There are a lot of reasons why yamaha outboard keeps stalling when used.
But most of the times when this occur, it is usually an issue related to fuel.
It can be due to reasons like usage of bad fuel or less volume of fuel supply in the combustion chamber.
Apart from fuel, it can also be caused by other reasons too.
Stalling in an outboard can be caused by bad fuel, bad carburetor, overloading, bad cylinder condition, low fuel supply and also bad spark plug.
Why Yamaha Outboard Motor Keeps Stalling
1)Stuck Carburetor Float
For your outboard motor to perform well, the combustion chamber has to be well fed with fuel.
The volume of fuel released into the combustion chamber has to be of the right volume.
To make this possible, the carburetor helps in this function.
The carburetor times the release of fuel with the help of components like the float needle.
The float needle helps fill the carburetor bowl with fuel when fuel volume is low in the carburetor bowl.
When the fuel in the carburetor bowl is less, the float needle will come down.
This will open the fuel inlet for fuel to enter the carburetor before being sent to the combustion chamber.
While working, the float needle can be stuck.
It can be stuck in an open position which will lead to the release of excess fuel.
It can also be stuck in the closed position too.
When the float needle stucks in the closed position, no fuel will enter the carburetor and combustion chamber.
This will starve the combustion chamber of fuel.
As a result of this, the outboard motor will stall.
2) Outboard Overload
Every outboard motor has an optimum weight it can comfortably carry.
The bigger the capacity of an outboard motor, the heavier the weight it can comfortably carry.
But to know of the precise weight your outboard can comfortably, you have to check in the manufacturers manual.
If you load your boat with a weight higher than the capacity of the outboard motor, your outboard motor will be over stressed.
Due to this, you will experience issues like vibrations when accelerating.
At a worse case scenario, your outboard motor will stall while in use when you overload it.
This is one of the reasons why a yamaha outboard motor keeps stalling when being used.
To avoid this, you have to make sure that you do not overload your outboard motor.
3) Overheating In Outboard
Overheating is one of the reasons why outboard motors get easily damaged.
This can be caused by a lot of reasons.
But one of the major reasons why an outboard motor overheats is faulty cooling syatem.
When the cooling syatem of an outboard motor is damaged, it will not be able to reduce the heat generated in the outboard motor.
This can be caused by a faulty impeller or a clogged water hose.
Due to this, the outboard motor will begin to rise in temperature.
To avoid severe damage from this, modern outboard motors have an overheat sensor.
This helps in shutting down the outboard motor when it exceeds the tolerable temperature limit.
Due to this, the outboard motor will be shutdown by the overheat sensor when the temperature is too high.
This will cause the outboard motor to stall.
4) Use Of Bad Fuel
For your outboard motor to perform well, you have to be mindful of the quality of fuel you make use of.
If you use a good fuel, you will enjoy a good performance.
But if you use a bad fuel, then you will have a poor performance when using your outboard motor.
This can be due to dissolved particles in the fuel which will end up clogging the carburetor.
A bad fuel also contains water.
When a fuel with water enters the combustion chamber, it will not allow combustion to take place well.
Due to this, the outboard motor will stall.
5) Bad Spark Plug
In the functionality of an outboard motor, the spark plug plays a very vital role.
The spark plug helps in igniting the fuel in the combustion chamber of an outboard motor.
Through this, power is released from the outboard motor.
But if the spark plug is bad, there will be a poor level of combustion in the combustion chamber.
This will result in low performance from the cylinder that has the bad spark plug.
As a result of this, the overall performance of the outboard motor will be reduced.
This will lead to issues like having an outboard that stalls or vibrates when accelerating.
6) Bad Stator/Alternator
The spark plug ignites fuel in the combustion chamber to produce power.
But before this power is produced through combustion, an electric charge has to be produced.
This occurs in an electric starter outboard motor and a pull start outboard motor.
This electric charge is generated by the stator or alternator.
After that, the rectifier converts the alternating current from the stator or alternator into a direct current.
This is then used to power other electrical components in the outboard motor and boat.
This includes charging of the outboard motor battery and powering the ignition coil.
But if the stator is bad, then little or no electric charge will be produced.
If your outboard motor uses a battery, a bad stator or alternator will not charge the battery.
This will cause the battery to die quickly which can cause a stalling of the outboard motor especially when you want to restart after shutting down.
7) Clogged Outboard Carburetor
The carburetor helps in sending fuel from the fuel tank to the combustion chamber.
This fuel release is done in an orderly manner.
When the outboard motor is in an idle mode, the carburetor will release less fuel as the engine will not demand for much fuel.
But when the outboard motor is accelerating, the outboard motor will require more fuel in order to produce more power.
A carburetor that is functioning well will sense this and also realease fuel as needed by the combustion chamber.
But if the carburetor is clogged, this will not be possible.
A clogged carburetor will release less fuel lower than what the outboard motor demands.
Due to this, situations like vibrations and uneven acceleration will occur.
The engine will stall at some point if the volume of fuel released is too low.
8) Poor Air Mixture With Fuel
Another reason why a yamaha outboard motor stalls has to do with air mixture with fuel.
For combustion to take place well, the fuel in the combustion chamber has to contain some air.
This will help the spark plug to easily burn the fuel.
But if there is a poor supply of air, then you will experience some level of stalling when using your outboard motor.
9) Low Oil Level
For your outboard motor pistons to function well, oil has a role to play.
In a two stroke yamaha outboard motor, oil is mixed with the fuel.
But in a four stroke yamaha outboard motor, oil has a seperate section.
This oil helps in lubricating the piston in order to create an ease in the piston movement.
An oil in an outboard motor also helps in reducing the temperature of the outboard motor.
But if the oil pressure sensor detects that the oil in the outboard motor is too low, it will shutdown the outboard motor.
This is to help prevent damage to the pistons and other outboard motor parts due to a low oil level.
10) Poor Fuel To Oil Mix Ratio
In a four stroke outboard motor, oil has a seperate section.
But in a two stroke yamaha outboard motor, oil has to be mixed with fuel.
The outboard motor will perform well if you use the right mix ratio.
But if you use a wrong mix ratio, your outboard motor will perform poorly.
This is one of the reasons why yamaha outboard motor keeps stalling especially when it is a two stroke outboard motor.