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Hank F.
Hank F. , Technician
Category: Small Engine
Satisfied Customers: 14365
Experience:  Certified on Onan and Generac generators
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Hello, Hank I have an Onan Marquis Gold 5500 gas carb generator,

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Hello, Hank
I have an Onan Marquis Gold 5500 gas carb generator, model HGJAB. The unit has 1800 hours and the only problems prior are the vacuum choke pulloff failing twice. Recently the unit will shut off for no reason, code 36 (engine stopped without command from controller) restart 2-5 minutes later, about 20 times. Now starts and shuts off when starter switch is released. Replaced controller, same. Inpected brushes fine. Starts and dies as soon as you let go of starter switch.Thanks, XXXXX XXXXX Do I trash it or fix it. There is no competent repair facility in the area.


Thanks for requesting me!

With this set, unless both the stator and rotor happen to be shot, definitely fix it. It's too bad you have already replaced an expensive controller.

Code 36 is almost always fuel related.

As far as the shutting off when you release the start button, this is the single most common complaint with Onan. It has several causes, but is most often caused by the set not producing electricity.

The first thing you need to do is to verify whether the set is actually producing or not.

Remove the control cover to access the circuit breakers. Set your meter to VAC and connect the negative lead to a good ground. Connect the positive lead to the back of a circuit breaker on the wire marked T1. Press and hold start for about 5 seconds.

How much voltage is being produced?

I am also assuming you have checked the oil level to ensure it is full.

Customer: replied 6 years ago.
Oil good, oil pressure switch is good. I have the service manual, stator and rotor test good. Voltage bounces around when start switch is held saw 30vac and 50vac. I removed the lower cover and you can spin the rotor easily (engine does not turn with it). From what I see in manual the pulley's are bolted , no clutch, and spring loaded idler keeps pressure constant. When starting the rotor starts spinning, but maybe not fast enough. Have you seen any belt or pulley problems. Do not hear any abnormal noises or squeals , but hard to hear clearly with starter engaged. It seems to me that when you turn the rotor you should feel the resistance of the engine or the belt slipping. Thanks Steve

You are correct there. You should not even be able to turn the rotor by hand. This belt is very tight.

I honestly have not had an issue with the drive belt on any of these units. When Onan first came out with the vertical configuration, I thought they were crazy - just something else that can go wrong. But I have yet to see one fail.

If the problems are caused by a loose belt, it should be giving either a Code 13 - Under voltage or a Code 15 - Under Frequency, or both.


Recheck your code again.


Also check your flash voltage while cranking. Set your meter to VDC and connect the positive lead to the lower brush wire, and the negative lead to the upper brush wire while cranking. You should see at least 12V, and ideally 20-30V.

Hank F., Technician
Category: Small Engine
Satisfied Customers: 14365
Experience: Certified on Onan and Generac generators
Hank F. and 6 other Small Engine Specialists are ready to help you
Have you found anything yet?
Customer: replied 6 years ago.
No code , but disassembled and found broken pulley coupling. I wish I had known that there was a rubber piece that could cause this. Replaced and runs fine.

Glad to hear it.

As I stated earlier, I really don't like these vertical configurations. All those extra moving parts are just something else that can go wrong. Give me a horizontal direct drive any day.

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