Driving an outboard motor can be so much fun.
But these outboard motors do not exist without problems.
That is why mercury 40 hp 2 stroke problems is not a new thing to a lot of outboard motor owners.
This is because it is a man made product that cannot last forever without having some faults.
Some of the problems with mercury 40 hp two stroke outboard motor include smoking, overheating, engine knock, propeller damage and inability to start.
Irrespective of the problems that outboard motors face, the good news is that they can all be repaired.
This guide will enlighten you of mercury 40 hp 2 stroke outboard motor issues and how to fix them easily.
Mercury 40 HP 2 Stroke Problems And Solutions
1) Mercury Outboard Motor Not Starting
Having an outboard motor that refuses to start can be very disappointing.
This is usually due to a lot of factors.
It could be caused by too much oil in the fuel mixture, bad spark plug or even a bad stator or ignition coil.
When they occur, you have to be able to troubleshoot properly.
This will help you see the cause of the problem and how to easily fix it.
Causes
a) Too Much Oil In Fuel Mixture
When it comes to the use of oil in a 2 stroke engine, it is totally different from a 4 stroke engine.
In 4 stroke engines, there is a seperate compartment for oil.
This helps the outboard motor to function well without issues of less or excess oil in fuel.
But in the case of a 2 stroke, the case is different.
In a 2 stroke outboard motor, you have to mix oil with fuel.
In doing so, you have to make sure that you use the right mix ratio or face issues with performance.
If the oil in the fuel is too much, then you will have issues in which your outboard motor will be unable to start.
This is because too much oil in a fuel mixture makes it harder for the spark plug to ignite the fuel.
Due to this, the outboard motor will refuse to start.
b) Bad Spark Plug
For an outboard motor to start, the engine has to function and produce power.
This is possible through combustion in the combustion chamber.
But for this combustion to take place, the spark plug has to produce a quality spark for combustion to take place.
If the spark plug is bad, then the spark will not be efficient.
This will result in no combustion in the combustion chamber.
Due to this, the mercury 2 stroke 40 hp will not start.
c) Bad Carburetor
For an outboard motor to start, a carburetor plays a vital role.
this is because the carburetor is what will help supply the fuel for combustion.
If the carburetor is bad, then it will not be able to supply the needed volume of fuel.
A bad carburetor can be releasing less fuel.
A bad carburetor can also release excess fuel thereby leading to engine flooding.
Due to this, the outboard motor will not be able to start.
Solution
a) Use a Good Oil To Fuel Ratio
If you want to have a flawless start with your mercury 2 stroke 40 hp, you have to use a good oil to fuel mix ratio.
The optimal one you can use is the 50:1 fuel to oil mix ratio.
This will help your outboard motor to start effortlessly.
b) Use a Good Spark Plug
combustion is very necessary before an outboard motor can start.
Without it, then there will be no starting.
But for a combustion to take place, the spark plug has to be good.
If the spark plug is bad, then make sure that you change it to a good one.
c) Keep Carburetor Free From Debris
The carburetor helps supply fuel for combustion.
But as you continue in the use of your outboard motor, debris will accumulate in the carburetor.
This is usually due to the use of poor quality fuel.
This accumulated debris will end up limiting the flow of fuel and will affect the outboard motor when starting.
To correct this, you have to clean debris from the carburetor or replace with a new one if the damage is severe.
2) Mercury Outboard Motor Vibrating When Accelerating
While making use of your 2 stroke mercury 40 hp, you may experience some vibrations.
This is always very uncomfortable.
It also affects the performance of the outboard motor and may lead to the damage of some parts.
That is why you have to fix it quickly when it occurs.
Causes
a) Bad Fuel To Oil Ratio
Poor fuel to oil mix ratio is a very serious issue in the use of 2 stroke outboard motor.
When in excess, your outboard motor will perform poorly.
When the oil is inadequate, there will be poor performance too.
This will show up in outboard motor vibrations when accelerating.
b) Bad Spark Plug
For an outboard motor to move well especially when accelerating, combustion has to be efficient.
This will help deliver the needed power.
But for this to be possible, the spark plug has to good to ignite the fuel oil mixture in the combustion chamber.
if the spark plug is bad, then the cylinders will not produce efficient power.
This will result in vibrations when you are accelerating your outboard motor.
Solution
a) Use Good Fuel To Oil Ratio
To achieve a great performance when using a 2 stroke outboard motor, you have to use a good fuel to oil mix ratio.
For an optimal performance, use the 50:1 mix ratio.
This will help your outboard motor to perform well and avoid vibrations when accelerating.
b) Use a Good Spark Plug
For your outboard motor to produce an efficient power, then it has to burn the oil fuel mixture efficiently too.
For this to be possible, the spark plug has to be good and equal to the task.
If the spark plug is faulty, then the power generated from the outboard motor will be low.
This causes vibrations when a higher power is needed during acceleration of the outboard motor.
To fix this, you have to make sure that you replace a faulty spark plug with a good one.
