Onan Marquis gold 5500 Starts won't run

My Onan Marquis Gold 5500 series Gasoline Gen Starts and then dies in 3 or 4 seconds. There is plenty of fuel and oil. I went to start it the other day and it would start right up but then dies. I tried holding the starter switch in to see if it would keep running, But it won't. Where do I start trouble shooting the problem. Any suggestions.
Re: Onan Marquis gold 5500 Starts won't run

Sounds like the oil sensor is bad. Even though you have oil in the engine, the sensor does not know that. Try shorting the wires at the sensor and see if it runs.
Re: Onan Marquis gold 5500 Starts won't run

I was told by a mechanic at a Mtr Hm Dealership that the Carb is probably plugged or dirty. He told me I would have to buy a new one as it can't be cleaned or repaired. Why can't it be cleaned or a repair kit put in it? A new one is $295 Can anyone shed some light on this. I also get a error code Flashing light 33 or 32.
Re: Onan Marquis gold 5500 Starts won't run

Here is what I did so far. I started really checking into this matter and talking to several different people about it (i even went to a Onan repair depot and talked to a factory mechanic. Here is what I learned. These carburators on this model Generator are very touchy. Even a tiny bit of varnish or gum Not running for several weeks or a month cause's The majority of the problems for this generator, The altitude adjustment on these carbs if disassembled, has to be calibrated with a special machine. I removed the carburator and used a spray can of Carb cleaner and removed the float bowl and made sure that there was no varnish or gum in the unit. also sprayed into all orifice openings and made sure that none where plugged. I still have the same problem. The fuel pump is OK and so is the oil sensor. Error code 32 probably indicates that it is the brushes, stator or rotor or the control module board.

Warning. If you attempt to clean the carb your self. Do not I repeat do not remove any jets or the altitude control. If you do you will have to buy a new carb $218 and labor. I did not remove anything lucky for me as the carb is not the problem. I would try installing or cleaning the brushes But there is very little space and it takes a small hand to get in the area where they are located. I think I will take it to the service depot and have them fix it..


Senior Member
Re: Onan Marquis gold 5500 Starts won't run

mel that was some good info, I have the same genset however I start mine once a week or every 2 weeks just to keep the varnish from builing up. wish you well on getting your repaired
Re: Onan Marquis gold 5500 Starts won't run

I took it to the Onan Service Depot this morning. They say I have to have a new Carburator and maybe a Controller board. I questioned them at great length. and here is what I found. They hooked a special circuit board up to the generator that bypasses all of the safety features and permits the unit to run it would run but was running rich and the choke butterfly had to be held open. to keep it running. the choke is controlled by the controller board. But they said that it will do that when there are problems with the carburator. I will find out Wednesday.. They had to order the carb. I had to pay up front for the part. I will keep the old carburator just in case. I was told that the carburator is the throw away type as they cannot be rebuilt. no extended warranty will pay for any carb work period. So I am stuck. But they will pay if the Controller board is bad.
Mel :(