Hello. I finally have time to tinker with all the gens I bought. So the 831A runs nice and holds load up to about 2kw. At 2kw it acts like my 803 at 10kw. It holds it and smokes just a tiny bit. When I add say 500 watts it starts smoking pretty good and doesn't like it. If I try 3kw black smoke and stall. Kind of like if I try to run my 803 at 12kw then try to jump to 15. I'm not doing these things to my gen but the smoke and struggling remind me of that kind of overloading. I'm under rated load though. I've read about people getting these 831 gens to like 3700 watts. The TM doesn't address this issue directly. It mentions injectors and injector pump timinga bit for similar issues. I'm just wondering if anyone has had a similar problem with these and what was the fix? BTW I have it running outside right now with no load and it is not exactly perfectly smooth. Not sure how to describe it little bumps in road I guess. I did buy and install the circuit board from kloppk btw. Also I've heard check the return line. I pulled it off the injector and blew through it and it was clear but the routing seems funny pre injector pump the fuel line tees with the after injector do it seems there would be back pressure from the fuel pump. Are the fuel lines correct. On the diagram something called the orifice which could be my tee seem to be about right with the drawing. This is why I like having more than one and one of them working correctly. Something to reference. Thank you for any help.
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Mep 831A load issues
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This is a video of me loading it to 3kw. At 3kw she blows black smoke and dies.
For a little more description. When I got it the reason it wouldn't run is a rat called it home and had chewed the wire to the fuel pump. I cleaned all the rats nest and fixed the wire and am now trying to get it running perfect. I feel lucky I got one with a working inverter.
I thought I might have found something. When I checked the valve clearance it seemed pretty off one pretty tight and the other loose but it's doing the same thing with the adjustment. I think I'm going to have to just go through the fuel system one thing at a time until I figure it out. I wonder if the fuel timing is off? It shows 21 hours on the meter. Maybe I'll get lucky and one of you guys will have a good direction to go.
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did you add the fan load of the load bank to your load amount?
2Pbfeet
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So, yes, that's more smoke than I would like at the loads you are adding. When you add loads, I can hear the engine respond, and it sounds to me as if it is keeping the rpm's up. The cutout out 3,000W looks from a distance more as if the overload protection kicks in. Are you getting any warning lights?
That seems like a lot of carbon on the exhaust for 21hrs, at least in my experience. These engines generally don't smoke until well into the high/over load region, at which point the safety controls should have kicked in. Generally, these engines aren't fussy, and take a lot of abuse in other applications with no issues.
Besides cleaning the rat's nest out, and adjusting the valve clearance(s), what else have you done? Did you check the tappet on the valve with loose clearance? Sometimes folks set the valve clearances too tight and then the tappet buckles- these are pretty soft.
Are you 100% sure that the engine is fully primed, especially the high pressure line and that the injection pump doesn't have an air leak from the fuel supply? If there is any doubt, I would bypass all of the fuel lines to the injection pump, and suction directly from a clean container to see if that helps the engine. I think that if I were to be critical of one thing on this setup it would be the waste diesel/suction fuel line design, as it often seems to leak air.
If you haven't done it already, I'd start by checking the air intake (rat's nest #2?), air filter, checking for foreign material in the preheaters, and then checking the oil (level, color/viscosity, and me personally, changing the oil), and then pulling the injector to check the spray pattern. If that gets you nothing, I would think about pulling both tappets, and checking them, and then pulling the muffler. If none of that surfaces anything of note, I would double check your prime in the high pressure line, and for an air leak into the fuel line. I would fill the fuel filter with straight SeaFoam, and run it for two minutes and let it sit for a day or two, run it again for two minutes and let it sit for a day or two.
Variations on this engine run for months straight at close to full loads in isolated telecom repeaters. (Extra deep oil pan and an oil filter)
All the best,
2PbFeet
That seems like a lot of carbon on the exhaust for 21hrs, at least in my experience. These engines generally don't smoke until well into the high/over load region, at which point the safety controls should have kicked in. Generally, these engines aren't fussy, and take a lot of abuse in other applications with no issues.
