My ONAN 5500 finally fixed
As some might know, have been having problems with my Onan for years, ever since I got it. Started with checking fault codes, they translated to needing new carb, to get it running at all. Tried t...
Forum Discussion
dedmiston wrote:
I never knew there was an adjustment for the Hz. I adjust the carb for altitude, but I didn't know about the other adjustment. I wonder if this has anything to do with how mine runs rough.
Mine has a roll to it, like it wants to die. It starts fine and runs great under a load, but when it's just charging the batteries it surges and lulls. It never really quits, but it's annoying to listen to.
Could be an out of adjustment governor, or these things can cause your surge/roll/lull/hunting...
"binding governor linkage, fouled spark plugs, improper
valve lash, and dirty fuel filters". Most common imo, would be a gummed up carb...
Not sure of the hours, or state of tune on your gen-set, but if its not been done recently, couldn't hurt to do a 450 hour tune up, with all filters, valve adjustment and plugs. That would effectively rule out those as the possible cause.
If the 'roll' you are talking about is more like the gen-set hunting back and forth for the proper rpm, as opposed to a carb problem, not letting it run smoothly, might try an adjustment...? If its a carb problem, no adjustment will help. Been there done that.
As per the manual, try moving the spring that holds the governor arm a notch or 2(or more) away from the shaft end of the arm. Its a very easy adjustment you can always change it back no harm done(note which notch it was on to before adjustment)... worth a try.
If you can find a meter wouldn't be a bad idea to check hz droop. If the gen-set isn't running smoothly with no hunting then the hz will be changing up and down with the rpm, as will the voltage. But if your gen-set doesn't shut down, then hz are probably close to being in specs or the controller would shut it down.
It should run smooth, no roll, no hunting, no surging back and forth, at all.
page 8-20 onan manual...
"If droop is less than specified, or the genset
hunts, move the spring hook one or two
notches away from the governor shaft and recheck
frequency and droop. Repeat the procedure
as necessary.
5. The governor must not hunt. Check for hunting
under the following loading sequence:
A. No-Load • 3/4-Load • No-Load • 1/2-Load •
No-Load • 1/4-Load • No-Load."
