Generator Problem

[Hammerdown]

Our Onan 5500 runs fine under load, usually with roof A/C but when the A/C cycles off, the generator runs for about 10 seconds and shuts down. It will restart but won't keep running unless under the load of the roof A/C. Any suggestions on what to look for?
Thanks,
Dick

[pwf16129]

does it blow any black smoke when it shuts down? if not ch the low speed idle screw possibly backed out, sounds like running on high idle with load governor is keeping speed up or possibly low speed jet is dirty when unloads come back to idle is starving for fuel if black smoke possibly choke is sticking or needle has trash under it?

just my two cents worth good luck

[Hammerdown]

Thanks for the suggestions. I don't see any black smoke, it just stops running like I shut it off.

[dieselclacker]

Originally Posted by pwf16129

does it blow any black smoke when it shuts down? if not ch the low speed idle screw possibly backed out, sounds like running on high idle with load governor is keeping speed up or possibly low speed jet is dirty when unloads come back to idle is starving for fuel if black smoke possibly choke is sticking or needle has trash under it?

just my two cents worth good luck

.
That would be my guess also, no low speed circuit for what ever reason, running on governed high speed circuit while under load, engine has no fuel to run on when A/C cycles and removes the load due to low speed circuit being plugged.

Dieselclacker

[Hammerdown]

Guess I'll have to find a maintenance or repair manual so I'll know what to play with on the carb. Thanks for your help.
Dick

[D&J]

Originally Posted by Hammerdown

Our Onan 5500 runs fine under load, usually with roof A/C but when the A/C cycles off, the generator runs for about 10 seconds and shuts down. It will restart but won't keep running unless under the load of the roof A/C. Any suggestions on what to look for?
Thanks,
Dick

It sounds like you need to remove the carburetor and clean it, I think it's not getting fuel through the primary jet that's used at low load but it's getting fuel from the jet controlled by the governor under heavy load.

Denny

[HoRotica]

Have you tried flipping the breakers off on the generator when its cold and starting it up like that?

Chris

[Hammerdown]

Thanks for your help and direction, here's what worked. Started the generator with the a/c switch on and it ran like it has been. I had removed the air filter cartridge. I shot some choke and carb cleaner in short bursts into the carb, turned off the a/c and shot more cleaner in and it quit in 5-10 seconds. I let it cool for an hour. Started it again with the a/c on, let it run for 5 minutes, shot some brake cleaner in the carb, turned off the a/c and shot more brake cleaner in and that did the trick. It ran with the a/c off for 5 minutes, back on for a couple of minutes and back off again, it kept running at roughly the same speed whether the a/c was on or off. I think I'm back in business.
Thanks again,
Dick

[ronspradley]

I do not understand using brake cleaner on carb? Why brake cleaner and not carb cleaner? I do not want to question success, but what is up with the brake cleaner? ronspradley

[Hammerdown]

Brake cleaner seemed to dissolve the gunk quicker and it evaporates faster. I used carb cleaner first.