Besides cleaning the rat's nest out, and adjusting the valve clearance(s), what else have you done? Did you check the tappet on the valve with loose clearance? Sometimes folks set the valve clearances too tight and then the tappet buckles- these are pretty soft.
Are you 100% sure that the engine is fully primed, especially the high pressure line and that the injection pump doesn't have an air leak from the fuel supply? If there is any doubt, I would bypass all of the fuel lines to the injection pump, and suction directly from a clean container to see if that helps the engine. I think that if I were to be critical of one thing on this setup it would be the waste diesel/suction fuel line design, as it often seems to leak air.
If you haven't done it already, I'd start by checking the air intake (rat's nest #2?), air filter, checking for foreign material in the preheaters, and then checking the oil (level, color/viscosity, and me personally, changing the oil), and then pulling the injector to check the spray pattern. If that gets you nothing, I would think about pulling both tappets, and checking them, and then pulling the muffler. If none of that surfaces anything of note, I would double check your prime in the high pressure line, and for an air leak into the fuel line. I would fill the fuel filter with straight SeaFoam, and run it for two minutes and let it sit for a day or two, run it again for two minutes and let it sit for a day or two.
Variations on this engine run for months straight at close to full loads in isolated telecom repeaters. (Extra deep oil pan and an oil filter)
All the best,
2PbFeet
I didn't add the fan load specifically but the amps the load bank says it's drawing match my clamp meter to the 10th of an amp so the load bank automatically adds the fan load or it's so small as to not matter. Thanks for the suggestion though. I've a couple times forgotten to use the 1.732 when calculating load and not figuring out why things weren't matching up until I remembered three phase is different math.
Thank you for the suggestions. I will work on the things you mentioned. So the injection pump only has one shim. Is that normal? Seems like you might want more adjustability. I did look inside the air intake and it all looks new and shiny in there. I do seem to get a bit of debris flying out of the exhaust so I wonder what that might mean. I'll keep digging and updating
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I didn't get far nought into the engine yet to check the tappet under the push rods. Do i pretty much need to remove the engine from the housing do do all these checks or can it be done installed? When I checked the valve clearance I did it with the pull cord and several times around and my best guess on tdc. Not ideal I know but I've been hoping I might find the trouble without needing to dig into the engine. I need a shop. Working out in the dirt is less than ideal but it's what I've got right now. I did check the rocker arm assembly and it's id and od stuff. Checking the simple stuff first and it's what the TM suggests for black smoke. Everything was fine with those dimensions. I pulled out the injection pump and did that inspection and everything looked good except only one shim. I was thinking I would try checking the injection timing. Is there a way to do that with the motor in the housing? I can't cheat that. I'll look at it tomorrow and figure that out. The fuel lines look pretty old and stiff so maybe I need to just replace them all. I haven't found in the TM the size fuel lines. They look bigger than 1/4".
I've basically just got started.
2Pbfeet
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I hear you on field work and in shop work.
If you have cruddy hose, by all means replace it. My experience is that the one thing these engines are quite sensitive to is a little air in the fuel lines.
When you had the injection pump out, was the the pin in the fork? (Visible through the access plate above) Nothing mushed, bent, or not engaged?
My bad, I meant push rods above, not tappets. Push rods are pretty easy, just pull the rocker arm assembly off. You can pretty easily check for length and straightness on a flat surface.
TDC can be gotten a couple of ways, but for the valve lash adjustment, I just use the pull cord, knowing that during the intake stroke, especially toward the end, the valves are closed.
The injection timing is pretty stable in these machines as a rule. That's why they do so well in the back of beyond. It wouldn't be my first place to look for the problem that you are having. Unless something is very worn, whatever there is probably right.
If the air filter is ok (intact, and clean), then given debris flying out of the exhaust, yes, I'd think about pulling the exhaust, and having a look see.
