Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Hi guys. I have tried getting to the root of this problem via other forums without luck.  After doing some searching, I was able to track down this forum, it's great!  I have a problem with my Honda EX350 generator. Here's some information regarding this unit in case you haven't seen one before. It is powered by a small two stroke engine mixed at a 100:1 ratio. The carburetor is mounted to the bottom of the crankcase and uses a single metal reed valve. The igniton is a solid state design. Because the generator is of an inverter design (much like the newer Honda generators), the engine does not have to run at 3600 rpm. There is a low rpm position (150 watts) and a high rpm position (300 watts). Here is the problem.

When in the high rpm position under full load (300 watts), after almost exactly 2 minutes of running, the thing bogs down for about 6-7 seconds (just like you were putting the choke on), then goes back up to normal rpm. This goes on until it runs out of gas, like clockwork, every two minutes. I cannot figure out what is causing this. I have checked absolutely everything and have come up with nothing. I have a friend who owns the same unit, and after spending hours troubleshooting my generator and finding nothing, I was forced to simply change parts to see if I could find the problem. Here is what was changed.

air filter, carburetor, reed valve, spark plug, exhaust, gas cap (vented)

None of this fixed the problem. The thing is, the engine starts first pull every time and runs at a steady rpm.  The engine just seems to be loading up and just bogs down for a few seconds, then it seems to clear itself up.

Here's the thing, partially blocking the air intake with my thumb causes the engine to run the exact same way until I remove my thumb. But when the engine experiences the problem by itself, it only happens every two minutes.

Does anyone have any ideas what might be the problem, I am out of ideas.

Bill,
Never seen one. No idea what I am talking about. Never stopped me before.
I'll guess tank over carb, no pump. I would still go down the fuel restriction trail. Hose, tank, filter, shut off valve, elbow, nipple.

does this happen only with a connected load? or with no load attached & anytime the gen. is running?

Thanks for the replies guys.  It only happens when running on high with the rated load, 300 watts.  I tried it again tonight, and it runs perfectly for 2 minutes, then it's like someone blocks the air intake, or turns the choke on. (I know for a fact that neither of those things is happening) This lasts for 5 seconds, then it clears right up, and runs perfectly for another 2 minutes.  If I run the generator with no load, it runs fine.  If I run it on low with the rated load (150 watts), it runs fine.  If I run the generator on high with 200-250 watts, it runs fine.   Only when I run the generator on high with the rated load (300 watts), does it act up.  I'm wondering if maybe it might be something in the generator system that's causing the engine to cut out under the rated load.

Thats what i was wondering & why i asked how it ran with no load. What kind of load are you putting on it?  it sounds like perhaps there is too much load on the generator, and overdrawing it would lug it down and make it act as you've indicated. 300 watts (2.5 amps, or 5 - 60 watt light bulbs) is a pretty small generator and would overload easily.. and its possible the generator head on yours is putting out slightly less FLA  than its rated at. you said a friend had the same generator, you might try his under the exact load and see how it behaves.

What sort of load requirements do you have for a generator? it may be to your advantage to go to a larger one, keeping in mind, tool motors for ecample require more start up amps than load running amps.

Thanks again for your help.  This generator was basically built by Honda to run lights.  That's all I run with it.  The 300 watt load is a spotlight that I run for ice fishing.  I have run the same exact light on other EX350's with no problem at all.  I'm lost at this point and don't know what to do.  I think I'll try switching inverter units with my friend to see what happens.  Any more suggestions are welcome.

I've never seen this model generator, but I'll venture a guess that the fuel tank way not be venting properly. At lesser loads, it gets enough fuel to run ok, but at high load, not enough air is getting in the tank allowing a partial vacuum to develop and just as the motor is starving for fuel, what ever is blocking the air flow in loosens up and lets air in for another 2 minute run. A total guess on my part, but easy enough to check out by loosening the cap and see how it runs.

  BJ,

I think you are right on the money, cap not venting!!

                                                                        Fred 

My bet would be something wrong with the inverter when running at full load.  There could be a capacitor or something within the inverter to help out when running at full load that is not working properly and draws down every two minutes, overloading the engine.

thats my thoughts, that for some reason its overdrawing the generator head. perhaps the output of that particular generator was a bit low, but within tolerance when manufactured. too.

i really think if it was a fuel venting problem, eventually it would fuel starve even at the low 150 watt setting, but an easy way to check this would be run it with the cap loose and see if the problem clears up.

also, if a volt meter is available, check the output voltage on the unit when this problem occurs, if it is only a matter of overdrawing the gen. head there should be a noticble voltage drop.

Wow!  Thanks for the great replies guys.  I really appreciate your taking the time to help out a stranger.  I have switched gas caps with my friend's EX350, no change.  Just for kicks, I'll run my EX350 with no gas cap, and let you know what happens.  When the generator "loads up" for a few seconds, the rpm's go way down and the overload light comes on.  This is normal as the ouput of the generator is dependant on engine rpm.  Higher rpm = higher output and vice-versa.  The 300 watt bulb does not seem to dim when the generator loads up, indicating a satisfactory voltage level..  I'll try the removing the gas cap for now.  I'll get back to you guys tonight...