# EU3000is surging.



## cmartyn

*HONDA EU3000is surging.*

Yet another EU3000is surging thread Yay!

I bought this baby 11 years ago. When I first got it, it stumbled when not in eco mode but I never had to run it out of eco mode so paid no attention. It has about 700 hours on it now. In the last big storm a couple of years ago it would not start my fridge in Eco mode like it used to, I had to keep eco mode off. So, last fall, it was really running like crap and I decided to try and fix it. I just threw a new carb on it and that improved it a lot but it would still not run my fridge in ECO mode and it still stumbled. So I took it all apart and bought a new head and valves for it. I also put a new coil on it as well now it starts good and will run my fridge in ECO mode again but it still stumbles around when eco is turned off. It is very annoying. I took the carb apart and cleaned it. Replaced the O ring on the pilot, cleaned it with Honda's wires, same result. The carb is pristine, all gaskets are new. I cleaned the fuel tank with acetone and replaced the filter in the bottom of the tank, petcock is clean and fuel flow is fine. I see a lot of this on the web, even people demonstrating a new one they just bought. Why do they do this? BrrrrrrWrrrrrrrr... Very annoying. I ordered a new pilot screw and will try adjusting it rather than leaving it one turn out. Its a fuel screw right? Not an air screw. I also bought a 78 main jet but I have no hopes for that. 

Could this be some sort of early inverter bug? The TCM just constantly moves the throttle around trying to keep it running.

Also, I did not replace the valve cover. Do these have any bits inside that can fail? I am going to disconnect the breather hose and see if that helps but was wondering if a new valve cover would help?

And The spark plug indicates lean and yes, it smoothest out with the choke on about 1/4.


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## cmartyn

*RE HONDA EU3000is*

It won't let me edit my post yet so I wanted to add something.

Here is a video I took of it running.

Also, air filter is new and the prefilter is oiled with NoToil.

HONDA EU 3000IS Running

0:00 Engine has been running for 10 minutes with Eco Off
0.12 Eco is engaged
0.31 Eco off
0.37 Load Applied (1250 Watts)
0.50 Eco Engaged while loaded
1.03 Eco still engaged load removed
1.08 Eco off
1.30 Shut down


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## RonJ

Just out of curiosity, are you running ethanol-free gas, and have you ever used SeaFoam in the gas?


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## cmartyn

Hi, thanks for the response.

Our state does not allow ethanol-free gas so yes, I am using 10% ethanol gas from Shell which gives me the best car mileage. I tried their 87 and 89 octanes which work fine in my two lawnmowers and snowblower. 

The snowblower I have has the same carb and engine. (gx200) and the last time I mucked with that carb on that snowblower I had to chip the crud out of the bowl with a screwdriver but it never warbled like this. 

This is a new carb, new fuel line, gas tank cleaned with acetone, new fuel filters, new gaskets, new insulator, new head, new valves, new valve sprins, seals, retainers, and a new spark plug and fresh gas. 

I don't think this is a fuel quality issue. It appears to be more of a design flaw. On a regular mechanical governed engine, the governor continuously adjusts the throttle to maintain RPM. The electronic throttle seems to use the same principle but the way the software appears to be working is to throw the throttle on and back it off rapidly. Its not a smooth operation. There is a tiny damper spring that seems to want to compensate for this but it isn't enough and it seems to accentuate any issue. The only way to fix it would be to have a perfectly tuned engine which is almost impossible with a non adjustable carb.

Here is a video of a fairly new generator doing it. The guy is blaming cold weather but I have seen these up in Alaska with a foot of snow on them run better than this. When I shot my video it was 40 degrees.






And the guy did an earlier review of it in the summer and it was doing the same thing!






And here is a brand new one, with Eco off.. whirr.. Whirrr Whirrr.. very annoying if it can be fixed.


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## cmartyn

You asked about Seafoam, I did add it to the gas after the first 15 minutes of running and after an hour, I shut it down and pulled the carb, I replaced the pilot, and the same result.


