The Johnson outboard motor comes with some level of reliability.
This has earned the company good level of patronage from boat users.
But sometimes Johnson outboard bogs down at full throttle while making use of them.
Some of the reasons why Johnson outboard motors lose power at full throttle includes overloading, overheating, use of bad fuel to oil mix ratio in the 2 stroke variant, use of bad spark plug and faulty ignition system.
When these problems occur, the power generated from the outboard motor will be reduced.
This will lead to an unpleasant boating experience.
How to overcome these johnson outboard motor issues will be discussed in this guide.
Why Johnson Outboard Loses Power At Full Throttle And How To Fix It
1)Faulty Carburetor
When it comes to how an outboard motor performs, the carburetor performs a key role in achieving any level of performance.
For an outboard motor to produce power, it needs to burn fuel mixture in the combustion chamber.
The amount of fuel it needs to burn depends on the mode it is operating in.
At an idle mode, the outboard motor will burn less fuel.
But when the outboard is in an accelerating mode, it will need to burn more fuel.
In each of these modes of operation, the fuel released to the combustion chamber has to be controlled.
This is made possible by the carburetor in the Johnson outboard motor.
The carburetor helps in releasing the right volume of fuel to the combustion chamber.
This helps the engine to produce the power needed by the outboard motor especially when it is accelerating.
But if the carburettor is faulty, this will not be possible.
A faulty Carburetor can be stuck in the closed position which releases less to no fuel.
This leads to fuel starvation in the outboard motor combustion chamber.
As a result of this, the outboard motor will bog down when accelerating due to its inability to produce power that matches the speed level.
This leads to a reduction in the performance of the Johnson outboard motor.
Solution
a)Rebuild Faulty Carburetor
When you discover that the carburetor in your outboard motor is faulty, you need to rebuild it.
In rebuilding the faulty carburetor, make sure that the faulty parts are replaced with compatible ones.
If not, problems will still arise when you make use of the rebuilt carburetor.
2) Fouled Spark Plug
Having a fouled plug is one of the issues some outboard motor owners experience.
When this happens, the productivity of the spark plug will be reduced.
The fouling of a spark plug can be caused by oil when the oil covers the tip of the spark plug that produces the spark.
Fouling of spark plug can also be caused by carbon when there is too much carbon in the combustion chamber.
This creates a layer on the top of the spark plug making it difficult for the spark plug to ignite fuel mixture easily in the combustion chamber.
Solution
a)Use Correct Fuel To Oil Mix Ratio
One of the things that causes fouling of a spark plug is when there is too much oil in the combustion chamber.
With this excess oil, efficient combustion will not be able to take place in the combustion chamber.
This is worse in the case of a two stroke outboard motor.
This is because when there is too much oil in the fuel mixture for a 2-stroke outboard motor, the fuel mixture will become less volatile.
This will make the spark plug struggle to produce enough charge to efficiently burn the fuel mixture.
Due to this, incomplete combustion will take place.
When incomplete combustion takes place in the combustion chamber, smoke will be really released.
Apart from the smoke being released through the exhaust pipe, some of it will remain in the combustion chamber.
This causes the carbon to cover the tip of the spark plug which leads to fouling of the spark plug.
This will reduce the efficiency and performance of the outboard motor.
b)Clean Fouled Spark Plugs
When a spark plug is covered with carbon, the performance of the spark plug in easily igniting fuel mixture in the combustion chamber will be reduced.
This will cause a significant reduction in the power produced from the outboard motor.
To help correct this problem, you have to make sure that you take out the spark plug and clean it.
This involves dipping the spark plug in a fuel that is free from contaminants and oil.
This will help shed out the carbon from the spark plug.
After rinsing it in fuel, make sure that you leave it to dry properly before putting it back into your outboard motor.
b) Replace Bad Spark Plugs
If you discover that a spark plug that has been fouled is not producing enough electric charge when you test it, you have to change it to a good one.
3) Contaminated Fuel
For your outboard motor to function, the presence of fuel is very important.
This is because fuel is what the combustion chamber will ignite to produce power.
But to make the combustion process efficient, you have to make sure that the fuel that you use in your outboard motor is not a contaminated fuel.
If the fuel is contaminated by things like water or dissolved particles, then the ease at which it can be combusted in the combustion chamber will be reduced.
This will affect the performance of the outboard motor.
This will lead to situations in which Johnson outboard bogs down at full throttle.
Solution
a)Use Good Fuel
When you discover that your outboard motor is lagging in performance due to the use of contaminated fuel, you have to make sure that you change the fuel to a good one.
But in changing the fuel, make sure that you do not use fuel that has stayed for too long without use.
A stale fuel will also cause performance reduction when your outboard motor is functioning.
That is why fresh and premium fuel is always really recommended if you want to achieve a good performance from your johnson outboard motor.
4) Bad Fuel To Oil Mix Ratio
In a 2-stroke Johnson outboard motor, the use of oil does not work like the 4 stroke variant..
In the four-stroke Johnson outboard motors, a separate compartment is provided for oil to be filled.
But when it comes to the use of a 2-stroke Johnson outboard motor, you have to manually mix the oil with the fuel before introducing it into the gas tank.
It is at this point of mixture that determines if your Johnson 2-stroke outboard will perform well or not.
This is because if You use too much oil in the fuel mixture, there will be issues like smoking and low performance from your outboard motor.
