Basic troubleshooting guide

Troubleshooting

The below trouble shooting chart has been taken from the Tohatsu Owner’s manual as an example and has been provided as a guide.

Motor troubleshooting guide examples

This guide applies some of the examples provided in the above chart and information provided as part of the practical components of the learning throughout the course and information on the functions of different components of the motor detailed in this manual.

The three main components that a two-stroke motor needs to run are:

• FUEL
• SPARK
• COMPRESSION.
  

It also needs water to provide cooling for the motor as part of the combustion process (generation of energy). If a motor has all of these then it should start.

Scenario 1

Motor doesn’t start

The following guidelines take you through a process covering these three main components and how to check them. Should the motor still not start after completing this process then contact your Service Agent.

• Check the IRB log to see if the motor has been recently submerged as there may still be some residual water in the carburettor and another reinstatement may be necessary.
• There must be reasonable resistance (compression) on both cylinders when you pull the motor over.
• Check choke mechanism is engaging correctly (butterfly is opening and closing).
• Check fuel is getting to the carburettor (primer bulb is tight) and fuel is fresh.
• If you have flooded the motor and can see/smell overflow of fuel then push choke in, place kill switch in the ‘run’ position, apply full throttle, and pull motor over using two hands to generate a high-speed pull. If motor starts after around 6-8 pulls, hold throttle on until the motor clears surplus fuel, then back off the throttle and allow motor to idle.

If the motor still does not start:

• Remove spark plugs and replace them with a new set.
• If reusing existing plugs, clean and dry then check for a healthy spark by connecting the HT lead to the plug cap and, using insulated pliers, earth the plug onto the powerhead block (well away from spark plug holes). With kill switch in the ‘run’ position, pull motor over to generate spark. Repeat this process with the other plug and HT lead.
• If no spark is found, replace plug(s) and check for spark again.
• If no spark is found, the issue is likely to be with the kill switch
• Replace kill switch and check for spark
• If no spark is found, the issue is likely to be with the HT Leads, Coil pack or magneto
• Refer to the IRB Officer.

!Ensure any spilt/surplus fuel around the motor powerhead is washed away before testing for spark as the fuel may ignite resulting in a fire.

Scenario 2

Motor won’t idle

Check the fault-finding chart and progressively eliminate as follows:

• Check fuel is getting to the Carburettor (primer bulb is firm) and fuel is fresh.
• Check the fuel line connection to the motor. The Bayonet may not be correctly connected and can give you a firm primer bulb.
• Check the fuel line clamps – as loose clamps will allow air to be drawn into the fuel system
• Check the fuel tank lines for kinks
• Check idle adjustment. The idle adjusting screw is spring loaded and can back off from time to time.
• Check the spark plugs are clean
• Check the fuel filter for contamination
• Check the Carburettor for contamination

There are other causes of poor idle but the above are the most common causes.

Scenario 3

Poor motor acceleration on leaving the beach

The likely cause is either fuel or spark plug related.

Check the fault-finding chart and progressively eliminate as follows:

• Check fuel is getting to the Carburettor (primer bulb is firm) and fuel is fresh.
• Check the fuel line connection to the motor. The Bayonet may not be correctly connected and can give you a firm primer bulb.
• Check the fuel line clamps – as loose clamps will allow air to be drawn into the fuel system
• Check the fuel tank lines for kinks
• Check the spark plugs are clean
• Check the fuel filter for contamination
• Check the Carburettor for contamination

There are other causes of poor motor performance but the above are the most common causes.

Scenario 4

Poor motor acceleration post extended idling

The likely cause is a fouled spark and typically a short run at high motor speed will clear the fouled plug as extended idling can cause oil to build up on the plugs.

If the poor performance continues post a run at high motor speed, return to shore and follow the fault-finding chart and progressively eliminate as follows:

• Check fuel is getting to the carburettor (primer bulb is firm) and fuel is fresh.
• Check the fuel line connection to the motor. The bayonet may not be correctly connected and can give you a firm primer bulb.
• Check the fuel line clamps – as loose clamps will allow air to be drawn into the fuel system
• Check the fuel tank lines for kinks
• Check the spark plugs are clean
• Check the fuel filter for contamination – particulate or water
• Check the Carburettor for contamination – particulate or water

There are other causes of poor motor performance but the above are the most common causes.

Scenario 5

Motor overheats – no water from telltale.

The likely cause is a blocked or fouled water intake due to weed or operating in shallow or aerated water (lots of cavitation being experienced).

If clearing the weed/obstruction and returning the motor to deeper water does not remedy the problem, stop the motor and follow the fault-finding chart and progressively eliminate as follows:

• Check that the motor drive shaft has not been sheared – if the drive shaft has sheared, while you will be able to select forward and reverse at the gear selector you will not be able be able to get the IRB to move forward or backwards as there will be no drive to the gearbox.
• Check if water is exiting from the exhaust port on the Leg. If water is exiting the exhaust port on the upper leg it is likely that the telltale outlet is blocked, and the issue is not with the water pump.
• Check that the telltale outlet is clear. This will require the short length of tube being removed from the power head and then checking for debris.

• Check the tale motor-casing outlet and clear as required.

• Check fuel / oil mixture is correct. Typically, insufficient oil in the fuel will cause overheating of the motor due to a lack of lubrication.
• Check the fuel line clamps – as loose clamps will allow air to be drawn into the fuel system causing the motor to run lean which causes the motor to run hot.

There are other causes of motor over heating but the above are the most common causes.