Onan Generator Hunts Under Load
Hey folks! I wanted to first offer my thanks for those of you who answered my previous post. For those of you who don't know the backstory, I bought my first motorhome (2002 Fleetwood Tioga 24d) last month. As I am not very mechanically inclined, your help has been instrumental in my getting this far; when I brought it home, the generator would not start at all and you folks got me through that, so I thank you!
Here's where I'm at now, and it has a couple of us puzzled, so I figured I would reach out to you. I'll list all the known scenarios below. The generator is an Onan 4000 Microlite KY series.
- When I run the generator with no load, on first start-up, it runs well for 15 minutes or so. Voltage tests out within spec (127 +/- 4.5). After 15 minutes with no load, it starts to sag a bit (120-125 volts).
- The generator hunts with a heavy load on it (A/C or Microwave). This happens within 2 seconds of my turning either of those items on.
- If the generator starts to hunt, and I turn off the A/C or microwave, the generator continues to hunt -- it does not go back to normal no-load operation.
- If I turn the generator off and immediately back on, 7 times out of 10, it will come back to normal no-load operation. The other 3 times, it will continue to hunt.
- I ran Seafoam/Gas mix through the generator today to clean out all the valves, nooks, and crannies. While hooked up to the external can, the generator ran with no noticeable drops with no-load (I didn't try to put a load on it while running the cleaning). It was probably the best it ever sounded. When I hooked it up to main gas, it ran as above -- well for about 5 minutes and then I could hear the tone of the generator come down a bit.
Things I have done/tried (in this order):
- Filled the main gas tank with fresh gas.
- Checked the genset engine oil
- Replaced carburetor (got the generator running -- originally wouldn't start)
- Replaced fuel filter
- Replaced air filter
- Replaced spark plug
- Ran a hose to a can of Seafoam and gasoline to clean system
- Replaced fuel line from onboard gas tank to fuel filter
I also looked into the governor issue that many people have been talking about and downloaded the service manual to properly adjust it (within my limits -- I don't have a load bank to adequately test it). The issue is -- I can't get the generator to *not* hunt long enough to make adjustments to the sensitivity screw, and once it starts hunting, no manual adjustments bring it back to normal.
I'm stumped. Any help would be greatly appreciated. Thank you in advance! :)
Here's where I'm at now, and it has a couple of us puzzled, so I figured I would reach out to you. I'll list all the known scenarios below. The generator is an Onan 4000 Microlite KY series.
- When I run the generator with no load, on first start-up, it runs well for 15 minutes or so. Voltage tests out within spec (127 +/- 4.5). After 15 minutes with no load, it starts to sag a bit (120-125 volts).
- The generator hunts with a heavy load on it (A/C or Microwave). This happens within 2 seconds of my turning either of those items on.
- If the generator starts to hunt, and I turn off the A/C or microwave, the generator continues to hunt -- it does not go back to normal no-load operation.
- If I turn the generator off and immediately back on, 7 times out of 10, it will come back to normal no-load operation. The other 3 times, it will continue to hunt.
- I ran Seafoam/Gas mix through the generator today to clean out all the valves, nooks, and crannies. While hooked up to the external can, the generator ran with no noticeable drops with no-load (I didn't try to put a load on it while running the cleaning). It was probably the best it ever sounded. When I hooked it up to main gas, it ran as above -- well for about 5 minutes and then I could hear the tone of the generator come down a bit.
Things I have done/tried (in this order):
- Filled the main gas tank with fresh gas.
- Checked the genset engine oil
- Replaced carburetor (got the generator running -- originally wouldn't start)
- Replaced fuel filter
- Replaced air filter
- Replaced spark plug
- Ran a hose to a can of Seafoam and gasoline to clean system
- Replaced fuel line from onboard gas tank to fuel filter
I also looked into the governor issue that many people have been talking about and downloaded the service manual to properly adjust it (within my limits -- I don't have a load bank to adequately test it). The issue is -- I can't get the generator to *not* hunt long enough to make adjustments to the sensitivity screw, and once it starts hunting, no manual adjustments bring it back to normal.
I'm stumped. Any help would be greatly appreciated. Thank you in advance! :)
