Mercury outboards are known to be good and reliable by a lot of boat users.
This comes from their consistency in producing great outboard motors.
But sometimes mercury outboard bogs on acceleration which is always an unpleasant experience.
Some of the reasons why mercury outboard bogs when throttling includes EFI problems, faulty Carburetor, bad ignition system, faulty fuel filter and even problems like overloading.
These problems reduce the efficiency of the mercury outboard motor.
In this guide, you will learn of how to fix these problems easily to help enjoy your boating experience.
Causes Of Mercury Outboard Bogs On Acceleration Or Throttling With Solutions
1)EFI Problems
The outboard motor industry has experienced a high level of technilogical innovation.
This level of innovation comes in a lot of ways.
One of the ways in which this innovation is made is in how some newer technologies have replaced older technologies.
A clear example of this is in the use of EFI system to replace carburetors.
In most modern outboard motors made by mercury, you will discover that they make use of EFI and not carburettors.
This makes the introduction of fuel to the combustion chamber electronically controlled.
This has helped increase the fuel efficiency of mercury outboard motors.
Irrespective of the diverse advantages that this new technology carries, it still has some flaws.
These flaws show up when the EFI system does not function very well.
When this occurs, they will be powerless and the performance of the outboard motor will be reduced.
This will lead to a reduction in the volume of fuel that is being sent to the combustion chamber.
In such a scenario one of the things that the boat operator will experience is that the boat will lose out in performance when accelerating.
Solution
a)Replace Faulty EFI
When the EFI being used in your mercury outboard motor is not functioning well, you will have a performance lag.
A faulty EFI system can lead to consumption of more fuel.
In other cases, it can lead to the starvation of the combustion chamber from getting the right volume of fuel needed.
This is one of the reasons why mercury EFI outboard bogs on acceleration.
This reduces the efficiency of the outboard motor and produces less power.
To correct this, you have to make sure that you replace the faulty EFI with a good one.
2) Faulty Carburetor
In most modern mercury outboard motors, what you are going to find is an EFI system being used.
But in older mercury outboard motors, you will still find carburettors being used.
What they do is that they perform the same function.
The carburettor helps in sending the right volume of fuel needed in the combustion chamber.
The EFI also performes this role too but in an electronic way.
When the carburettor is faulty, it will reduce the volume of fuel that is being sent to the combustion chamber.
This will starve the combustion chamber of fuel.
Due to this, efficient combustion will not be possible.
This will lead to a reduction in power being produced from the combustion chamber.
When this occurs, it can be due to some reasons like the float needle being stuck in a closed position.
When the float needle is stucked in the close position, it will restrict the volume of fuel that comes into the carburettor.
When there is less volume of fuel inside the carburettor, it will also limit the volume of fuel that is sent into the combustion chamber.
Solution
a)Free Stuck Float Needle
When your Mercury outboard motor Carburetor is malfunctioning, you have to troubleshoot.
Troubleshooting will help you discover the cause of the problem.
In the case of a Mercury outboard motor bogging when accelerating, a stuck float needle is usually one of the reasons.
To correct this, the float needle has to be free.
b) Purchase a New Carburettor
Mercury outboard motors bog on acceleration when the carburettor is bad.
Rebuilding a carburettor is always better if the level of damage is very minor.
This is because it is always less expensive when compared to getting a new carburettor.
But this will not be possible for the mercury outboard motor to achieve good efficiency if the carburettor is really damaged or in a critical condition.
Due to this, you have to make sure that you get a new replacement.
This will ensure an improved and better performance when using your mercury outboard motor again.
3) Bad Ignition System
Another reason why mercury outboard bogs when accelerating is when the ignition system is bad.
The components that make up an ignition system in a mercury outboard motor are very important as far as the functionality of the outboard motor is concerned.
Some of the ignition system components include a spark plug, spark plug cable, ignition coil and CDI system.
These systems work together to produce an efficient spark that helps ignite fuel mixture in the combustion chamber.
If any of them gets faulty, then the level of efficient ignition in the combustion chamber will be reduced.
This will lead to less power generation from the outboard motor.
When this occurs, it will affect the performance of the mercury outboard motor especially when it is accelerating.
In such a situation, what you will observe or experience is that the mercury outboard motor on your boat will bog, vibrate or shut down totally when the ignition system is bad.
Solution
a)Replace Faulty Ignition System Component
When you discover that there is any component of the ignition system in your mercury outboard motor that is faulty, you have to make sure that you replace it.
This can be a faulty ignition coil, a faulty spark plug or even a faulty plug cap.
When you discover a flaw in any of them, you have to make sure that you change them to a good one.
This will help in improving the efficiency of ignition in the combustion chamber.
As a result of this, you will experience a better and increased power production from your mercury outboard motor.
4) Faulty Fuel Filter
Mercury outboard bogs on throttling can be caused by a bad fuel filter.
Using a fuel filter in your mercury outboard motor is very important.
This helps in keeping contaminants and debris away from your combustion chamber.
But sometimes this fuel filter may stop working.
One of the reasons that can lead to this is when it is clogged with debris.
when a fuel filter is clogged with debris, it will reduce the free flow of fuel.
