# Yamaha Generator EF1000 - Low Voltage



## kevin_1964 (Feb 14, 2006)

I adopted an old Yamaha EF1000 Generator that was not running.
I removed and cleaned out the Carburetor. Now the Generator runs but it is only putting out 40 volts.
Any suggestions on how to troubleshoot and fix will be greatly appreciated.
Thanks,
-Kevin


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## justin3 (Apr 10, 2007)

Are you sure the engine is operating at the correct rpms?


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## kevin_1964 (Feb 14, 2006)

*EV1000 - Low Voltage*

I do not have a tachometer.
Is there some way to check the RPM without a tach?
I will see if any of my friends or co-workers have a tach.
Looking at the carburetor and governor the throttle appears to be open full while the engine is running.
I was thinking with no load the governor should be closing the throttle to prevent the engine from running away???

Thanks,
-Kevin


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## paulr44 (Oct 14, 2008)

No real way to check RPM without a tachometer, but if you're meter can test frequency do that. Should be 58 to 62 hertz. If so, then it's running at proper speed.
The RPM of the rotor, and in turn the engine, determines the frequency. Most rotors are 2-pole, with the engine turning 3600 RPM (4-pole gensets turn 1800 RPM). Take the 3600 RPMinute, divide by 60 seconds PMinute, you get 60 hertz.
Better-made voltage regulators will try to make 2 volts per hertz, so you could have a regulator problem if the engine is turning 3600 RPM. Or, it could have dirty or bad brushes, or a shorted rotor or stator. Gotta check them RPMs first!!


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## Semiretired48 (Oct 11, 2008)

Here's another reason for low voltage.I had to replace the generator head on the APU on my Peterbilt many years ago when a bearing went out on the old head and took out the stator and rotor windings. Got a brand new one from Northern tool & installed it and everything was fine for about a month. Tried to run it while on a trip and noticed the microwave wouldn't function correctly, so I checked the voltage & found it low. Tried to adjust the voltage w/the throttle adjust, but the voltage kept dropping every time a load was applied. After investigating for about 15 min.,I finally found the problem. The rotor windings were loose on the shaft. So loose, in fact, that I could hold them still with a screwdriver through the cooling vents while the engine was running. Fortunately Northern Tool replaced the unit with no hassle an no additional cost to me.


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