If you also use less amount of oil in the fuel mixture, your outboard motor will also suffer performance lag and will always have a knocking sound.
To avoid these problems, you have to make sure that you use the right mix ratio that is meant for 2-stroke Johnson outboard motor.
This correct mix ratio is 50:1.
This simply means that for every 50 litres of fuel, you have to add 1 litre of oil to the fuel mixture.
With this, you will have a flawless and good performance when making use of your 2-stroke Johnson outboard motor.
Solution
a)Use Good Mix Ratio
In some situations, reduction of power in outboard motor performance will occur due to wrong mix ratio of fuel and oil.
That is why you have to make sure that you use a correct and good mix ratio.
This will help your Johnson outboard motor perform well especially when you are accelerating.
To achieve this, you have to make sure that you use recommended mix ratios like 50:1.
5) Low Compression In Cylinder
For your Johnson outboard motor to function well, it has to maintain some level of compression in the cylinder.
This compression is what helps the pressure that is built during ignition of the fuel mixture to push down the piston thereby generating a circular motion that is transmitted to the propeller to function well.
But if you have a low compression in the cylinders of your Johnson outboard motor, then you will experience power loss.
This power loss will really show up in situations when you are increasing speed.
When a low compression occurs in a cylinder, it can be due to situations like cracked engine block or damaged pistons.
Solution
a)Rebuild Engine
When you discover that you are having a low compression in the cylinders of your Johnson outboard motor, you have to make sure that you fix it very fast.
This will help ensure better performance when you make use of your outboard motor again.
6) Damaged Fuel Line
Before fuel gets to the carburettor of a Johnson outboard motor, it has to pass through a channel.
This channel is usually the fuel line that connects the gas tank to the fuel pump.
For the fuel line to help your outboard motor to function well, it must exist without flaws.
This will help in maintaining the pressure that the fuel pump creates to move the fuel from the gas tank to the carburettor.
But if the fuel line is not functioning well like having a cut, leakage of the fuel and leakage of pressure in pumping fuel from the gas tank will be reduced.
This will affect the performance of the outboard motor in a negative way.
Solution
a)Use Good Fuel Line
If you have a faulty fue line that you make use of in your Johnson outboard motorand you observe that your outboard motor is not functioning well, you have to make sure that you replace it with a good one.
In replacing it with a good one, you have to make sure that the quality of the new one is good.
This will help the fuel line to easily transmit fuel from the fuel tank to the fuel pump.
With this, the fuel pump will be able to supply the right volume of fuel that is needed.
7) Overloading
Overloading is a very big problem that can reduce the performance of any outboard motor.
Every outboard motor manufacturer has a certain limit of load that can be imposed by a boat that is using a particular outboard motor.
That is why this load limit is always specified by the boat manufacturers.
This is to help achieve a better performance whenever you are making use of your Johnson outboard motor.
But if you exceed this load limit that the outboard motor can easily carry, the performance of the outboard motor will reduce.
Overloading is one of the reasons why Johnson outboard motor loses power at full Throttle.
That is why you have to make sure that you load your boat to an acceptable range that the outboard motor can carry.
Solution
a)Avoid Overloading
Before having any boat trip, you have to make sure that you weigh all the total load that will be imposed on the boat and outboard motor.
In doing this, make sure that you do not exceed the load limit that the outboard motor can accommodate.
This will help avoid overloading which will also help the outboard motor to function effectively without power loss when throttling.
8) Lack Of Timely Maintenance
For a Johnson outboard motor to function well, timely maintenance should not be missed.
This is because it is during the maintenance period that some of the flaws of the outboard motor is usually seen.
It could include things like changing the oil or other things that changing a damaged part.
This helps in avoiding an extending damages of the faulty part to other components of the outboard motor.
But if a timely maintenance of the outboard motor is not carried out, the outboard motor will suffer severe damage that will reduce it’s power when accelerating.
Solution
a)Perform Timely Maintenance
There’s a particular duration that is specified by all manufacturers for maintenance of your outboard motor.
When this period of time reaches, you have to make sure that you perform maintenance on your Johnson outboard motor.
This will help show some of the parts that are faulty that may need to be repaired or replaced completely with a new one.
When this is done, the productivity and functionality of the outboard motor will improve.
9) Faulty Fuel Pump
The fuel pump in a Johnson outboard motor is a very important part of the outboard motor.
This is because it helps in supplying fuel to parts like the carburettor by pumping out fuel from the fuel tank.
But if the fuel pump is faulty, the performance of the Johnson outboard motor will be reduced also.
One of the signs of a faulty fuel-pump is that it will release less volume of fuel that is not adequate for the full functionality of the outboard motor.
To troubleshoot this, you can take off the hose that connects the fuel pump to the carburettor and try to start the outboard motor.
If the volume of fuel that comes out from your fuel pump is too small, then you know that the fuel pump is faulty.
With this, you have to make sure that you change it to a good one that is of the right capacity with your Johnson outboard motor.
Solution
a)Use a Good Fuel Pump
When you discover that the fuel pump in your Johnson outboard motor is not functioning well, you have to make a replacement of it.
This will help your Johnson outboard motor to have a good performance when you make use of it again after changing the faulty fuel pump.
This will help eliminate cases in which the Johnson outboard bogs down at full throttle.