Question about RTO New Yamaha Inverter Ef2400is / Yamaha Generator Ef2400 / Perfect For Camping, Emergency Home Use, Construction Sites And More!

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Rpm surge with intermediate power load

The generator ( yamaha ef2400is , new 10 hr use ) has a throttle surge (many times a minute) when under intermediate load >< 1000w .most annoying and dissapointing .

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  • ggsquiz Feb 14, 2009

    I have the same problem. I have had it back to the agent twice for inspections under load and they cannot find anything wrong. I pulled the side cover of and found the governor working overtime. The only time the gen set run good is under load, ie air conditioner etc.

  • corvette00 Apr 25, 2009

    I don't know if it is the same problem but it is similar. Mine I thought was related to the low oil shutdown system. The light flashes on intermittantly and at times quite often and even shutting down the unit at times. It has never been low on oil and overfilling it made no difference. However, if I tilt it by placing a 4x4 under one end or the other, it runs noticeably better. Is it the same solenoid problem or something else?

  • trederdb May 05, 2009

    My EF2400is has a throttle surge problem at idle. The more the load the better the throttle smooths to the point of no surge at all. It is worst when there is no load. I tried spraying the spindle of the solenoid with electrical cleaner as ggsquiz suggested but unfortunately there was no change to my problem - still there.

  • fishyme Dec 20, 2011

    Greetings from Alaska again.Using the tip from ggsquiz posted below I got some preformance.I have ordered and installed the part and now am working almost like it did when new 7 years and hunderds of hours of use ago.
    The part is called _____ motor unit assy _____7CF 81802 09 00
    It cost $73.00 from a Yamaha dealer only.
    Many may just need to clean theirs,simple things first.I run mine in temps from -35F to +80F for years.Mine was wore out,yours might get a little gummy if only used seasonal.SeaFoam your gas,clean your carb bowl,check your spark plug then as ggsquiz says clean your motor unit assy.I'm really really happy with my Yamaha.Good Luck



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The problem is the governor and is easily fixed. Do the following: Remove back and side panels to expose fuel tank. Insert screwdriver into fuel on/off switch on front panel and remove. Now remove top panel. To do this unscrew fuel cap, pull out fuel spill surround rubber and remove top panel, just pull gently. Now with fuel tank exposed, remove retaining bolts. Gently lift tank and rest on frame. No need to disconnect fuel line.On top of carby is the governor, protected in a black plastic shield. Unscrew the retaining screws that hold it to the carby. Remove electrical connection and then remove governor from carby. Now remove cover by pressing on the three retaining plastic clips and prize upwards. Now the solenoid is exposed. Remove solenoid from its base by unscrewing the two retaining screws. Now that the solenoid is fully exposed use an spray on electrical cleaner that can be used on circuit boards. Spray the base of the solenoid in particular the spindle. Whilst spraying the spindle rotate it a few times until it moves freely. Then replace everthing in reverse order. Where the spindle exits the solenoid dust particles collect and increase the friction between the two surfaces. If you do not want to proceed as outlined tell your dealer it is the solenoid and have it fixed under warranty.

Posted on Feb 14, 2009

  • fishyme Oct 26, 2011

    Greetings from Alaska,Great tip ggsquiz.I use my 2400is as my sole power out here in the woods where I live.After 7 years I don't know how many hunderds of hours I have now but it is just that.Regular oil changes,SeaFoam once in awhile and use that ground wire, but that solenoid trick got me back up and running.I started small and after a few light cleanings I got some progress.Ended up soaking the solenoid for a couple of hours in electrical cleaner then letting it drain for a couple of hours.I have improved from nothing to surging at low power but can get higher loads up and running now.Any tips where I can buy a new solenoild would help.As I said,I've hunderds of hours on mine so might be time to replace this part.


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Had the same problem on mine. Tried the Solenoid fix but didn't work. Took it to a lawn mower repair shop. They cleaned the carb for $55 and it runs perfect.

Posted on Dec 05, 2009

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Lubing the solenoid as outlined by ggsquiz solved the problem I posted on April 25, 2009. It runs really well now.

Posted on Aug 06, 2009

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Mine was doing the same thing and it turned out that one of the carb jets was slightly blocked. Once the carb was cleaned it ran great at low wattage but it exhibited the throttle surge problem at around 1500watts. The throttle motor assembly was diagnosed as being the cause. We'll see if that fixes this issue. Stay tuned

Posted on Aug 05, 2009

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