MST MST Marine Fuel Systems 2

Question 1

What is the correct procedure to test a fuel system for leaks after a repair?

Accepted Answer

Pressurize with air to no more than 3 psi and check fittings with soapy water

Answer

Fill tank and visually inspect only

Answer

Run the engine and smell for fuel

Answer

Use an open flame near fittings to reveal vapor

Question 2

Phase separation in ethanol-blended gasoline (E10) stored in a marine tank causes what problem?

Accepted Answer

Water and ethanol separate from the gasoline and sink, leaning out the fuel mixture

Answer

The fuel becomes richer and runs better

Answer

No problems occur with E10 in marine engines

Answer

Only diesel fuel is affected by phase separation

Question 3

A two-stroke outboard engine is drawing in air through the fuel system; which component is the most likely cause?

Accepted Answer

Cracked or deteriorated fuel line or primer bulb

Answer

Clogged fuel filter

Answer

Stuck choke plate

Answer

Faulty tachometer sensor

Question 4

What is the function of the anti-siphon valve installed on a marine fuel system?

Accepted Answer

To prevent fuel from gravity-feeding into the engine when it is not running

Answer

To regulate fuel pressure to the injectors

Answer

To allow air into the tank for vapor equalization

Answer

To filter water from the fuel before it reaches the engine

Question 5

What color is the standard fuel fill deck fitting on gasoline-powered boats to distinguish it from diesel?

Accepted Answer

Red

Answer

Yellow

Answer

Green

Answer

Black

Question 6

When replacing a fuel filter on an EFI outboard engine, what precaution must be taken before disconnecting fuel lines?

Accepted Answer

Relieve fuel system pressure by running the engine until it stalls or using the service manual procedure

Answer

Disconnect the battery only

Answer

Remove the fuel cap to vent the tank

Answer

No special precaution is needed for EFI systems