Small Diesel engine inverter generator

Hi everyone , all this talk and interest in inverter generators of late had reminded me that 6 years ago i bought a 5KW inverter generator that looks the exact same as my petrol ones except that it has a diesel engine , when bought the person who sold it me said it would want a tune up , once home trying to run it was too painful it was noisy but the main fault was it smoked so bad real horrible black smoke .
Not being too smart on diesel engines i did the most common fault finding first , i cleaned out the air filter , and fuel filter still the same , so i bought a new injector to eliminate that , still the same , so it went in the too hard to bother with basket , thinking well the electronics are the same so if i ever need spare inverter or whatever i at least have them .

So as i said all this talk reminded me i need to try again on the diesel generator as i have now managed to get a supply of clean veggie oil that i am using on my tractor and will use on a diesel heater this coming winter i thought it would be good to try it out on the generator as well if i could work out why it smokes so bad .

After a couple of days messing with the engine i managed to get it running fast enough without too much smoke once up too correct speed most of the black smoke went away ,
but the second i hit the eco button and it slowed down the smoke came back with vengeance , leading me to think that the problem all along might be tied in with a fuel guvnor or what ever it is that meters the fuel on these Chinese single cylinder engines ,does anyone have any idea’s how these things work ?


Yes, probably governor related, i don’t know how it works on these engines, but it sounds like the trouble.
Does it miss? (Hunting governor)
Hard to start?
Whiteish smoke use to be late injection.
You should probably have some kind of setting screw for the amount of fuel injected, (this could be a matter of a 1/10 of a turn) if this has shaken loose, or someone have tampered with it?
Diesels use to have warranty/emissions seal on all setting screws (i don’t know if chinese use that?)


I have taken the time today to find out as much as i can about these small Diesel engines ,seems they are mostly clones of the Yanmar L100 10HP engine , so have been watching many people play with them on YouTube , seems that maybe leaving out a shim or adding a shim beneath the pump itself is how they adjust the amount or the timing of the fuel delivery .
Yes Goran the naughty person that sold me this unit had been messing with it ( it needs a tune up ) was his words to me . but on closer inspection i can see and tell he had stripped this generator apart as there are parts missing from the cowling that can only be removed if the electronics are removed first( not a small job to do ) , i am just hoping he did not strip the engine and got the timing marks wrong , the engine does sort of run but blows out a LOT of black smoke .
Tomorrow i will remove the injection pump and swap it with a working one from another engine i have and also be able to check the shims on both machines then and will let you know what i find out , as this is all very new to me .


Adjusting these with shims can be a pain, i would probably ad a thin shim and test, if it still smokes, ad one more, and so on, probably needs some special equipment to do it the right way.
When using shims there are often no “standard” setting, needs to be set for every individual engine.


I looked around some on the net, seems this engine has kind of built-in governor, you need to check so it’s not stuck, also the sleeve on the injection pump needs to turn freely, and there shold be some kind of linkage between injection pump and governor that may come loose.


You can easily overdose a diesel engine with the amount of fuel per working stroke, and this is what happens here, if the engine smokes black, it is necessary to set the maximum amount of fuel limit.
A synchronous generator with a rectifier is installed here, similar to an alternator in a car, the rotor magnetization regulator takes care of maintaining the desired voltage, but the voltage depends on the speed of rotation and the strength of the magnetic field. When the engine is operating in “eco” mode, the rotor is magnetized very strongly and a large torque is required for this, so the diesel fuel regulator opens it to max and black smoke is emitted if it is not set correctly. This “eco” mode is actually not so “eco”, since the efficiency of the generator deteriorates significantly when we strongly magnetize the rotor, as well as the thermal effect of the diesel engine drops when it works at max, I recommend that you slightly increase the “eco” revolutions and limit the diesel fuel set correctly.


I know this may interrupt your real mechanical needs at this time Dave. But Tone has touched on a logic train that Matt Ryder has ran into also.

The conclusion of this string of logic is you may not want to run this system on Reduced RPM “Eco”.
MattR’s reasoning now to not want a reduced RPM Eco has to do with the thermal nature of using an on-demand charcoal made fuel gas.
Your’s will be the nature that a combustion ignition engine needs hot cylinder walls, piston crown, valve faces, and in-cylinder head combustion chamber for ionizing heat ignition and best burn it’s long chained fuels completely well.
A spark ignited engine will have a wider internal temperature tolerance for completed, clean combustion especially on a gaseous fuel from high loadings to, low loadings. But even they will fall down let go too cool as evidenced in the failures to three major auto manufacturers running deactivation of some cylinders. They still cylinder walls oil; with no burning off of that then, excessive oil. Thermal stable expansions are lost. Those deactivated cylinders then wearing then like an always kept too cold engine.

Liquid wastes fuels and raw vegetable fueled engines needing to be kept highest internal temperatures of all.

Think. An Internal Combustion engine at Idle has no load external loading. Does no measurable work. Like a gas burner pilot light always minutely consuming to be always ready go quicker-better to loaded working.
On the other hand going from a complete cold state not consuming; to a hot stabilized able to work state takes time to warm up to good thermal stable operation.
Which wastes more fuel? It depends. How long in Idle-mode. How much energy expending time to come up to stable operation.

Realize ECO is not Idle. It is loaded running. Just the needed working loading is much less than that engines/heat systems 75%-85% of maximum.
Maximum system loading is not per-say all of that fuel use efficient either. A lot of heat not being converted to actual work accomplished.

