Onan 5.5 won't remain idyling/running??

jwd53 · 01-18-2012, 11:29 PM

The generator first would only remain idyling for a few minutes and quit under load. I changed the gas filter and sprayed about a can of carb cleaner into the running unit. It now runs for about an hour and quits under load. I have over 1/2 tank of gas in MH. Am I on the right track or what??? Please help. oh yeah I did not run the generator monthly, as advised.

Ret Smokey · 01-19-2012, 03:49 AM

What you are describing is EXACTLY what happened to me last summer. We purchased a motorhome from a private party who said he ran the generator every month. When the air conditioner would try to start, it would throw the generator out. Found a Onan generator service professional in the town we were in, and four hours later we were on the road again. The problem is the second stage of the carb is gummed up. He took it off soaked it and reinstalled. Load tested it and ran like a champ. He advised to run it every month at full load for one half hour. When you load it up you will hear the motor snort a bit that is the second stage of the carb kicking in. Hope this helps.

dirko · 01-23-2012, 09:59 AM

Hi Ho: Bob is right, probably a dirty carbureator. However, this might be a good time to do routine maintenance. Charge oil, fuel and air filters, change spark plugs, put in tune-up kit (points and condenser) in distributor if it has a bunch of hours, etc.

The easiest thing to do is to simply remove the float bowl and clean it out and spray a little of your carb cleaner. If this doesn't do it, then the carb has to come out and basically be rebuilt. If you haven't done that before, it is an interesting experience.

Getting to the spark plug in the rear also requires removing some stuff.

Arch Hoagland · 01-23-2012, 11:10 AM

Must be Onan 5500 day on here. Just posted this reply on another thread:

I used five cans of sea foam or Techron about once a year in my 75 gallon gas tank just before a long trip where I will burn through all the fuel. I run the generator for at least an hour on those trips to clean the carb of my Onan 5500.

So far, so good.

jwd53 · 01-24-2012, 08:00 AM

I used a can and a half of carb cleaner and have extended the run time to two hours. I also put two cans of sea form into MH tank and will see what this does. I learned that the blinking light of the on/off switch was really a pattern, like morse code. I downloaded a service manuel and was able to follow the trouble shooting guide. Who knew!!...Thank you for the input.

Paul T · 01-24-2012, 07:38 PM

After 5 years my 5.5 started shutting down after AC was turned off.
Stopped by the Onan shop in Ocala, FL and after a ¼ inch turn of the idle setting my problem was fixed at no charge. Seems it was getting a momentary under or over voltage and shutting down. The fix was based on measuring output frequency which my volt meter didn’t have a reading for. Quite simple if you have the right ezuipment.

Dunner · 01-24-2012, 10:52 PM

jwd53, what is happening is that you are slowly cleaning out the main jet of the carb. Spraying through the inlet will do nothing to clean it. The Seafoam should though. If not, take the carb off and apart and run a single strand of copper wire thru the the main jet of the carb to get the rest of the varnish out of it.

The main jet usually sits at the bottom of the float bowl and is more susceptible to getting gunked up if it sits too long without being run. Good luck and post your progress.

jwd53 · 01-25-2012, 07:48 AM

Thank you Dunner...
Hey Paul T.....which was was the 1/4 turn....right or left??

hzltf6 · 01-26-2012, 08:48 PM

Had the same problem last summer. Also thought it was the carb because of the code I was getting. A friend of a friend who works on rv's tested it and found out the voltage regulator circuit board needed changing.

jwd53 · 01-27-2012, 07:42 AM

Thanks...hzltf6

Sylald · 02-26-2012, 05:45 PM

Did you get it fixed? I'm having a similar problem. I ran it for about 2 hours today, but it surged the whole time, and died whenever I put a load on it. I put some fuel system cleaner in the tank hoping that would help. It made a little bit of a difference, but didn't fix completely...still dies under load. Got a 36 error a couple times, but there's plenty of fuel in it.

Dunner · 02-26-2012, 06:16 PM

It might work better tomorrow after the additive dissolves any varnish.

Sylald · 02-26-2012, 06:40 PM

Good point. After the first bottle didn't do it after running for over an hour, I added a second bottle but that was not too long before I stopped messing with it. I'll see what it does sometime this week.

jwd53 · 02-27-2012, 07:45 AM

Sylald,
I put 2 qts of SeaFoam in my 75 gal tank of gas to help the generator when in use. The previous process of using the 1 1/2 cans of carb cleaner seemed to help desolve any varnish in the carb bowl. with the generator running I just kept spraying into the carb just until the generator began to stall then stopped until it recovered. I just kept repeatiing the process. The generastor now runs at least 2 hours under load of a/c or heater w/o stopping. I will NOW run my generator monthly!!

Dunner · 02-27-2012, 07:54 AM

Spraying into the mouth of the carb is not going to do anything to the varnish in the bowl. It just goes straight into the engine. I think it is running better because the Seafoam is dissolving the varnish in the bowl. I would run it for short periods to get fresh Seafoam in the bowl. Or, if you have a drain on the carb, drain it then prime it to get fresh Seafoam in the bowl.

Sylald · 02-27-2012, 07:31 PM

Quote:

Originally Posted by jwd53

Sylald,
I put 2 qts of SeaFoam in my 75 gal tank of gas to help the generator when in use. The previous process of using the 1 1/2 cans of carb cleaner seemed to help desolve any varnish in the carb bowl. with the generator running I just kept spraying into the carb just until the generator began to stall then stopped until it recovered. I just kept repeatiing the process. The generastor now runs at least 2 hours under load of a/c or heater w/o stopping. I will NOW run my generator monthly!!

I put in Lucas fuel system cleaner and gum out. It seems like it helped because at first, the engine would die if I tried putting the air filter cover back on, but after while, it would run with it on. The surging got better, but didn't go away. I went back a few hours later and started it again and it ran smoothly for about 2 minutes, then started surging again. I'm going to let it set with the fuel cleaner in the system for a few days, then try again since it seems to be getting better. I just bought this trailer, and the previous owner hardly used the gen, and didn't start it or put stabilizer in the fuel. I know I will after this.

Sylald · 03-09-2012, 09:13 PM

Now it runs smooth for 5-10 minutes, or until a load is put on it. After 5-10 minutes, it dies whether or not there's a load on it, but runs smoothly up until it dies.

Dunner · 03-09-2012, 09:31 PM

How long after it dies before you can start it again?

Sylald · 03-11-2012, 09:50 PM

Quote:

Originally Posted by Dunner

How long after it dies before you can start it again?

Sometimes it will start right away, and sometimes I have to wait a about 5 minutes

Dunner · 03-11-2012, 10:19 PM

Almost sounds like the fuel filter is getting clogged up or something else is starving it for fuel.