I have this unit that the customer said some months ago it started conking out. So they lowered the power demand and it would keep running. Diagnosis today. It has low power. Checked all the usual things. Governor was set a little slow so increased it. Fuel filters replaced. Air filter replaced, it was filthy. Electric lift pump operation verified. IP fuel return checked during no load to full load, little difference from no load to full load. Removed shutdown solenoid in case it was not fully retracting, no change. No smoke at any time. Engine running seems normal. All these things were done one at a time to try to diagnose scientifically. Rated power 20.6 HP, that is 15.4 kw. Accounting for losses it ought to be able to do at least 12, but it is falling off much over 10 kw. It has the strange Yanmar sideways hybrid rotary pump. I think @thepumpguysc does not think much of them. I sure think it is low on fuel rate having eliminated everything else. It has 5000 hours and is relatively clean.
U r correct, I hate’m .. lol Right above the name plate STICKER.. is a 22mm(7/8”) bolt.. it’s actually an overflow valve.. check the spring, it might be broken.. then using a magnet, fish the piston out.. it may be partially stick in its bore.. Check theses 2 parts for rust.. that pump HATES WATER.. Lemme know what you find. DO NOT SPRAY THE PUMP DOWN WITH ANY CLEANER.!! If u do, you’ll watch ALL the pump numbers wash down the side of the pump.!!
OK, it's a long ways out there. So if the spring and plunger seem OK, then should I (carefully) just increase max rate until it seems more in line with the valve cover spec? Or would that be premature? Or remove the whole pump and send it in for calibration which would obviously be a shame for something that runs mostly perfectly? It says 15.4 kw on the sticker, I don't know if that is with or without the fan, or conversion loss on the gen head. The gen head is 12 kw max anyway, normally a 1.5 liter engine would pull this load easily and then some.
It’s all about making the customer happy.. If he says it’s low on power and you’ve checked all the usual suspects, put some fuel to it and see how it acts. Just don’t make it black smoke or you’ll be out there again for THAT.. Have u tested it WITHOUT the air cleaner.? I know u said u changed it, try running it without it.. Good luck
I'm just cautious because I wish I knew why it had lost power over the last 6 months, after having run fine for years. Only 5000 total hours, it's not worn out and it doesn't smoke at any time. You are probably the only person on the whole internet who understands what makes these things tick and offers advice. The rate adjustment is the only thing that makes sense, but why. Did the plunger and barrel wear, linkage wear, or accumulator problem as you suggest.
Compression falls off, valves need adjustment, plunger and barrels wear.. gear train back lash.. Let us know how it goes