the fuel injection system on the YZF R125 is straight forward and easy to work on
it have inbuilt diagnostics and you can also use the Yamaha FI diagnostic tool for greater
problem solving power .
See link here for more info on FI tool
the fuel pump
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
CDI oviously times the fuel injectors timing and opening duration
these can go faulty but test all obvious first buy here if needed
Throttle body with other input sensors you test all these components
Other posts of interest .
Yamaha YZF R125 testing injector
Yamaha YZF R125 , Yamaha FI diagnostics Tool Scanner Machine
see more Yamaha YZF R125 blog posts
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