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Ask Hank F. Your Own Question
Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 14985
Experience:  RV tech since the beginning of the millenium.
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I have been reading all these posts. Seems that code 36 is

Customer Question

I have been reading all these posts. Seems that code 36 is pretty popular.
JA: Just to clarify, what's the exact code? And have you tried to reset it?
Customer: Yes. I have a QG4000. Starts up and runs for a shot time and shuts down. We have checked all the fuel issues. When it shuts down we loose ignition power. The board is shutting down the unit.
JA: What is the model/year of your RV?
Customer: 2008 toyhauler the generator model is 4KYFA-6747K
JA: Are you fixing your RV yourself? What have you tried so far?
Customer: We are attempting to diagnose the problem. We repair construction equipment. This is for a friend of mine. No good deed goes unpunished.
JA: Anything else you want the mechanic to know before I connect you?
Customer: well, I guess I should ask what the fees are for this help.
JA: I'm not sure of the exact price, but there's only a $5 deposit. The rest of the price information will be on the page I send you to.
Customer: I see.
Submitted: 7 months ago.
Category: RV
Expert:  Hank F. replied 7 months ago.

Hello, my name is ***** ***** I am going to assist you with this.

While the genset is tunning, does it run smoothly, or is it surging?

How long does it run before it shurs down?

When it shuts down, does it just shut off like someone turned it off, or does it start surging before shutting down?

When it shuts down, does it start right back up, does it only restart eith extended cranking, or does it have to sit for a while before it will restart?

Customer: replied 7 months ago.
The run time varies. Never more than a minute. It shuts down like it is being turned off. Not like running out of fuel. We had a meter on the run power circurt. It's like the board is shutting it down.
Expert:  Hank F. replied 7 months ago.

If the valves are good, do a compression test and make sure you don't have a bad ringThe controller is shutting it down - that's why a code is being set.

Code 36 means that the controller does not know why the unit shut down. It is most often a fuel issue, but can also be an engine issue.

Since you are certain it is not a fuel issue, start eith the valves. Make sure both are gapped to .002". Onan had an issue with bad valves about the time your unit was built. Rocker arms ha a habit of cracking.

If the valves ate good, do a compression test to see if you have a bad ring.

Let me know what you find.

Customer: replied 7 months ago.
I checked the valves. One was loose aprox .009" and the other tight aprox .001". Can't don't have room for a compression gauge but I don't suspect that an issue. Engine runs too smooth. Adjusted both valves to .002". Restarted unit and it ran for about 3 minutes. Seems to run a little longer when it is cold. It shut down, light on start switch went out upon shut down. Just a hard shutdown like it was turned off. Would not restart for about 30 seconds. Then restarted and ran for about 1 minute. Same thing, shut down. What would tell the board to shut it down?
Expert:  Hank F. replied 7 months ago.

If something was telling the controller to shut the unit down, it would be setting an appropriate code.

Code 36 means that the unit shut down, but thecontroller doesnt know why. It is either fuel supply, or engine mechanical, or a bad controller.

The controller would know if someone hit the stop switch, low or high voltage, low or high engine speed, or a faulty field.

Customer: replied 7 months ago.
We were also getting a 14 code. This unit has very low hours. It ran with no problems and then this just started. What would be the procedure to narrow it down?
Customer: replied 7 months ago.
I don't think it is the fuel supply. Doesn't seem to be anything mechanical. It is odd that the engine will run for a longer time when it is cold. After shutdown it won't start back up for a while. Light flashes while cranking. Then it starts up again but for not as long. Almost like an electrical component is getting hot and breaking down.
Expert:  Hank F. replied 7 months ago.

It does sound like that, and a bad coil or magneto will do that, but normally when a coil or magneto goes bad, it will run for 10 - 20 minutes before it shuts down, and then must sit for a half hour or an hour before it will restart.

The fact that it is only running for a minute, and will start back up in less than a minute does not indicate a col or magneto breakdown. That is not even running long enough for them to heat up.

A bad controller might do that, but with the cost of a controller, I would not advise you to just get a new one. It would be best to have the genset fully tested by an authorized Onan dealer that has a Break Out tool. It is a tool that can be plugged in place of the controller, and will allow the engine to stay running while the entire genset is tested. If every other subsystem tests good, then the controller is replaced.

Customer: replied 7 months ago.
Expert:  Hank F. replied 7 months ago.

Not a problem.

If you have trouble finding an authorized shop, let me know.

Thank you for using Just Answer, and please take a moment to rate my performance.

Customer: replied 7 months ago.
Your not going to believe this. I know I don't. After rechecking the unit. Found that the wrong spark plug was installed in the unit. I wouldn't have believed it myself. After installing the proper plug. We started and ran the unit for an hour. Then for another hour and a half with a load. Never dreamed a spark plug would cause those kind of symptoms.
Expert:  Hank F. replied 7 months ago.

Actually, I can believe it. I have seen some strange things in the 15 years I have been a generator technician.

Obviously, I have no way of knowing something like that. That is the type of thing that needs to be physically seen.

I am glad that it was something so simple.

Thank you for using Just Answer, and please take a moment to rate my performance, so I get credit for my time.