18 replies to this topic

[Dune Cruzer]

So my Onan Marquis Gold 5500w generator was giving me a hard time to start. Ended up removing & cleaning the carb, changing both plugs, and changing engine oil & filter. Got it running, except now it surges with or without a load. The throttle lever/choke arm jumps with each surge. No codes flash. Just want to get this thing to idle properly. Anyone have a similar problem? Any ideas? Thanks for any help.

[dunefreak]

Usually the mixture control solenoid sticks and causes that. I've had that issue before. It screws in to the bottom of the float bowl and has 2 wires going to it.

[tatooedwhtboy]

After the ordeal i just went through with my gen, try running a can of Onan "C4" through it. Disconnect your fuel line from the carb, crank it over while you spray the C4 in, gen should run off of the C4. The gen will smoke and spit and spudder, have no fear it is normal. Make sure to remove your air filter before doing this. Run it with the C4 for a couple of seconds each time. reconnect your fuel line then finish off the can of C4
i did these steps to mine along with replacing the fuel pump and filters. gen runs like a champ now. I swear by this stuff. hope that helps

[goodguys75]

So my Onan Marquis Gold 5500w generator was giving me a hard time to start. Ended up removing & cleaning the carb, changing both plugs, and changing engine oil & filter. Got it running, except now it surges with or without a load. The throttle lever/choke arm jumps with each surge. No codes flash. Just want to get this thing to idle properly. Anyone have a similar problem? Any ideas? Thanks for any help.

it is probabley trying to look for a load....they surge when there is no load on them...turn some stuff on and it should stop....my guess

[dunefreak]

it is probabley trying to look for a load....they surge when there is no load on them...turn some stuff on and it should stop....my guess

Surging isn't normal. When there is no load, they idle smoothly.

[tatooedwhtboy]

sorry its 4C not C4.

[Dune Cruzer]

sorry its 4C not C4.

lol, isn't C4 an explosive? Where can I get the 4C? Never heard of it before.
Dunefreak-I know of the part you're speaking of. I'll give that a shot, weather permitting.
Thanks guys.

[dunefreak]

lol, isn't C4 an explosive? Where can I get the 4C? Never heard of it before.
Dunefreak-I know of the part you're speaking of. I'll give that a shot, weather permitting.
Thanks guys.

Only chitty thing is it's not available separate. You could try to carb clean the hell out of it and tap on it to free it up. Otherwise a new carb is about $180.

[ynot]

Only chitty thing is it's not available separate. You could try to carb clean the hell out of it and tap on it to free it up. Otherwise a new carb is about $180.

If you have to go to Cummins for the part let me know and I will give you my Cummins power club member # and it saves you 10% ON ALL PARTS AND LABOR.

[tatooedwhtboy]

you can get the Onan 4C and camping world, johnny walker or even cummins

[Dune Cruzer]

Well, I removed the mixture control solenoid under the float bowl today. It's not stuck, still has it's "plunging action". Next I'll probably try the C4, along with a new fuel filter and see if that helps.

[tatooedwhtboy]

with the Onan gen, you will have 2 fuel filters. there will be one mounted under your rig and one attached to the fuel pump itself. My fuel filter under the rig was clean as can be, the filter attached to the pump was clogged somethin fierce. just a lil FYI

[Runnin A Fever]

<sub>I removed them both, too expensive for Onan parts. Went with a regular fram inline filter that I can see through to monitor. I feel your pain, been through many issues with mine due to sitting too long by the previous owner. I had to clean the carb jets, they were clogged and replaced the pump. Runs good now - knock on wood - and I make sure to start it at least every other weekend.

Stick with it, you'll get it figured out.</sub>

[Sincity_blondie]

Mine is doing the same thing. Ill have to see if I can get someone to check

"Usually the mixture control solenoid sticks and causes that. I've had that issue before. It screws in to the bottom of the float bowl and has 2 wires going to it. "

I tried running the micro just to put a load on it and still does the same thing.

[Dune Cruzer]

Well, it turns out it needed a new carb. Seems to be a common problem with these generators. Runs like a champ now. Thanks for all the help everyone!

[bp-guy]

Onan's are very touchy. You need to start them up atleast once a month or just add an inline shut off valve and let the gen run empty. The gas evaporates and the varnish left over gums them up quickly.

[Dune Cruzer]

Onan's are very touchy. You need to start them up atleast once a month or just add an inline shut off valve and let the gen run empty. The gas evaporates and the varnish left over gums them up quickly.

Exactly. I'm going to make it a habit to start it up around the 1st of the month, and run it for about an hour under load to try & prevent this from happening again.

[tatooedwhtboy]

I have to pay to store my hauler, so every month when i go to pay my storage fees i run it for minimum 30 minutes

[ynot]

I have to pay to store my hauler, so every month when i go to pay my storage fees i run it for minimum 30 minutes

Make sure you put a load on it while running them. It's what they were meant to do.