Onan Generaor - 10 yr old

[TC_Z]

We have a Onan Marquis Gold 5500 watt generator. It is 10 yrs old. I service oil and air filter. We have never had a problem with it. It has 500 hrs run time. When it used to start it would crank then run smoothly almost immediately. Now when cranked it sort of putt, putt, putt, putt, putts, for 10-20 seconds then runs smoothly. Trying to decide if I should take MH in to get generator serviced. However not sure what they would do. Would they clean carburetor, or replace it? other? Or would they tell me it is 10 yrs old and I ought to buy a new one? Or is this the expected behavior when 10 yrs old and it is ok, this is normal, no service needed.

Wish I had more confidence in the service folks. Seems like when you have a MH they think money is not an issue for you. We are still making payments. What are your thoughts?

[Passin_Thru]

i thought of it because I saw a movie where a guy was mad at his girlfriend so he brushed the dog's teeth with hers.

[77rollalong]

my onan has and electric choke pull off (1977) the newer ones have a vacuum pull off, i had to rebuild the carb for ours last year it did run , but was a bit hard starting at times. I had picked up a can of industrial carb cleaner and soaked all the metal parts in it , (no plastic or rubber) as this cleaner will remove the paint and eat anything not metal. i also added an extra inline fuel filter with a clear case as i know there is junk in my main fuel tanks as i have not had a chance to drop them and have them steam cleaned as yet. there is really not too much too the carbs and the orifices are quite small so a little bit of crud messes them up. I also found that the previous owner had put the choke pull off spring in incorrect so as it heated up it would give it more choke instead of taking it off..

[Jim]

Passin Thru wrote:
If that one has the automatic choke (not sure if its auto or heated intake) the solenoid on the mixture solenoid could be going bad. Pull the plug with 2 wires to it from the float bowl and clean with a carb cleaner and tooth brush, preferably your wife's. They usually cause surging. It's a very easy fix.

Buhahahahah. Snort. Thanks for that.

[Passin_Thru]

If that one has the automatic choke (not sure if its auto or heated intake) the solenoid on the mixture solenoid could be going bad. Pull the plug with 2 wires to it from the float bowl and clean with a carb cleaner and tooth brush, preferably your wife's. They usually cause surging. It's a very easy fix.

[Rick_Jay]

TC&Z,

I agree with checking out the choke. But before you do that, is there any possibility the altitude adjustment got bumped when you were working on it? Our Onan has an adjustment for the altitude for which it's being operated. Depending upon the altitudes and/or setting involved, if it's not adjusted properly it might look like a choke problem on start up.

Good Luck,

~Rick

[mcal63775]

Use Seafoam every time you fuel. If you are be able to get premium WITHOUT ETHANOL, that will be a plus. Exercise your rig at highway speed least once a month, running generator. Use the levelers and slides. A sitting rig will deteriorate way faster than one getting used.

[sehunter]

I agree with Richard my generator was doing the exact same as yours. I visited our local Onan shop and was told they have replaced hundreds of the vacuum chokes on the carburetor, it sounded like there is a service life on these things. If you are able to service your RV you are more than capable at replacing it.

[roam1]

sounds like the automatic choke to me to, as they get older they can stick and take a bit longer to function.

[ArchHoagland]

I use Seafoam once every year. I put 5 to 6 cans in the gas tank just before a long trip.

During that trip I'll run my Onan 5500 for at least an hour.

[koda55]

I agree with everyone that has said to use seafoam. I use it in all my gas engines.
Our RV has a 150 gallon tank and I put 3/4 of a gallon in the diesel every 4 months. I run the generator about 1/2 load for about an hour to make sure it gets into the generator.

[Farmboy666]

TC&Z wrote:

Farmboy666 wrote:
It sounds like a fuel issue but 20 seconds really isn't an issue. Does it get fuel from main tank or it's own? Either way I would try some Seafoam first and that should help clean things up if it's fuel system.

Appreciate your suggestion. Our gen gets its fuel directly from the main MH tank. Unclear to me how you want me to introduce the Seafoam into the generator's fuel line. Please provide a bit more info how to do this, apologize its not obvious to me... thx

Mine runs off the main tank and the gas line to the generator has a quick disconnect to the main tank, I unhook it and put it in a gas can and prime. As some have said it may not fix the problem but is an easy and cheap first step.

[ScottG]

Sounds like the choke is sticking on. I would clean the area thoroughly with spray carb cleaner.
Can't hurt!

[gbopp]

TC&Z wrote:
Appreciate your suggestion. Our gen gets its fuel directly from the main MH tank. Unclear to me how you want me to introduce the Seafoam into the generator's fuel line. Please provide a bit more info how to do this, apologize its not obvious to me... thx

You can put the Seafoam in the MH fuel tank, I believe they recommend 1oz Seaform per gallon of gas.
Or, you can rig up a small external tank and gravity feed it to the carburetor.
Another option, which I do, get a can of spray Seafoam and spray it into the carburetor while it's running (remove the air filter). Do that a couple times and then stop the generator and leave it sit for an hour or two. This will obviously not clean the fuel line but, it does a good on the carb.

[RLS7201]

Your problem is most likely the choke pull off. The puff, puff you are hearing is an overly rich fuel mixture. Once the engine starts the choke needs to be opened about ½ way, which is the function of the choke pull off. It can easily be tested by removing the vacuum hose and attaching a longer hose that you can suck on. With applied vacuum, the pull off should move to end of travel and stay there. If not, replace the choke pull off. Seafoam will not cure your problem.

Richard