Odd Onan issue

[rcpd34]

I have an Onan 5500 that has always started easily and run fine. Has about 240 hrs. I have a guy doing some inside work today so I showed him how to start it and turn the heat on as it was cold. He called me and said the generator would only run for about 2 mins then stop. Never had this issue before, so I went over and started it, turned on an electric space heater and let it run about 30 mins. Ran fine. Thinking he was nuts, I unplugged the heater, getting ready to shut it down and the generator quit shortly after the load was removed. Gas tank full with good gas treated with Seafoam. Oil level good. Serviced not to long ago. Anyone have any thoughts?

[bkirkpatrick]

carb.

[rcpd34]

Ok; I finally got out there today first nice day off. Dumped 4 cans of Seafoam in and started it. Ran for 10 sec and stopped would not restart. Code was 36; fuel. I saw the factory fuel filter was still there and remembered that Onan recommends it be replaced with a pass through. I had one on on hand from my prior camper so I swapped it out. Cranked it with the supply hose off and I have fuel. Put it back together and started it. Started up and ran for about 30 mins under various loads. Runs perfect. Removed the load entirely and it dies within 30 sec. Checked the code and it's 14 this time; Overfrequency fault. (Engine governor unable to maintain rated freqency. Corrective actio: take to dealer. Any ideas?

[allcool]

I speak from experience,,,Best thing to do is start from the beginning...

Check fault codes before doing anything else. Find out what fault code shuts it down.Your owners manual details how to check fault codes. Do it exactly as it says.

Sometimes it is hard to determine what the fault code actually means in real world troubleshooting.
With the vast knowledge here on our forum, one of use should be able to determine whats up from the fault code. Or at least a logical step by step process of elimination.

[mrxlh]

If you have a multimeter that is capable of reading hertz and recording min/max hook it up and watch what it does when the genet shuts down. That will tell you if it is a gov setting. as they have a min and max Hz shutdown.

[Dirtclods]

Love Seafoam any updates on your carb?

[64thunderbolt]

fly-boy wrote:
My money is on the carb- I suggest you buy a new carb and just switch it out- the carb is not that expensive and it is really easy to replace. You could try cleaning it but I have had mixed results-

The fact the gennie is running under a load with no problem almost guarantees you it is the carb- there is a 0.9% chance it is something else. 🙂

carb for y 4K is $285 not cheap keep looking.

[bkirkpatrick]

The governor adjustment would be the last thing on the list (although very good to know). Check carb, fuel pump, fuel filters, add Sea Foam, etc. Mine was the fuel pump. But yours seems to be a pattern when not under a load.

[Strabo]

I am a firm believer:

Genny, Use it or Loose it!!!! We average 30 hours on our Onan 4000 Every trip.

[broccoli2]

Or read this
fixed my onan

[broccoli2]

check ground wire on new battery

[big_buford]

Other thread Here

[rcpd34]

lumpy790 wrote:
instead of replacing the carb ..... go to a auto parts store and pick up a couple bottles of Sea Foam and dump them in the tank and let the gen run for 10-15 min alternating on and off load (draws the fuel through different circuits) then let it set for 30 minutes (cleaning) and repeat procedure a few times.

When I bought my TH it had been sitting for 2 years and Sea foam cleaned the carb out. Somehow it still ran with the old bad gas that was in the tank with a little fresh dumped in.

Great idea! See the post above yours. lol. Great minds think alike!

[lumpy790]

instead of replacing the carb ..... go to a auto parts store and pick up a couple bottles of Sea Foam and dump them in the tank and let the gen run for 10-15 min alternating on and off load (draws the fuel through different circuits) then let it set for 30 minutes (cleaning) and repeat procedure a few times.

When I bought my TH it had been sitting for 2 years and Sea foam cleaned the carb out. Somehow it still ran with the old bad gas that was in the tank with a little fresh dumped in.

[rcpd34]

Ran it again today for 20 mins with load; no issues. Removed load and it died again, gonna check for that wire this weekend. Also bought 4 cans of Seafoam; gonna dump it all in and let it run a while and hope it may clean a dirty jet. Will also search for that post. Thanks all!

[Macman83]

I wish I could remember where I saw it, but there was a post about the same sort of thing with the Onan generator. I turned out to be a wire was rubbing against the govornor arm, or the throttle linkage. When the gen was loaded, the arm was in a different position, and so the wire was not touching, but when the gen was unloaded, the arm contacted the wire, and it actually messed with the voltage that the generator was producing. It sensed an over/under voltage, and shut the unit down. Might check it out, as it could take many hours for the linkage to rub through the wire insulation. Search for generator issues on this forum, as I think it was here that I read it. (don't have time to search for it right now)