All the best,
2PbFeet
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Thank you for clarifying. I did pull out the push rods and they looked good. I didn't roll them on a flat surface. I'll keep digging in the directions you mentioned instead of breaking the engine apart for now. Thanks again
Well i figured out the debris. Just a lot of sticks and twigs,leaves ect down by the exhaust and close enough to get burnt then fly out. Back in the actual exhaust in not sure how anything could get in there. I dug far enough to see bank in there. I replaced the fuel lines from the fuel pump to the filter and filter to injection pump. Not the return lines. I drained and changed the oil and added 4oz of sticktion. I changed the fuel filter and filled it with sea foam. I have been cutting zip ties and inspecting and repairing wires that need it. That rat chewed on a few. I could see a wire chewed and touching ground somewhere acting like load to the pmg or something drawing load that can't be seen. I think unlikely but not impossible. I did run it once today sometime between all these things and put it on 3kw load and it held for idk 30 seconds or so before it started acting like it was going to stall out and I lowered the load. At 2 or 2.5 kw if will mostly hold the load pretty good at 2.75 kw I ran it until it stalled and when it did I didn't get any warning lights. I think it might be better now than yesterday? Not sure. The first time I put sea foam i only had enough for say half the filter. I pulled the filter off again when I found my other can and filled it up ran it for two minutes and now it's off. I did pull the injector and it was sootie but looked to be undamaged I guess. I cleaned it reinstalled it and torqued it down and ran it and it is the same. I'm not going to run it any more today. I am going to continue to check wires ect. Oh I did try to stick my bore scope camera down into the cylinder while I had the injector out but it wouldn't fit in the hole i think the spacer or gasket was in the way and the TM says to discard the gasket if you pull it out and I don't have one so I didn't.
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2Pbfeet
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That seems like progress in a number of areas!
The rewiring looks nice. Rodents can do amazing amounts of damage in such a short period of time. I would recommend screens to exclude rodents, and mud daubers if this isn't stored somewhere mouse and insect proof.
When you get the time and materials, I do recommend replacing the return line, as that double "T" area just before the injection pump seems to have caused a number of folks grief over the years due to small air leaks.
Yes, getting a borescope into these requires a thinner than typical borescope. BTW: These engines have a copper crush washer at the head. It often doesn't come out when the injector is pulled, and I have seen any number of these engines that had multiple washers down there. Not a recipe for success from what I have seen.
Did you check the spray pattern of the injector when it was off?
That's a fair amount of carbon in the oil for 21 hours, but I don't see any metal shavings, which is great. The water came from the water bottle, right? Did you clean the mesh oil filter?
The photos are quite helpful, thanks!
All the best, 2PbFeet
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I do keep it in a conex that has good seals but I definitely will rodent proof it if and when it's susceptible to them. I already killed the first set of batteries I bought it by keeping it in the Dark so long. Since it has the solar battery keeper might as well utilize it. I didn't check the spray pattern. I was thinking about that when I had it out. I guess you just turn it upside down and reattach the fuel line then crank the engine with it pointing up? I didn't clean the filter yet either but I didn't put the oil i want to use yet either. And wanted to try running it after I cleaned the injector. I probably should have. I know you guys are awesome at spotting things when helping people and pictures speak volumes. I'm not sure 21 hours is real. A lot of paint chips are coming off the engine ( silver ) I'm guessing that's the rebuild paint? It doesn't have a rebuild tag but who knows. Yes I had just emptied the water bottle to catch the oil. I need to make a hose that threads into that spot the plug is in. The oil looked sootie but felt slippery enough and I didn't notice any metal either. I'm pooring it on my trailer boards too hopefully protect the wood a little. I'll order the return fuel lines so I can change them. I should order some 3/8 line too since the little piece between the tee and the injector pump is 3/8 barbs.
Thank you again for the help.
Thank you again for the help.
I just realized I even took a picture of my thoughts on how to check the spray pattern. Is that how? Like ice got it?