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## exmar

Not going into design flaws or electronic throttles. After 50+years of working on engines I can state that have never seen the issues that are now routine since ethanol came into the picture. I've read that ethanol is added to the tanker trucks at the refinery as a last step before being dispatched as it almost immediately starts finding water and separating it. What I've learned to do with all my small engines is add StaBil (pick your own there's a ton of them out there) to an empty gas can so I'm sure that when filled, it's protected. Seafoam isn't an immediate "fix," over time running, it dissolves or removes crud. Don't be selfish with the SeaFoam if you can't smell it in the exhaust you didn't put in enough. That's for cleaning, just adding periodically is a different story. JMHO


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## cmartyn

I have the original valves soaking in seafoam right now. Seems like a good solvent. The head wasn't too bad. A stiff brush and a little carb cleaner and now I have a spare for the next time. Or next owner. I have been eyeing that eu 7000i with fuel injection. EFI and an inverter seems like a good match on paper at least. I want to look at the wiring diagram and parts price list before I take the plunge.

Design flaw was probably too strong of a term. But, it would not take much for Honda to externalize the circuit board for throttle control. It doesn't belong buried inside a 500.00 part. And adjustable gain on the governor would cost nothing. Without a proper engine control module implementing an electronic governor requires an adjustable gain to make up for differing conditions unless there is some automagic adjusting going on. The inverters have gone through a couple of revisions but I don't know why.


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## cmartyn

@exmat, I agree. Ethanol gums up quick. For my 2 strokes I buy the Stihl gas in the little cans. But these bigger engines need too much fuel and the airport won't sell gas to consumers. A friend of mine is a member at the local marina and he claims non ethanol gas was eliminated as an option in 1995. They retrofitted a lot of engines back then and have a good business cleaning fuel systems every spring. But this thing is clean and I am sure Honda took ethanol gas into account when they designed it.


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## thehandyman1957

I have had this happen a lot, and my fix was to put a better stronger spring for the damper spring. This usually always settles the surging issue. But the real teller here is that the plug is showing lean and the 1/4 turn out for the choke smooths this.

Your gen is starving for gas or has a air leak somewhere. If you concentrate on those two things then you should be fine.

There is only so many things that can cause this.

It would be interesting if you could get your hands on a small amount of Ethanol free gas just to see what it would do though.


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## cmartyn

The spring is so tiny. How could I put a stronger spring in there? It is like the size of a pen spring but not as long.I will take a look through the spring bin and see if anything feels stiffer. Not the easiest experiment in the world.


No chance of getting gas without ethanol here. They have octane boosters for old cars, that's about it. There are some racing fuel suppliers and airports that have it. A few places claim to have it for 10.00 a gallon on their truck. No easy consistent supply. Again, its a GX200, nothing special, all my Hondas run fine enough, this is under scrutiny because it is so quiet, it just sounds like it is running strangely at idle which is kind of annoying. Lots of folks seem to have this issue.


I have checked / rechecked, and checked again, it doesn't appear to be a component or assembly issue. Everything is pristine and it sort of runs like new, which is crappy. I notice as it gets warmer outside, it runs better. It also seems to run slightly better when it is level vs on a slight incline.


I am going to tune the carb a bit which I guess is frowned upon but if it helps, it seems like the right thing to do. When this is running it spends 80% of its time at idle or under a slight load. When it is under load it does not stumble as much, the more load, the smoother it runs.


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## thehandyman1957

Sorry, I misunderstood what spring you were speaking of. For that one I usually will cut it in half and re shape it to hold.
This will give the extra holding power. If you can, find one from another gen or a hardware store so you can go back to your old one if it does not fix the issue. 

Have you taken a can of ether and sprayed around the carb area? This will tell you if you have a air leak anywhere as the engine will rev if it sucks up the ether (starting fluid).


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## cmartyn

I did try with the ether and couldn't get a conclusive result because of the cabinet design, it is difficult to tell since there is so much airflow in through the door when you open it, everything just blows around too much. Nothing jumped out at me. I was very careful installing it. I have since probably over tightened it a bit. Honda used a gasket sealant when they put it together. If not a sealant, some sort of adhesive at two points. I feel that the sealant between the choke plate and gasket and between the insulator (carb side) and gasket might have just been done for quick assembly. Those gaskets are very narrow in spots. I didn't use any goop when I put it together. I have some fuel lube which works on aircraft engine fuel line threads. When I put my experimental carb on, I will use a little of it on those gaskets just to make sure there is no leak. I hate removing that insulator because it takes 1/2 hour to make sure it is on right with that foam surround and grabbing the spark plug wire etc.


