RV-Onan Generator Repair


Old 01-30-11, 12:48 PM
Thread Starter
Join Date: Jan 2011
Location: USA
Posts: 1
Unhappy RV-Onan Generator Repair

Our Onan 5500 gas generator will not stay started. It will start as long as the start button is pushed down, as soon as you release the button the motor shuts off immediately.

The problem code shows not getting enough current. We have replaced the two batteries with new marine batteries. The old ones showed they had a dead cell in each - but new batteries did not correct the problem.

The RV unit's gas gauge show above 1/2 full.

There is oil in the generator. It had gotten low, we added 1 quarter of new oil and changed the air filter, although it wasn't dirty. We can see that gas is being pulled thru the gas filter into the gas chamber enough to run the unit.

The gas generator has 180 hrs of run time. The RV sits a couple months at a time with no use of the generator - but prior to not starting, we had been using the generator each day for 10 days prior without the starting problem. The oil got low enough before we checked it to need to add oil so the oil looks very clean.

Any suggestions?

We are considering purchasing a small 2000I Honda generator to use when we have to dry camp until we can get the unit generator running. We are on full hookup for one more week before we have to rotate back to dry camping. We are sort of isolated with the only repairman about 75 miles away. So we thought we would ask and see if anyone had had this problem before and suggestions of things we could check ourselves.
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Old 01-30-11, 01:24 PM
Join Date: Sep 2009
Location: USA
Posts: 484
I know nothing about this model generator but the problem you describe is common to others.

If it starts then dies when you let off the switch, I'd take a look at the oil level switch or oil pressure switch. It's not sensing adequate oil or enough pressure and is protecting the engine by shutting it down.

Hope it helps.
Old 02-09-11, 07:59 AM
Join Date: Jan 2011
Location: USA
Posts: 3
I have to agree, it is your switch. You can check it by removing the wire to the no oil or oil pressue switch. It should be by your filter. If it stays running get a new switch.
Old 07-18-11, 03:18 PM
Join Date: Jul 2011
Location: usa
Posts: 1
onan gen

i have a onan 5500 gen in my rv the thing will run for an hour with or without load starts and runs great. Then shuts off, after a little while starts right up.I have changed the oil, filter, oil psi switch, plugs , cleaned the carb, put new fuel pump on changed the gas line that goes to gas tank still does the same thing. can anyone help.
Old 08-12-11, 06:35 AM
Join Date: Aug 2011
Location: USA
Posts: 2
I had a 1978 model Onan 5500 that had this same problem as Charles. Tried everything with no luck. Then this wise old man told me to unhook the electric choke and put on a manual cable. Problem solved. Can't say this is you guys problem but it's worth checking out.
Old 02-20-12, 04:59 AM
Join Date: Feb 2012
Location: usa
Posts: 1
Generator does not see any generated power so it will not keep running.

Sorry but I am all to familiar with the problem you are having. Happened to me also. The control board is not sensing any or too low generated power output. This is caused by either a relay in the control board not functioning or no power being generated. The control board is not a big deal, but if the generator is not capable of producing power that's a big deal (expensive). It will cost you about a $100 to find out (if you can find a GOOD repair shop). Typically they want to charge you a lot to remove the generator from the RV to just see what is wrong. I removed mine by myself and was not lucky; the rotor came apart -- replaced the whole generator with another brand. Not very happy with the newer Onan products. Good luck.

PS: My old one is still in the garage where I will take it apart someday and try to fix the rotor if I can find one cheap somewhere

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