Alabama Boaters Engine Basics 5 — Questions and Answers
Question 1: What is the recommended action if your outboard engine's water tell-tale stops flowing while underway?
- Increase throttle to boost water pressure
- Reduce speed and shut off engine to investigate possible water pump failure (Correct answer)
- Switch to reserve fuel tank
- Tilt the engine fully up and continue slowly
Correct answer: Reduce speed and shut off engine to investigate possible water pump failure
Loss of the tell-tale stream indicates the water pump may have failed; continuing to run the engine risks severe overheating and permanent damage.
Question 2: How does a kill switch (engine cut-off switch) enhance boater safety?
- It prevents the engine from starting if the fuel tank is low
- It automatically stops the engine if the operator is ejected from the helm position (Correct answer)
- It cuts fuel flow when the bilge pump activates
- It disables the starter motor in shallow water
Correct answer: It automatically stops the engine if the operator is ejected from the helm position
The kill switch lanyard, attached to the operator, cuts the engine immediately if the operator falls overboard, preventing the unmanned boat from circling and striking them.
Question 3: What is the significance of an engine's 'compression ratio'?
- It measures how many liters of fuel the tank holds
- It indicates the ratio of cylinder volume between bottom and top of piston stroke, affecting power and efficiency (Correct answer)
- It determines how many spark plugs the engine requires
- It specifies the maximum oil pressure the engine can sustain
Correct answer: It indicates the ratio of cylinder volume between bottom and top of piston stroke, affecting power and efficiency
Compression ratio is the ratio of the cylinder's maximum volume to its minimum volume; higher ratios generally produce more power and efficiency but require higher-octane fuel.
Question 4: Which maintenance step helps prevent corrosion on an outboard motor's electrical connectors?
- Coating connectors with engine oil after each use
- Applying dielectric grease to connectors (Correct answer)
- Rinsing connectors with saltwater to neutralize acids
- Covering connectors with silicone rubber sealant permanently
Correct answer: Applying dielectric grease to connectors
Dielectric grease is a non-conductive compound that seals out moisture and oxygen from electrical connectors, preventing corrosion without interfering with electrical contact.
Question 5: What happens to engine performance when a fuel filter becomes clogged?
- Engine runs faster due to higher fuel pressure
- Fuel flow is restricted, causing power loss, rough running, or stalling (Correct answer)
- Oil consumption increases significantly
- Spark timing advances automatically
Correct answer: Fuel flow is restricted, causing power loss, rough running, or stalling
A clogged fuel filter restricts fuel flow to the engine, resulting in fuel starvation that causes hesitation, power loss, or complete engine stall.
Question 6: In marine engines, what is the primary role of the alternator or stator?
- Start the engine by spinning the crankshaft
- Charge the battery and power electrical accessories while the engine runs (Correct answer)
- Regulate water flow through the cooling jacket
- Control ignition timing electronically
Correct answer: Charge the battery and power electrical accessories while the engine runs
The alternator (or stator on smaller outboards) generates electricity when the engine runs, replenishing the battery and supplying power to lights and electronics.
Question 7: What precaution should be taken when storing a boat with a gasoline engine for more than 30 days?
- Drain all coolant from the engine block
- Add a fuel stabilizer to the tank and run the engine briefly to distribute it (Correct answer)
- Remove the battery and store the engine with a full oil sump
- Seal the exhaust ports with tape to prevent moisture entry
Correct answer: Add a fuel stabilizer to the tank and run the engine briefly to distribute it
Fuel stabilizer prevents gasoline from oxidizing, forming varnish deposits, or absorbing moisture during storage, protecting the fuel system and carburetor or injectors.
Alabama Boaters Engine Basics 5
What is the recommended action if your outboard engine's water tell-tale stops flowing while underway?