Mercury outboards are one of the most reliable outboard brands out there.
This has led to a series of technological innovations in each new outboard series that they manufacture.
That is why in some of their new outboard motors you see EFI being used instead of the traditional carburettor.
This helps in giving a better position in fuel delivery to the combustion chamber to help reduce excess emissions and also increase engine performance.
But sometimes the Mercury 4 stroke EFI outboard bogs down under load when it has some problems.
Some of the reasons why Mercury 4 stroke EFI outboard motor loses power under load includes use of bad fuel, sensor problems, faulty ignition system, use of poor quality parts, overheating and other reasons like having a faulty exhaust system.
These problems contribute to performance lab when using your mercury 4-stroke EFI outboard motors.
Why Mercury 4 Stroke EFI Outboard Bogs Down Under Load
1)Sensor Problem
With the use of an EFI in an outboard motor most of the functionalities of the outboard motor becomes electronic.
This makes it easy for problems to be easily detected.
But sometimes most of these sensors can go bad.
When this happens the performance of the outboard motor will reduce.
This will lead to some issues while using your EFI outboard motor.
One of the ways this problems of having a bad sensor they show up is that it will be giving wrong information.
For example if the temperature sensor is faulty, the outboard motor will not be able to give an exact temperature of the outboard motor.
This can easily lead to overheating which reduces the power of the outboard motor.
Solution
1)Replace Faulty Sensor
While using your outboard motor, if you discover that one or more of the sensors are bad you have to make sure that you replace them.
To make this process a successful one, you have to make sure that you use the services of a qualified and well experienced technician.
This will help increase the performance of your outboard motor when these bad sensors are replaced with a good one.
2) Overheating
When it comes to the use of outboard motors, overheating or extreme temperature rise is always a very big problem.
When your EFI outboard motor is overheating, the performance of the outboard motor will reduce.
This reduction in power output from the engine will show when you try to throttle or increase the speed of the outboard motor.
During the speed increase, what you will observe is that your outboard motor will be struggling to match up with the RPM.
This is due to the power loss that is caused by the overheating outboard motor.
When overheating occurs in an outboard motor, it can be due to some reasons.
One of the reasons why an outboard motor with an EFI system overheats is usually due to a faulty cooling system.
This can be caused by a bad impeller or a clogged water hose that circulates water within the outboard motor.
Solution
1)Repair Faulty Cooling System
When you discover that the cooling system of your outboard motor is bad, you have to make sure that you replace it with a good one.
But before making the replacement, you have to troubleshoot to really determine the exact problem.
3) Faulty EFI System
EFI system is one of the biggest innovations in the outboard motor industry.
Due to its high functionality, it has easily replaced the use of traditional carburettor in a lot of modern outboard motors.
This is because of how effective the use of an EFI system is.
With the use of the EFI system, the delivery of fuel to the combustion chamber is well regulated.
This helps in avoiding cases of extreme emissions from the outboard motor.
It also helps in achieving better performance from the engine.
But sometimes they might develop a fault.
When these fault occur it will lead to a poorer performance of the outboard motor.
Solution
1)Replace Faulty EFI System
With the use of your outboard motor, a lot of parts are not going to last till eternity.
That is why at some point, you will discover that some of the parts have issues.
When this occurs the performance of the outboard motor will suffer when it comes to power output.
When the EFI in the outboard motor has a fault, the performance of the outboard motor will reduce.
With this, you will see noticeable negative changes like higher emissions, bogging of outboard motor while accelerating and other common issues that is linked to a faulty EFI system.
To correct this, you have to make sure that you replace the faulty EFI system with a good one.
4) Corossion Problems
Another reason why mercury 4 stroke EFI outboard bogs down under load is due to corrossion.
Corrossion is one of the problems that a lot of outboard motor users face.
This is due to the environmental condition in which the outboard motor is used.
In some locations, the water on which the outboard motor is being used is salty in nature.
The salty water reacts negatively with the outboard motor.
Due to such reactions like this, corrosion takes place.
When corrossion occurs in an outboard motor, it reduces the overall performance of the outboard motor.
Solution
1)Rinse Outboard Motor With Fresh Water After Use
While using your outboard motor on a salty water, the salty water will come inside the outboard motor.
This is due to the use of the salty water as a cooling medium to reduce the temperature of the outboard motor.
As time goes on with more exposure of the outboard motor to saltwater, corrosion starts to take place gradually.
But this corrosion can be easily avoided if a good maintenance culture is used after making use of the outboard motor.
This has to do with rinsing the outboard motor properly after use.
To do this in an effective and efficient way, you must make sure that you use in freshwater for rinsing.
This will help remove the salt water from the outboard motor and reduce the chances of corrosion occurring in the outboard motor.
5) Faulty Ignition System
Mercury 4 stroke EFI outboard motor loses power when accelerating under load due to faulty ignition system.
When it comes to the functionality of an outboard motor, the ignition system is a very important system.
This is due to the role the ignition system plays in the performance of the outboard motor.
