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Honda EM5000SX generator - will not idle up when a load is placed on. Will produce power but will not idle up.

Need assistance in understanding if this is a common condition when the auto-throttle control unit is faulty. Unit runs at reduced RPM even when under load. Seems to run at full RPM when turngin auto-throttle off.

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  • Honda Master
  • 45,659 Answers

From your description and what you do , the problem is in the auto control unit
it will be in the system to reduce the rpm to idle when there is no load ( auto mains on off controller switching between genset and mains supply)
by turning the auto operation off you are committing the gen set to full rpms regardless of the power requirement
you have the option of having it fixed at an gen set repair shop or leaving it off and starting the genset only when you have a mains power outage
check with an electrician to ensure that it is possible to run it that way as if the mains power unit is not correct , when you start it and you still have mains power , it will destroy the gen set

Posted on Dec 13, 2016

Testimonial: "Thank you: To clarity some points: I do not plan to have the generator hooked up to my house (mains power). I plan to plug my freezer and fans into it when residential power goes out. This is mainly to keep the frozen items frozen. I am prepared to purchase and install a auto-throttle control unit if that is what is needed to get the unit to idle up when I (for example) plug a 500 watt light bulb into it. Currently the light will be dim unless I turn the Auto Throttle system off. When I turn the auto throttle system off the light get bright and the engine runs at full RPM. I would like a method to verify that the Auto-Throttle control unit is bad with with a DMM (or other simple tools). It is possible to test the Auto-Throttle unit in such a manner? thanks again."

  • Bill Boyd Dec 14, 2016

    if you want to use the generator properly then have an electrician wire up a 3 way switch into the power board and use a caravan connection
    run a lead from the gen set to that plug and move the switch from mains to off to gen set
    that way you have lights fridges fans freezers, tv running as normal and as it is a 5000 kw unit there will be plenty for continuous rated operation ( 4500 kw is max for continuous operation)
    turn off electric hot water as that will cause excessive current draw unless you turn off all other uses until the hot water is hot again and do any cooking on a gas top
    for your purpose , an auto controller is not necessary because when you want to use it you will have a need for full rpm and voltage out put from start
    the unit has to run at set rpms to maintain correct voltage and cycles
    you are testing the auto controller by simply plugging something into the outlet socket and it is not speeding up the rpms
    however it is best if the unit is tested by a gen set repair shop
    I am in an area where the mains power is generated some 2500 miles away so power outages are frequent and can last in excess of a week
    That is how I use my 5500kw unit and inconvenience is reduced to a minimum

  • Dave Dixon
    Dave Dixon Dec 14, 2016

    I ended up taking the front panel off the generator and moving the wires around in the Auto-Throttle unit. I took a voltage measurement at the two wire connection coming to the solenoid from the auto throttle unit. I was getting a good reading and it would change when I applied a load. This is key if you are working on this. Take this measure and watch the DC voltage when you add a load. I think voltage was about 20 volt DC no load and 0 volt DC under load. I might have those switched around but that's what I recall. When I noticed that change in voltage (load vs no load) I thought that the auto throttle unit must be working. I hadn't tested the solenoid with 12 volts so I did that. It didn't work with 12 volts from my battery charger (it may require more voltage). So, I figured I had a bad solenoid. I have conflicting results in regard to the solenoid. The unit ran at low rpm when I turned the auto throttle on but would not pull in with 12 volts. I felt that whatever the problem was might be fixed as I knew the solenoid would work based upon it running at low RPM in auto mode on prior tests. I put everything back together and it works now. :) I not sure what fixed it but maybe the position of the wires in the auto throttle unit or maybe a lose wiring connection. The service manual states that the direction of the wires matters going thought the auto throttle unit maybe the position of the wires also matters. In any event the generator now works and will idle up when I put a load on it (now).



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Posted on Jan 02, 2017

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SOURCE: on my EF30ISEH generator. cold,

Hi and welcome to FixYa, I am Kelly
First off I am just trying to help you and not participating on the FixYa site for the money. I have been working on small engines and generators since the late 1960's.

This is usually caused by the speed limiter assy. (Not a cheap part)
Item 22 this link:
The feedback wiper in the speed limiter is either dirty or worn. When you re-position the throttle arm the feedback wiper is making good contact again so it works normally. It appears that the feedback wiper in the speed control is not making good contact at full RPM so it does not drive the throttle linkage to idle.
If your careful dependng on the design of your speed control you just might be able to take the cover off and clean it up so the wiper makes contact. Wht ever you do DO NOT lift the wiper arm up. You will bend it and never be able to get it to function again. Just clean it. You can use sand paper but... be real careful.
If your speed control is 100 % electronic with only a small DC motor actuator you may have to see if you can clean the brushes and armature slip rings of the internal DC motor.
I have brought several speed controls back to life but it really is a major game of chance anytime you open one up. Just know that your stuck with a very expensive replacement cost for a speed control unit if you screw it up. ----
----It is not a bad thing to keep using your generator with a defective / improperly functioning speed control. As you know is just will not throttle down.
The part number listed above is for the original part number and has been superceded by another part number:
The ($60.00) service manual for this generator is available from Yamaha by PN: LIT-19616-CM-20
Anywhere else the manual is $80.00!

Thanks for choosing FixYa,

Posted on Feb 02, 2011

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