This will also stop the carburettor or EFI from receiving the optimum volume of fuel.
When this occurs, it will affect the power being produced from the engine of the outboard motor.
As a result of this, the mercury outboard motor’s performance will suffer.
This will show up in situations in which the outboard motor vibrates, bogs or even shuts down totally while being used.
Solution
a)Change Fuel Filter
The fuel filter in a mercury outboard motor is one of the cheapest parts.
But irrespective of how small and cheap they are, they play a very big role in the performance of the outboard motor.
That is why you must not joke with them anytime they are faulty.
If you observe that the fuel filter in your mercury outboard motor is faulty, you should change it to a good one that is new.
This will help increase the performance of your outboard motor when you are using it and avoid situations like shutting down while using your outboard motor.
5) Overloading
One of the bad habits that some boat operators still show is in overloading the boat.
Every boat has a particular load it can comfortably carry.
This also applies to the outboard motor that is used.
When a boat is overloaded, the performance of the outboard motor will suffer.
This will really show up when you are throttling the outboard motor.
If the boat is overloaded, you will experience poor performance when accelerating.
This will strain the outboard motor and will reduce the service life of the mercury outboard motor.
Solution
a)Load Boat According To Manufacturer’s Specifications
When loading a boat, you have to follow the instructions of the manufacturer.
This is by looking at the capacity plate of the boat.
This will help show the maximum load the boat can carry.
In the case of a mercury outboard motor, you should also load the boat according to the limits of load specified by the mercury outboard motor manufacturer.
This will help achieve a good performance from your mercury outboard motor.
Apart from having a good performance, your mercury outboard motor will last longer when it is not overloaded.
This is due to the less strain the mercury outboard will enjoy when it is not overloaded.
6) Overheating
Overheating is a silent killer when it comes to the longevity of an outboard motor and causes mercury outboard bogs when throttling.
Apart from destroying the longevity of the outboard motor, overheating leads to power loss in an outboard motor.
This power loss will lead to poor performance of the outboard motor.
When the mercury outboard motor is overheating, it will not be able to perform well when accelerating.
This will cause it to bog.
If the temperature is too high, the mercury outboard motor will shut down totally.
One of the primary reasons why the Mercury outboard overheats is due to poor or faulty cooling system.
This can be that the impeller or other components like the water hose is faulty.
When any of the cooling system components is faulty, overheating will occur.
Solution
a)Fix Faulty Cooling System
Overheating occurs when the components that are designed to regulate the mercury outboard motor temperature develops a fault.
This can be the impeller or the water hose.
Apart from the impeller and the water hose having issues, the water inlet can be clogged by seaweed.
That is why a detailed troubleshooting is always required.
This helps in knowing the exact problem.
With that, it will be easy to provide the best solution.
b) Maintain Good Oil Level
When overheating occurs in a mercury outboard motor, the common thing a lot of technicians check first is the cooling system.
This can be the impeller and other components like the hose.
Another place to troubleshoot when there is an overheating in a mercury outboard motor is the oil level especially if it is a four stroke outboard motor.
The oil has a seperate compartment in a 4 stroke mercury outboard motor.
The oil helps in lubricating the moving parts in the outboard motor engine.
It also helps in regulating the temperature in the engine too.
That is why it has to be at the correct level.
You can check the oil level with the help of the oil dip stick.
If you discover that it is low or due for change, make sure that you change it.
7) Faulty Fuel Pump
The fuel pump helps in releasing fuel for use from the fuel tank.
For this to be effective and efficient, the fuel pump has to pump out fuel at a regulated pressure.
This will ensure that the carburetor is not getting too much fuel than it can efficiently function with.
A functional fuel pump will also not produce less volume of fuel that can cause fuel starvation in the combustion chamber.
If the fuel pump is faulty, then situations like mercury outboard motor vibrations, bogging and stalling will occur.
Solution
a)Replace Faulty Fuel Pump
If you discover that the fuel pump used in your Mercury outboard motor is faulty, you have to replace it.
When replacing it, you have to follow the right precautions.
Make sure that you do not replace it with a fuel pump with a smaller or larger capacity.
This will lead to continuous issues when you use your mercury outboard motor.
To avoid this, you have to make sure that you replace a faulty fuel pump with the same capacity specified by the manufacturer.
This will help achieve an efficient and continuous performance from your outboard motor.
8) Low Cylinder Compression
For your mercury outboard motor to function well, it has to maintain a good compression.
This can be checked by performing a compression test.
If a Mercury outboard motor has a poor compression, it will affect the performance of the outboard motor.
This will easily cause flaws like bogging when accelerating due to loss of compression and power.
Some of the reasons this occurs is due to bad piston rings, bad engine block, etc.
Solution
a)Rebuild Engine
When you discover that you are having a poor compression in your Mercury outboard cylinder, you have to fix it.
This can be done by performing a troubleshoot.
By troubleshooting, the exact cause of the low compression will be discovered.
It can be that the piston rings are bad.
Whatever the cause may be, make sure that it is fixed.
This will help the mercury outboard motor to achieve a good compression in the cylinders.
As a result of this, the performance of the outboard motor will improve.
With this, mercury outboard bogs on acceleration will stop when the compression in the engine cylinder is good.
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