Friday 22 August 2014

Yamaha YZF R125 fuel injection system



Yamaha YZF R125 clutch common problems rebuild strip inspection test and measure   





Fuel is delivered via fuel pump and pressure regulator through a fuel filter and into the fuel injector. The ECU uses the pick up coil / crank sensor to time the fuel injector to open and the other sensors are used with the ecu fuel map tp control the injector on duration. 

The injection duration uses a fuel map inside the ECU and inputs from the throttle position sensor, Intake air pressure and temp sensors , coolant temp sensor and even the lean sensor will cut off fuel if activated..


The fuel injection system on the YZF R125 is straight forward and easy to work on

it has inbuilt diagnostics and you can also use the Yamaha FI diagnostic tool for greater problem solving power.  

                             R125    FI wiring diagram 


R125 fuel pump wiring diagram 









Yamaha YZF R125  fuel injection system

you can test this by adding power to the terminals and listening to sound , or turn key and here pump prime , i like to test the fuel pressure too .

i use a home made tool to do this  

Yamaha YZF R125  fuel injection system



CDI obviously times the fuel injectors timing and opening duration 
these can go faulty but test all obvious first buy here on Ebay UK if needed 

Yamaha YZF R125  fuel injection system

Yamaha YZF R125  fuel injection system

Throttle body with other input sensors you test all these components 




Yamaha YZF R125  fuel injection system

Yamaha YZF R125  fuel injection system

Yamaha YZF R125  fuel injection system

Yamaha YZF R125  fuel injection system

Yamaha YZF R125  fuel injection system

Yamaha YZF R125  fuel injection system



Other posts of interest .

Yamaha YZF R125 testing injector


Yamaha YZF R125 , Yamaha FI diagnostics Tool Scanner Machine


 Testing and cleaning YZF R125 fuel injectors 





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