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Old 12-05-2012, 12:57 AM   #1
buickid OP
Lets ride!
Joined: Jul 2011
Location: Oahu, HI
Oddometer: 310
Yamaha Generator Troubles

Just picked up a EF2800i for really cheap today (damn you Craigslist, so addictive), guy said it had been sitting for a couple years and would only run with the choke on. Coming from motorcycles, I pinpointed this as a clogged carb from gas going bad. Guy used to use it to power his food truck, "everyday, for about 3 years". Whew, quite a few hours, but it didn't smoke when we started it up and compression seemed good on the pull starter. Gave him $180 for it and brought it home.

Spent a few hours dusting it off, cleaning out all the dust and cobwebs, adjusted the valves to spec, cleaned out the carb. Put it all back together and fired it up, still hunted without the choke, but held a load just fine (1000W halogen light). Decided to take the carb out and give it a little more cleaning action. The main jet was frozen in the carb and resisted all attempts of removal. Pretty sure its in the permanently now. Cleaned it out as best as possible with multiple passes of carb cleaner and compressed air. Runs pretty well now, only starts bogging at high RPM (manually controlling throttle), which I would expect to clear up as it runs with the Seafoam in the gas.

Although the motor purrs pretty good now, the inverter/throttle control side seems to be acting up (This unit uses an electronic governor, like the Hondas). Even though the RPMs are sufficiently high with no load, the AC pilot light will come on, and flicker a little, then stabilize. Once I plug a load in, the inverter will cut out, turning off the pilot light and the load. If I rev the motor manually, the inverter holds the load just fine. Also, with Eco on, the RPM gets really low and hunts. If it can hold RPM normally with Eco off, its getting plenty of fuel, so I'm guessing its flowing enough fuel.

I suspect there is something wrong with the engine speed control circuitry, but I'm not sure how to proceed. The only part I could economically replace is the stepper motor, about $30. The inverter board and engine control are a single, fully potted unit, about $600. Another symptom: a few times upon shut down, the throttle butterfly did not return to WOT as it should have, however it resumed normal operation after those isolated incidents. Anyone got some insight? If I can't get it to work, I'll probably part it out as any of the major replacement parts would cost far more than I paid for the unit.

Edit: I got the service manual and I'll check the resistance values on the stepper motor when I get the chance. I'm hoping its that!
2005 Yamaha Zuma YW50, 2009 Kawasaki Super Sherpa KL250
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