3) Outboard Motor Smoking
Smoking of an outboard motor is very bad.
It can cause damage to the passengers of the boat and to the outboard motor too.
That is why you have to make sure that you fix it when it occurs.
This is one of mercury 40 hp 2 stroke problems that exist.
Causes
a) Too Much Oil In Fuel
When a 2 stroke outboard motor smokes, one of the major culprits here is usually poor fuel to oil mix ratio.
In this case of smoking, the oil is usually in excess.
This makes the spark plug not to burn the fuel mixture well and leads to incomplete combustion.
Due to the incomplete combustion, there will be smoke release from the outboard motor.
b) Poor Quality Of Oil
Apart from having too much oil in the fuel mixture, you can use a good mix ratio and still have a smoking outboard motor.
This is usually caused by an inappropriate oil or bad quality oil.
This causes the fuel oil mixture to be too viscous which makes it hard for the spark plug to achieve an efficient combustion.
Due to this, the outboard motor will smoke.
Solution
a) Use a Good Fuel To Oil Mix Ratio
To solve a smoking issue in a 2 stroke outboard motor, you have to make sure that you use the right fuel oil mix ratio.
This will eliminate the chances of having too much oil in the fuel mixture.
As a result of that, your 2 stroke outboard motor will not smoke.
b) Use a Good Quality Oil
When buying oil to mix with fuel for use in a 2 stroke outboard motor, use a good oil.
That is why you have to make sure that you buy from authorized distributors.
This will reduce the chances of buying a fake one.
Also make sure that it is the right type of oil to be used in your outboard motor.
This will help avoid smoking when using a 2 stroke outboard motor.
4) Propeller Damage
One of the faults in a 2 stroke mercury 40 hp is propeller failure.
The propeller is a major part in an outboard motor.
Without it, there can be no movement of the boat.
That is why you have to make sure that you take good care of it when in use.
Causes
a) Poor Storage
When you are done boating, the right thing to do is always to store your boat and outboard motor.
But in some of the storage times, this can cause problems to your outboard motor.
This happens when you store your outboard motor badly.
In such a scenario, the outboard motor parts like the propeller will be damaged.
b) Use In Rocky Water
Boating is done on the water surface.
But what is important to note is that not all boats can be used in all types of water.
Some water bodies will cause harm to the outboard motor parts.
An example of this is a rocky water.
When using an outboard motor on a rocky water, you risk the damage of your propeller.
c) Use In Extremely Shallow Water
When boating, do not operate on water bodies that are too shallow.
Extremely shallow water bodies will expose the propeller to the bottom of the water body bed.
This will lead to the accumulation of dirt into the propeller.
Also the propeller will hit the bottom of the water body and cause damage to the propeller.
Solution
a) Store Outboard Motor Well
When you are storing your outboard motor, you have to store it well.
In doing so, you have to store it in a place that it can be easily seen and not in a stuffed place.
This will help avoid damage to the propeller when the outboard motor is being stored
b) Avoid Rocky Water
To increase the longevity of your outboard motor, you have to make sure that you avoid rocky waters.
Rocky waters destroy the propeller when the propeller comes in contact with a rock.
To avoid such damage on the propeller, you have to avoid boating on rocky waters.
c) Avoid Extremely Shallow Water
When boating, you have to be mindful of the height of water from the water bed.
If the water body is too shallow, you have to avoid boating on such water bodies.
This will avoid damage of the outboard motor propeller due to weed entanglement or contact with water body bottom.
5) Propeller Pushing Out Too Much Water
Another mercury 40 hp 2 stroke problems is pushing excess water above water surface.
This usually impacts the performance of the outboard negatively.
When this occurs, then the propeller will not be able to generate enough force from the water to push the boat well.
This will cause the boat not to reach good speed levels.
Causes
a) Outboard Mounted Too High
When you see a propeller pushing out too much water, there is usually one common fault.
This is always due to wrong height of positioning the outboard motor.
When the outboard motor is positioned too high, it will be pushing out too much water.
Solution
a) Mount Outboard At The Right Height
When you discover that your outboard motor is pushing out too much water, you have to watch out for the height of mounting.
To get the best height for optimum performance of the outboard motor, you have to use manufacturers recommendation.
This will help position the outboard motor well.
And as a result of this, your outboard motor will perform well and displace less water above the water surface.
6) Engine Knock
Having a good fuel to oil mix ratio in an outboard motor is very important.
When there is less oil in the fuel mixture, then an engine knock is very close.
An engine knock occurs in a 2 stroke outboard motor when there is less or no oil in the fuel mixture.
That is why you have to make sure that you use a good fuel to oil mix ratio always.
Causes
a) Poor Oil To Fuel Mix Ratio
When there is less oil in the fuel you use in your 2 stroke outboard motor, an engine failure is close.
One of the ways in which this will show up will be in the sound of the engine when running.
In a fuel mixture where there is no oil or less oil in it, the sound of the outboard motor will be very loud and rough with knocking sound.
