I have a yamaha 3000isb generator. checking

the generator consists of 2 120volt windings that run in parallel for 120 volts and in series for 240, check the change over switch make sure a wire hasn't fallen off, if you have a multi meter check both coils have the same resistance

On the bottom right side of the engine there's a throttle with a set screw. This set screw is a fine adjustment for voltage control. The lever should be pushed until the set screw makes contact with the stop plate. Using a voltage meter, adjust the set screw until you hit 110 volt and then lock the set screw. I just bought the same generator, it was putting out 85 volts. Witha phillips screwdriver a wrench and a multi meter, I had 110 volts in less than 2 minutes. It now operates flawlessly.

hi, what i need u to do for me in order to help u is, get a multi meter and tell me what is the voltage on the live and neutrueal.
should be about 60 volts. let me know.

Check the voltage with a meter in all the recepticles with your meter leads in the left and right slots on the plugs. Is that 184 volts AC there? If so, your gen has big problems with the voltage regulator. Let me know what you read. You can check the right slot of each plug to the round ground hole on the plug too, should be 120 volts there.


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Most generators use a flyball type governor within the engine to control rpm; also there is a voltage regulator that tries to maintain voltage at about 115v. The voltage regulator varies the voltage to the armature increasing /adjusting magnetic force. Use a meter with htz or freq setting to adjust engine governor to 60 cycles. When the generator is producing 60 cycles, the engine should be turning 3600 rpm, max power range. At 3600 rpm the voltage should be 115 to 120 volts. Loading the generator will cause governor to try to maintain 3600 rpm. Check engine manual for proper adjustment of gonvernor and linkage. The governor mech should last the life of the engine, however governor system does wear out. Expensive repair. enjoy