For an outboard motor like the Mercury EFI outboard motors to perform well, the engine has to produce power.
But for the engine to produce power, there are some series of activities that should occur.
One of these activities include the ignition of fuel in the combustion chamber.
For fuel to be ignited in the combustion chamber of the outboard motor, the spark plug which is one of the ignition system components help in making this possible.
But the spark plug does not work alone to make this possible.
It depends on other ignition system components to achieve this.
Some of these parts of the ignition system components include the ignition coil as well as a spark plug cap.
Any damage to any of these components will reduce the efficiency in the performance of the mercury EFI outboard motor.
This performance lag is really going to show when you are accelerating your outboard motor.
With a faulty ignition system, the outboard motor will easily lose power and bog down when you are accelerating it.
Solution
1)Replace Faulty Ignition System Components
When you discover that your outboard motor is losing out in performance, you have to troubleshoot.
Some of the places you have to make sure that you troubleshoot is the oil level in the outboard motor since it has a separate compartment due to the fact that it is a four stroke outboard motor.
Apart from checking the oil level, you have to check for faults in one of the most important systems in the outboard motor which is the ignition system.
In troubleshooting the ignition system for a fault, you need to test the spark plug and make sure that it is functioning well and also check the ignition coil too.
If you discover any of the components that has a defect or faulty, you have to make sure that you change it.
This will help in improving the power output from the outboard motor.
With an increased power output from the outboard motor, you will not have problems when you are accelerating.
6) Use Of Poor Quality Fuel
Mercury 4 stroke EFI outboard bogs down under load if you use contaminated fuel.
The type of fuel to use in running your outboard motor place a huge role in how your outboard motor will perform.
Using a good fuel in running your outboard motor will always give you a flawless experience.
But when you make use of the contaminated and bad fuel to run your outboard motor, then performance will reduce.
One of the things that reduces the efficiency and quality of fuel used in the outboard motor is if you have kept the fuel for too long without use.
Another thing that can make an outboard motor fuel bad for use is when it contains water or dissolved particles in it.
These problems reduce the power generated by the outboard motor from the combustion chamber.
Solution
a)Use Good Fuel
If you want to enjoy a flawless performance anytime you are making use of your outboard motor, you should pay good attention to the quality of parts that tou use.
Also you have to make sure that you use a good quality fuel in running your outboard motor.
This will help achieve a good combustion in the combustion chamber thereby leading to the release of power from the outboard motor.
If you find out that the fuel that you want to use in your outboard motor has been staying for a long period of time without use, you have to make sure that you do not use it to run your outboard motor.
b) Use Water Seperator
What you use your outboard motor, there are chances that water might get into the fuel tank.
When this happens, the water in the fuel will be sent to the combustion chamber when fuel is also sent for combustion.
This will reduce the effect of combustion that takes place in the combustion chamber.
Due to this, the power released from the engine will be reduced.
To solve this problem of water in the fuel of an outboard motor, you have to make sure that you make use of a water separator.
This helps in removing water from the outboard motor fuel.
7) Faulty Exhaust
In a four stroke outboard motor engine, there are four phases of functionality.
The last face is usually the removal of toxic gases after combustion has taken place in the combustion chamber.
This helps in improving the performance of the outboard motor.
But if there is any problem with the exhaust system of the outboard motor, then the outboard motor will have some problems in performance.
One of the reasons why this happens is if the exhaust system manifold has a problem of leakage.
Solution
a)Fix Exhaust Problems
If after troubleshooting you discover that the exhaust system of your outboard motor is faulty, you have to make sure that you fix this problem.
The solution that you give depends on the problem that the exhaust system has.
If you discover that the exhaust system is being clogged with carbon, you have to make sure that you remove the carbon.
This will help in the easy discharge of the byproducts from the combustion chamber.
With this, your outboard motor will be able to function well even when it is accelerating.
8) Overloading
Mercury 4 stroke EFI outboard loses power when throttled under load due to overloading.
When an outboard motor is being used, bad practices like overloading should be seriously avoided.
This is because overloading reduces the efficiency of an outboard motor.
Apart from reducing the efficiency of an outboard motor, overloading also leads to a reduction in the lifespan of the outboard motor.
That is why it is not good to overload your boat.
But how can you know if you are overloading your boat or outboard motor if you don’t know the load limit.
With every outboard motor, there is a specific load it can comfortably carry.
With this load range the outboard motor will be able to easily reach a good top speed and RPM when accelerating.
But when an overloading occurs, this will not be possible.
That is why it is very important to make sure that you check the load capacity of your outboard motor.
This will help you avoid overloading when making use of your outboard motor.
Solution
1)Do Not Overload
If you want to make sure that your outboard motor is not overloaded, then you have to be very conscious of the load that you impose on your boat.
One of the ways of being very precise in doing this is to make sure that you know the exact peak load that your outboard motor can support.
This can also be seen in the capacity plate of the boat.
With this, the experience of mercury 4 stroke EFI outboard motor losing power under load will rarely occur.