Solution
a) Use a Good Oil To Fuel Mix Ratio
To avoid knocking of a 2 stroke outboard motor, you have to make sure that there is adequate oil in the fuel mixture.
This will help in lubrication during combustion to help the pistons move well.
If you use a fuel oil mix ratio with less oil and encounted a knocking sound in your outboard motor, you have to use a good mix ratio.
In such a case, you can switch to the 50:1 fuel to oil ratio.
This will help your outboard motor to perform well without knocking.
7) Outboard Overheating
Overheating is another mercury 40 hp 2 stroke problem.
When there is an overheating of an outboard, a lot of components can be easily damaged.
That is why you have to make sure that you erase the chances of an overheating occuring in your outboard motor.
Causes
a) Faulty Cooling System
When the outboard motor is functioning, there is always a lot of heat generation going on.
But this heat is quickly reduced by the cooling system.
This is made possible by the impeller which pumps cold water into the outboard to help keep the temperature down.
But when any of the cooling system components get faulty, then there will be an overheating.
Solutions
a) Replace Or Repair Faulty Cooling System
To solve an overheating problem in your outboard motor, you have to make sure that the cooling system is working well.
If you discover that your outboard motor is overheating, then perform a check in the cooling system too.
It could be that the water transfer hose is bad or clogged with debris or that the impeller is bad.
When you discover any of these faults, replace with a good one.
This will help solve the overheating problem.
8) Sluggish Performance
A sluggish performance can be experienced at some point as one of the issues with mercury 40 hp 2 stroke.
It is usually caused by a lot of things.
It can be due to too much oil in the fuel mixture or bad spark plug.
It can even be caused by a loose throttle cable or when the outboard is mounted too high.
The important thing is that you have to diagnose the cause and fix it when it occurs.
Causes
a) Bad Spark Plugs
When the spark plug is bad, then the performance of the outboard motor will be negatively affected.
This will lead to the generation of lesser power.
As a result of this, the outboard motor will be sluggish in performance.
b) Loose Or Bad Throttle Cable
For an outboard motor to move faster, a communication has to be made by the operator to the outboard motor.
This communication is made possible through a link.
This link is the throttle cable.
But when the throttle cable is loose, then the outboard motor will be sluggish in movement.
c) Excess Oil In Fuel
You have to watch out for the vollume of oil you use in your fuel mixture when using a 2 stroke outboard motor.
Excess oil will inhibit the performance of the outboard motor.
This is because with too much oil in the fuel mixture, the fuel mixture will be too viscous and less volatile.
This makes it hard for the spark plug to efficiently burn the fuel mixture.
As a result of this, there will be a sluggish movement when using the outboard motor.
d) outboard Motor Height Of Positioning
For you to get a good performance from your outboard motor, then it has to be well positioned.
But if it is badly positioned, the performance will be less.
One way this happens is when the outboard motor is mounted too high.
When it is mounted too low, you will have performance issues too.
e) Bad Carburetor
The carburetor is a very vital part of an outboard motor.
It helps in sending fuel for combustion.
it also sends the right volume of fuel needed at different performance levels.
If it gets bad, then the performance of the outboard motor will be poor.
Solutions
a) Use Good Spark Plugs
To have a good performance from your outboard motor, the engine has to perform well.
What helps in this is the quality of spark plugs used.
A bad performance will occur when you use a bad spark plug.
To avoid this, you have to make sure that you use a good spark plug.
b) Keep Throttle Cables At Optimum Tension
For the carburetor to function well and release the right volume of fuel, the throttle cable has a part to play.
When the outboard motor is accelerating, the throttle cable is held with more pressure.
This prompts the carburetor to release more fuel in order to produce more power from the engine.
But when the throttle cable is bad, this will not be possible.
Due to this, the outboard motor performance will be affected negatively.
To correct this, you have to give proper tension to the throttle cable or replace it with a good one if it is bad.
c) Use a Good Oil To Fuel Mix Ratio
To get a better performance from your 2 stroke outboard motor, you have to use a good oil.
This will help the fuel mixture to boost the performance of the outboard motor.
In getting a good oil, buy from authorized dealers.
d) Position Outboard Motor Well
An outboard motor irrespective of the number of cylinders it has will not perform well when badly positioned.
This can occur when it is mounted too high.
It can also occur when it is mounted too low.
To avoid this and have a better outboard performance, make sure that you mount the outboard motor at the right height.
e) Use a Good Carburetor
If you want to enjoy a good outboard performance, a good carburetor is a non negotiable requirement.
The carburetor helps in supplying the needed volume of fuel at various levels of performance.
When the outboard motor accelerates, the carburetor supplies more fuel to keep up with the power demand from the outboard motor.
But if the carburetor is bad, it will not be able to keep up with the fuel demand.
This will lead to cases like outboard vibration or total shut down of the outboard motor.
To avoid this, you have to make sure that you are running your outboard motor with a good carburetor.
This will help eliminate mercury 40 hp 2 stroke problems caused by a bad carburetor from occurring.