So Dave it is very possible you may want to skip on your diesel engine inverter-generator ECO running. Use it for loaded bulk battery bank recharging. Use it for clothes washing day high energy needs. Whole family holiday dinner cooking. If you house AC; in the heat of the day.
At low electrical needs times like battery bank floating/final percentage topping . . . mid-day low activity times then PV solar would shine (yes an intended pun).
Or use a smaller gaseous fueled inverter-generator instead.
The very effective using a small APU unit in ships, airplanes, railway locomotives and now big over-the-roads trucks.
As lower mass air cooled, less fuel is used to get up to operating temperatures. Later shut down; as less mass, then less energy lost bleeding down to ambient.

Big hammer. Medium hammer. Small hammer. Teeny, tiny hammer. They all have their best-use purposes.
Hint. With only once choice better to be one size up too big, choking down in low energy needs times.
This WILL warm up your hand and arm holding it back. The “efficiency” is quicker getting the needed job done with the tool on-hand. And moving on.

Your diesel engined systems greatest advantage is that it can use a relatively heavy oil fuel. That is the prize. Never lose sight of the prize idealizing a process.
Steve unruh


Thanks for all the comments on this problem , i spent a lot of time watching video’s on these engines and feel like i understand them a little tiny bit better than when i pulled it out the other day .
When i get home from the men’s shed later this afternoon i shall be pulling the injector and swapping it with a good working engine and also injector pump . least that way i can eliminate 2 items straight away .
I have taken on board what you said Tone and it makes perfect sense along with Steve and Gorans comments it has started sinking in better , I don’t need to run in eco mode at all it was a typical silly thing for me to do because for 5 mins it had run with little smoke and for a second i had thought i had fixed the problem till i hit that switch and then the smoke screen appeared and the engine died , so wont be doing that again .
Thanks all


Up date 3rd day on still no joy , swapped over injector pump and injector from a spare running engine i have and still the same so fingers crossed the guy i bought this off 6 years ago didn’t tear it apart for some reason only to put it back together with the timing marks out a tooth , although saying that maybe its electronic as it had started to run fine till i hit the eco button , think i am going to have a rest and come back to it with a fresh outlook and start from the beginning again ,maybe wait another 5 years even . lol


“The leading culprits behind black smoke can include faulty injectors, a malfunctioning injector pump, a clogged air filter (leading to insufficient oxygen supply), a problematic EGR valve (contributing to valve blockage)”

I bet it is a plugged egr valve since everything else was most likely checked. :slight_smile:

The other thing is there might be some sort of temperature sensor that gets it out of ‘startup’ mode that might be faulty. In startup mode, it would be dumping fuel in to get started then back off once the engine is warmed up.


Hi Sean , i am not a diesel person and have had very limited hands on experience , but as far as i can tell there is no egr, its a clone yanmar single cylinder looks pretty basic as you can get as far as small engines go , i also had the electronics side disconnected, just in case it was trying to overload the engine and it has the same symptoms .
I downloaded the Yanmar L100 manual last night and going through it has highlighted maybe 1 other thing i have not yet checked and that is valve clearance’s , so if i get a chance to take the cover off later today i will make sure they are within the clearance’s if they are then i shall leave it for a few weeks and have a break and move on to breaking some other machines i have laying around .
Cheers Dave


Me either. :slight_smile:

If this is the same manual, I am not seeing an eco mode or an egr valve.


I once bought a 10hp 2 cyl. OMC (1950? Johnson) outboard motor from a friend. He had worked on it for a while, then gave up. I thought I was a gift to the world of mechanical stuff (I was about 15 years old), so I proceeded to work on it. I couldn’t find anything obvious, and I tried and tried. Many parts later, many questions asked of marine mechanics, Many looks at dealer repair manuals on microfilm, (way before home computers) I could not get it to run. the only symptom was it flooded a lot. Finally, looking at an expanded view of the carburetor, there was this little thick fiber washer spacer, that I didn’t remember being in the carb float bowl center mount. I found something that fit, and it started up and ran like a champ after that. So, don’t give up on it yet, look closely at those expanded parts views!! :thinking: :cowboy_hat_face:


Hi all , this engine is a clone of a Yanmar L series motor ,and Sean that is the Manual i also downloaded , the inverter has a ECO mode on the electronics that activate a stepper motor that in turn adjust the throttle position , i am at a point now where it will not run at all unless i put the run lever right the way over ( as in full throttle ) and then it does run sorta very rough and coffs and splutters to a stop .
Mike I am not giving up on this just yet i am taking a break away from it while i gather my thoughts , but i will check valve clearance and remove the inverter electronics again so it just becomes a diesel engine that way i know the generator is playing no part in its rough and problematic running .
Thanks Dave


Got it. :slight_smile: It is similar to the harbor freight I looked at earlier I think in Matt’s thread.

I would check to see if the stepper motor is in the ‘correct’ place or whether it is turning. It might not be smart enough to correct itself if it is out of position. And you can check to see how it is turning without it being installed. And make sure the connector on it was put on the correct way. Maybe it is turning backwards. so instead of opening all the way, it is actually closing. If there is linkage, it could also be in that as well.

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Hi Sean , i looked at the throttle plate and the position of the spring after reading the manual last week and it seemed fine and in the 50Hz holes , the stepper motor was disconnected after me hitting the eco button and is not affecting anything at the moment , iI cant wait to get back into it as its bugging the hell out of me now .