Hi all! I've lurked here for AGES to fix all my tech issues; you're all very helpful. I'm looking for some info about my
Onan Microlite 4KY Spec H generator.
The gist of my question is this: When it's running correctly, should I NEVER hear a surge and should my hz + volts be nearly perfectly stable?
The generator surged endlessly and did not run when I bought the RV. I have never heard an Onan generator running, so I have no idea if my interventions have made it "good as it'll get" or if I should still tinker with it.
Here's the history:
- Clogged carburetor from lack of prior owner use: Took it apart, cleaned it, took it to a small engine shop for an ultrasonic bath.
- Current gas tank: Regular gas, a can of Seafoam, and most of a can of Berrymans B12.
- Replaced carburetor gaskets, plastic float doohickey, float pin, float hinge. (Onan carb repair kit)
- Melted circuit board: Diagnosed at Onan shop; I put a new OEM part in.
- Bad fuel pump wiring/Prior owner had bypassed fuel pump/Fuel pump was trash: Long story short, I replaced the fuel pump with an aftermarket Airtex pump and wired + connected it correctly.
- Replaced fuel filter with very nice new inline filter before the pump.
- Replaced spark plug with new Champion plug. Correctly gapped.
- Changed oil.
- General wipe-down, inspection, WD-40 on the governor and choke moving parts.
- Most recently: Dialed in speed screw, governor sensitivity screw, and idle stop screw according to (edit: I can't put in links, but I used user hndymn's guide posted on this forum on a topic called "Onan generator frequency adjustment?" to adjust these settings).
My resources:- Local Onan shop is full of super friendly guys who seem to like me. I've ordered some parts from them. I'm already $600+ into the shop for the control board diagnostic and the control board itself; I'd rather not spend too much more cash. Plus, I like learning about my genny!
- Onan Master Service Manual, plus the service manual for my genset.
- All the correct tools and easy access to the generator.
- A Kill-A-Watt that I plug into an extension cord that is plugged into an interior outlet on my rig.
- An air conditioner that pulls about 2000W and a microwave that pulls about 1000W. (My "load bank"!)
Here's where we stand now:I'm getting consistent hertz readings between 61-63 at idle and 58-61 under 2000W load (call it half load, from the air conditioner). My voltage is generally between 110 and 130, up towards 127 at idle and down towards 118 under 2000W load. My voltage is never perfectly steady: When it's running at its best, it goes up and down a volt or two. The generator will run forever if I let it; it does not die. It no longer coughs or sputters. When I hold the throttle tang against the stop screw, I drop down to 54-56 hertz and it will stabilize at that speed (usually 54.7 or so) and will not die.
However, every minute or so under 2000W load it will slow down and then surge once; once in a while, it will hunt up and down for a few seconds. When idling (that is, with a nominal load, when the rig is plugged in but everything I can turn off is off), it will surge slowly but rhythmically.
I have been able to adjust it so it runs perfectly at idle, but when I do so, it's running at 66 hz. I can also adjust it so it runs a little better than previously described under 2000W load, but when I do THAT, it runs worse at idle.
When I load it suddenly to 2000W, it will hunt up and down about five times before it settles on the correct speed.
Is this pretty much
as good as I should expect it to get? Should I keep tinkering with the speed and governor sensitivity? Is there something I've missed?
Some final thoughts: - The only things I haven't done are replace the air filter and put a brand-new carburetor in it.
- My Spec H carb has a tamper-proof idle mixture screw. There is a vertically-mounted, very small screw directly below the throttle stop screw; I have not adjusted this screw, other than to remove it and clean it. There is an altitude adjustment, which I have at its lowest setting (I'm in Virginia), and directly below the altitude adjustment is a large screw that I think is the main carb adjust; I have removed that and cleaned it, and it is currently about as far in as it will go without putting a whole bunch of force on it.
I'd love to hear your expertise!
