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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14439
Experience:  Certified on Onan and Generac generators
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I have a EB3500 honda portable generator. Its started having

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I have a EB3500 honda portable generator. Its started having power surges. the lights get really bright for 30 to 60 seconds and goes back to normal. The engine does NOT increase RPMs. RPMs stay the same at all times. Can someone help on this problem?

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What is the serial number of your genset?


Customer: replied 5 years ago.
The serial number of my genset is EA6-3008852. EB3500X


I needed this, as there are 4 different schematics for the EB3500, and they are serial number dependent.


This is a fairly basic set as far as generators go, and there are not many parts that can go bad.


What I need you to do is to connect a voltmeter to the receptacle and monitor the voltage while the set is running.

With a light load on the set, if the voltage is fluctuating more than about 5 volts, but the engine is not changing speed, it would indicate that the AVR is going bad.


If the voltage fluctuation is not more than 5V, it may indicate a possible issue in the stator, but this is highly unlikely. Let me know if this is the case.


Customer: replied 5 years ago.
My genset has been running for about 10 mins. At start up the voltage was reading 169 to172 volts at the recepticle. After about 10 mins RPMs increased very very slightly and voltage dropped to 118 to 120 volts. After about 30 mins the voltage jumped back up to 169 to 172 with RPMs dropping ever so slightly. And after about 5 to 10 mins the voltage will drop back to 118 to 120.

That voltage is way too high.


I am very concerned about the fact that the voltage drops when the engine speeds up and rises when the engine slows down - this is just the opposite of what should happen.


This is still most likely a bad AVR, but right now what really needs to be done is to measure the output frequency to verify engine speed.

If the engine is not running at the proper speed, it will not do much good to test anything else.


Do you have, or have access to, a frequency meter?


If the engine speed is what it should be, the AVR needs to be replaced.

If the engine speed is not what it should be, this needs to be taken care of first.


Customer: replied 5 years ago.

I don't have a frequency meter. The genset has been running for more than an hour now. the voltage has been staying at 118 to 120. It did that 168 to 172 volts for about 2 mins. But the RPMs did drop ever so, so slightly. It is so slight that you can just bearing hear the difference. I am some what mechanicaly enclined. Maybe the average person may not hear the difference. But the voltage dropped back to 118 to 120. It may do this voltage thing in a 4 to 6 hr. time frame about 3 to 4 times. Where is the AVR on the genset?

The 118-120 range is perfectly normal - in fact, maybe just a sliver low if there is no load on the set.


The AVR is located under the end cover of the genset.

It is a kidney shaped device with 6 wires going to it.


Customer: replied 5 years ago.
Grey colored, looks like a almost half moon, with 3 wires together with a plug at the end. The other 3 wires are independent with single connectors at the end?

That's it - the Automatic Voltage Regulator.


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