed for 30 days against failure from my work. This does not cover damage from misuse, salt water, bad fuel or hitting an object." The 30 days is an example. Consumer-protection rules for repairs in Ghana: not verified. Never promise what you cannot do, and never say a fault cannot return.

Canoe registration and premix rules (Ghana)

What is verified.

• The Fisheries Commission issues the Canoe Identification Card (CIC): an embossed card with a QR code readable on a phone app; it shows the canoe's name, length, fishing village, gear type, whether it is motorised, and issue and expiry dates. It is valid six years and renewed every three years. It is checked during naval patrols and when premix is allocated. The programme was reported with a "no card, no sea" deadline of 1 January 2021 (as reported in 2020).
• The 2015 vessel registration regulations (L.I. 1968) exclude canoes as defined in the Fisheries Act 2002.
• Premix is subsidised fuel for artisanal fishing outboards. The official price from 1 September 2026 was GH¢5.51 a litre and GH¢24.80 a gallon. A landing beach committee that charges above the approved price faces, as reported, a penalty of up to two years' prison, 2,000 penalty units or both. The secretariat line reported in May 2026 was +233 55 442 0970. Subsidy: the NPA says up to 50%, price reviewed quarterly.
• Ethanol and four-stroke fuel: the four-stroke manual says E0-E10 only. A four-stroke engine must not run on premix (our inference from the manual; not a Ghana rule).

What is not verified.

• The fee and documents for a CIC; any rule on engine registration or horsepower limits for canoes; any rule from the Ghana Maritime Authority for canoes at sea. The GMA's 2026 statements concerned inland waters and a proposed lifejacket rule. Ghana's status under the ILO Work in Fishing Convention is not verified.
• The official oil ratio and quality control of premix, and Ghana's petrol ethanol content.
• Who may sell fuel or premix. Do not sell fuel or premix unless you have checked the rules with the NPA; it is not part of this trade (not verified).

What a mechanic should do. Ask a customer for the canoe card number on the job card if they have one. Advise on correct fuel, but do not give or sell premix. Never advise mixing pump petrol and diesel: reports say fishers do this when premix runs short, and it can destroy an engine. Do not repeat rumours or name individuals.

Check yourself

1. What four lines are on a quote?
2. What does the Canoe Identification Card show, and how long is it valid?
3. Can a four-stroke engine run on premix?

Competency standard

Range. A mobile mechanic, a service bay or a parts counter. Evidence. Business plan; break-even sums; oral questions.

What the market looks like

• Many coastal communities received subsidised outboard motors: for example, the Western Region got 300 of the first 1,300 in an older report (the date was not captured), and Jomoro received 58 Yamaha 40 hp motors. Suzuki's Ghana distributor delivered more than 1,000 outboards.
• The Canoe and Fishing Gear Owners Association of Ghana reported over 30 faulty-outboard-at-sea cases in the Volta, Greater Accra, Central and Western regions after fishing resumed on 1 August 2023. It blamed poor maintenance and fishing farther out, and advised servicing at least every six months and repairing small faults while the engine still runs.
• The number of motors at Akwidaa, labour rates and market prices were not found. Ask the chief fisherman or the canoe owners' group, and use your own price survey.
• A diploma route also exists: the Regional Maritime University in Accra has a Marine Engine Mechanic programme; intake details are not verified.

Location settings that give good returns

Business ideas and ingenuity

(These models are our own design, based on the demand shown above; they are not sourced business data.)

Money maths: break-even (example)

Suppose your fixed costs for a month are: data and phone GH¢60, transport to beaches GH¢240, tool replacement GH¢100, and a small market or beach fee GH¢40 (all examples). That is GH¢440 a month. Each job earns, on average, labour GH¢80 and parts margin GH¢30 = GH¢110. To break even you need 440 ÷ 110 = 4 jobs a month. If you do 22 jobs, your profit is 22 × 110 − 440 = GH¢1,980 (before tax; all numbers are examples). Business registration, tax and accounting are in Level 3.

Market yourself

• Use WhatsApp Business: a business profile with your hours, address, a catalogue of services and automatic greeting and away messages. Send photos (with permission) of before and after.
• Set up a free Google Business Profile so people searching nearby can find you; verification can be by phone, email, video call or a postcard that takes about 14 days.
• Put up a clear signboard: "Outboard motor repair and service," your name, phone and services in plain words and local languages.
• Referrals: ask satisfied owners to tell others. Give a small bag of spare plugs or a free check to a canoe-owner group leader (it is your decision).
• A portfolio: keep a book of job cards and photos (with permission).
• Be honest. Never say you are a dealer-trained or certified mechanic if you are not. Do not claim a guarantee you cannot meet.

Accessibility

The Persons with Disability Act, 2006 (Act 715) is the law on disability rights. It has employment provisions, including training and tools support for people unemployed more than two years, and bans discrimination at work. A 2026 press item says private-sector incentives are not yet working as intended. Exact section numbers were not verified. Reports said the Assemblies' disability share would rise to 5% from 2026; this was not verified for this book. Reports say public places still do not follow the Act fully. Ask your Assembly about help.

Tasks that may suit a person with a disability (our suggestions, not sourced; confirm with the person and an occupational therapist):

Adjustments that help: a bench at seated height; tool holders and magnetic trays; good light; picture checklists and large-print job cards; voice notes for people with low vision; written or visual signals instead of calling out for workers who are deaf; ear protection; short written steps. Do not state legal duties beyond the Act without checking it. Training for workers with disabilities should be given in a way each person can follow.

Check yourself

1. Name two good locations for an outboard repair business.
2. How do you work out break-even jobs?
3. Name one adjustment that helps a worker who is deaf.

1. Name the fuel path from the tank to the cylinder.
2. Why must you never poke a carburettor jet with wire?
3. How do you hold a plug cap during a spark test?
4. What do you do first if no water comes from the tell-tale?
5. Why must an outboard never be run without water?
6. Which gear-oil bolt do you remove first, and how do you fill the lower unit?
7. What does milky gear oil mean?
8. When must an anode be replaced?
9. In what order do you disconnect and connect a battery?
10. What readings does Yamaha give for a battery at rest and with the engine running?
11. How deep must the water be over the anti-ventilation plate in a test tank, and what must be off the engine?
12. Can a four-stroke engine run on premix?

Best next reads: your own engine's owner's manual (Tohatsu and Honda manuals are free from the makers; Mercury manuals are free by serial number); a licensed dealer's workshop manual; the FAO fishing-safety site; the Fisheries Commission; a local dealer for hands-on training.

What this module does not cover: engine rebuilds, ignition timing and carburettor adjustment (dealer jobs), fuel-injection diagnostics, hoisting and mounting an engine on a transom, beach launching procedure (no source found), business registration, tax and accounting (Level 3), and any make not read here (use the maker's manual).

Every source used in this manual is listed, with links, in the Teacher Copy.