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## cmartyn

Well, I mucked with it some more, opening the pilot 1/2 turn had no effect and changing the jet up one size to a 78 did nothing so its emulsion tube soldering time I guess. Probably a little weekend engineering going on at Honda with this thing.


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## thehandyman1957

Wow partner, I feel for ya. Hope you find it.


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## cmartyn

I am concentrating on why one carburetor works better than the other now. They are both recent carbs, less than a year old. Very strange. The only thing different is the idle setting. I'm not sure if it is even relevant with this throttle mechanism though. The service manual makes no reference to it. I measured 4 1/2 turns when I took it apart and that's what I set it to when I put it back together however it is set visibly lower than the other new one I have.


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## thehandyman1957

Perhaps different machining?


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## cmartyn

Threads may engage slightly differently I guess. The body is the same for sure. Has the same casting numbers et all. I guess I should measure the idle. Whatever it is. It runs at 2450 / 3550 eco / normal or something like that.


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## Tom Burns

TruSouth TruFuel 4-Cycle Ethanol-Free Fuel-6527206 - The Home Depot


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## dkemppai

cmartyn said:


> *HONDA EU3000is surging.*
> ...
> Yet another EU3000is surging thread Yay!
> ...
> Could this be some sort of early inverter bug? The TCM just constantly moves the throttle around trying to keep it running.
> 
> Also, I did not replace the valve cover. Do these have any bits inside that can fail? I am going to disconnect the breather hose and see if that helps but was wondering if a new valve cover would help?
> 
> And The spark plug indicates lean and yes, it smoothest out with the choke on about 1/4.


So, I realize this is an old thread. However, Fighting a very similar issue. I though this may help someone else in the future. 

After doing all of the standard fuel, spark, carb cleaning issues my EU3000is was still surging. Pulled the carb for about the 4th time and pulled the little servo motor off the carb. The gear train felt a little stiff in that motor. Seemed to me that the weak little butterfly spring wouldn't be able to keep the backlash pushed to one side of the gears

So, I took a pair of pliers and bent the tiny tabs back on the motor housing, and added just a few drops of some very pure 10W oil. Worked it back and forth a few times, seemed better. Squeezed the tabs back, and bolted it back on. I also plugged/unplugged a throttle cable on both ends a few times to clean the contacts. Ran great after that. Better than it has in a long time. 

I think what was going on, was the grease was stiff. The throttle butterfly couldn't keep the backlash of the gears in check. This backlash was causing the throttle to constantly try to seek the correct position. First overshooting, then undershooting, forever...

Anyway. Hopefully this may help someone else out some time. 

Dan


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## iowagold

dkemppai said:


> So, I realize this is an old thread. However, Fighting a very similar issue. I though this may help someone else in the future.
> 
> After doing all of the standard fuel, spark, carb cleaning issues my EU3000is was still surging. Pulled the carb for about the 4th time and pulled the little servo motor off the carb. The gear train felt a little stiff in that motor. Seemed to me that the weak little butterfly spring wouldn't be able to keep the backlash pushed to one side of the gears
> 
> So, I took a pair of pliers and bent the tiny tabs back on the motor housing, and added just a few drops of some very pure 10W oil. Worked it back and forth a few times, seemed better. Squeezed the tabs back, and bolted it back on. I also plugged/unplugged a throttle cable on both ends a few times to clean the contacts. Ran great after that. Better than it has in a long time.
> 
> I think what was going on, was the grease was stiff. The throttle butterfly couldn't keep the backlash of the gears in check. This backlash was causing the throttle to constantly try to seek the correct position. First overshooting, then undershooting, forever...
> 
> Anyway. Hopefully this may help someone else out some time.
> 
> Dan


silicone dielectric grease or spray works better


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