Which would be generic voltage regulator compatible with the generator?

Most of the time it is the AVR that has blown. Check out our videos on how to test them.
We hold your AVR in stock and have a whole Help Center dedicated to helping people fix their Portable Generators. Check it out on our site. https://www.generatorguru.com/

Parts Spares for Generators and Small Engine Machinery

Usually generators that have stood for a very long time loose the magnetism in the ignitor coil magnet. With care, if you can find the low voltage wire into the generator 'motor' you can apply a 9v battery briefly to it and spark it into life. Use the generator if you get it generating, for a good period and don't leave it unused for a long while.
*IF YOU DONT KNOW AND UNDERSTAND ELECTRICITY DO NOT TRY THIS. GENERATORS CAN KILL*

Assuming the generator circuit breaker is on, depending on the model it could be the voltage regulator or the slip ring brushes or both. If it's a portable it could be a capacitor problem.

https://www.partstree.com/parts/generac-power/portable-generators/0045822-generac-guardian-15-000-watt-portable-generator-sn-4

Found this wiring diagram. see if this will help you.

is engine running at 3600 to 3700 rpm at full load. most small engines run at this speed.you can buy a small tach on ebay TINY TACH.. you have to know what the engine speed is

Hello, it sounds like either you have a voltage regulator failure, the rotating field coil is shorted or opened, or the exciter windings have failed. No easy answer because there are a number of issues here as you can see. Depending on how old the unit is you might have warranty. I would suggest you take it to a generac service center to have it checked out. I have 30 years experience with generac units. If it is a voltage regulator issue, (this can be expensive) you can get a jobber regulator. This link is for a good generic substitute. http://www.mcphersoncontrols.com/html/mcp_products/voltage_regulators/MTS63-4.html
I have used this regulator on 4000 watt to 50 kw units successfully. If it is a winding, then to rewind the stator part of the generator is expensive and a new generator is cheaper.
joe

Hi Jake and welcome to FixYa. I am Kelly. Check both CB1 and CB 2 circuit breakers by pushing them to OFF and then back ON. Open the brush block access and then start the unit. You should read voltage at the brushes of 5 - 14 VDC on the terminals of the brushes. If you do not have 5 - 14 VDC at the brushes the probable suspect is the automatic voltage regulator (AVR). If you do have the correct voltages then with the unit OFF.... do a resistance check across the armature coil by reading resistance at the brush block terminals. You should read around 180 Ohms. It can be more or less resistance but for sure less than 500 Ohms. If you do NOT get a resistance reading remove the brush block assy and test the armature directly by reading across BOTH slip rings. You should get the resistance previously stated. If you have resistance then most likely there is a problem with the brushes. (Too short / broken carbon brush / missing spring or a defective terminal.) Without knowing the AVR output voltage and the armature resistance reading at this point it is difficult as to how to advise you to proceed. Let me know the values you obtain for AVR DC voltage at the brushes and actual ARMATURE resistance reading. Make sure you use R x 1000 on the meter. I am having thoughts of maybe a broken wire somewhere inside the control panel also.

Thanks for choosing FixYa,
Kelly

Check the automatic voltage regulator .Or if you have a bad neutral connection one leg will be very high and one leg low causing damage to sensitive equiptment.

Pull the no 1 and no 4 wires off the voltage regulator and apply 12 vdc from the battery to them + to no 4 - to no 1. start unit and see if its putting out at least 60 VAC. If it is then you have a bad voltage regulator. If itis not then you have to investigate the brushes, stator, and rotor.

the instructions says the voltage regulator is automatic/digital. when you check the voltage is there any load on the generator? if applying load to the generator doesn't help, you can manually change the motor speed where the governor connects to the carborator, but it may change the frequency, but the regulator may fix it