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Here I think is proof and hopefully a clue for someone more knowledgeable than me about these fuel systems. I had bought some 3/16 fuel line down at the auto parts store hoping to temp in and test while I wait for the right stuff. Well the hose was loose on the little plastic tee and my clamps weren't the right size either. I put the gen in run and had leaks.
Any way one thing that confuses me about this return fuel system is the double tee and the fact that it is always putting positive pressure on the return side of the injector. If someone can explain this to me and how it's supposed to work i would love that. I will research and try to learn myself if not. The needing a path for return fuel i get but that part not so much.
Any way I thought if I send the fuel back to tank from the first tee between the two pums and then run another line to tank from post injector for any needing to go there too. I know it's not right and the people that design these things know what the are doing and I'm just not fully understanding yet. But in this configuration the gen held 3kw it wasn't running right exactly but it didn't bogg down and die.
I took this video and tried to show what I did and what the governor was doing also. I had lost that little tee but I've found it now but I think i will order one or two anyway.
If this helps someone know what's going on with the gen that would be awesome. Right now I plan on ordering the right fuel line and clamps and keep digging
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I did make one troubleshooting mistake when making this new video. It might be that sitting with sea foam made the difference and not the return line changes. I didn't try it before to know for sure. I wasn't planning on running it i was just trying to put new lines and when that wasn't working I got side tracked lol. Any way it was nice to see it take the load even if it wasn't right just to see that I will get there was good.
2Pbfeet
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To answer the injector test question, yes, that's sort of how to do it on the machine, but I would do something so you aren't spraying diesel into the muffler insulation. Just sayin... Personally, I like to have the injector clear of the engine, but rags or pig blankets work, too. I've seen others modify a clear plastic jar to accept the injector, and capture the diesel.- YouTube
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Here I think is proof and hopefully a clue for someone more knowledgeable than me about these fuel systems. I had bought some 3/16 fuel line down at the auto parts store hoping to temp in and test while I wait for the right stuff. Well the hose was loose on the little plastic tee and my clamps weren't the right size either. I put the gen in run and had leaks.
Any way one thing that confuses me about this return fuel system is the double tee and the fact that it is always putting positive pressure on the return side of the injector. If someone can explain this to me and how it's supposed to work i would love that. I will research and try to learn myself if not. The needing a path for return fuel i get but that part not so much.
Any way I thought if I send the fuel back to tank from the first tee between the two pums and then run another line to tank from post injector for any needing to go there too. I know it's not right and the people that design these things know what the are doing and I'm just not fully understanding yet. But in this configuration the gen held 3kw it wasn't running right exactly but it didn't bogg down and die.
I took this video and tried to show what I did and what the governor was doing also. I had lost that little tee but I've found it now but I think i will order one or two anyway.
If this helps someone know what's going on with the gen that would be awesome. Right now I plan on ordering the right fuel line and clamps and keep digging
View attachment 951788
On some diesel engines, the injectors will pass significant quantities of diesel, sometimes because they use the pressure in the diesel to further increase the pressure in the spray. This engine passes very little diesel beyond the injector ("the return" side, though strictly speaking it is really leakage). Since that "return" line is basically injector lubrication bypass weep, I am of the opinion that a few psi of back pressure is basically round off error at the injector.
You would need to ask someone more experienced with the history of this generator why the fuel lines were plumbed the way they were. (@Guyfang- any thoughts?) All I can come up with is that someone was trying to avoid a fuel tank penetration.
Yes, SeaFoam might have helped. If I were a betting man, I'd bet that the fuel line was leaking a little air, and perhaps still is leaking a little bit of air. I've seen so many of these units have that issue. In my experience, Yanmars just don't run well if there is even the tiniest bit of air getting into the injection pump, or in the high pressure line. On the MEP-831A, if the fuel line is good and the fittings are clean and tight, it does work as designed. A more typical Yanmar motor design runs that injector weep line all the way back to the fuel tank, so an air leak on the line is not an issue and uses fewer in line fittings.
All the best,
2PbFeet
Sorry I know i jump around a lot. I try not to. One more thing. I never saw any fue