Onan Generator Starts Then Shuts Down (Fixing Code 36)

Generators come in handy. That is when they work like they are supposed to. They provide the power you need to run your RV when camping. But once in a while, your generator may act up and send out a code message. Knowing what the code means and how to fix it is information you need to know.

Code 36 may be a bit difficult to understand as it is used often by the control module. But the handbook for Onan says that you need to check the fuel supply and fill the gas tank as needed.

There is more to learn about code 36 and how to fix what ails your generator. To learn all about this issue just continue to read our article. It has the information t make your generator work better when the code 36 appears.

Onan Generator Starts and Dies


It is possible for your Onan generator to start up fast and quit just as quickly. That is because many generator models are designed to shut down if there is a quarter of a tank of fuel left in the tank.

But gas issues may not be the only reason why your Onan generator shuts down soon after it starts. You could be having an electrical or carb issue. If it is the carb, then you should have some sputtering before it dies.

If it is an electrical issue, then your generator just may die quickly without any warning sounds. One source of the trouble, if electrical, may be the generator. To diagnosis this possible source, you need to start up your generator again and attach a meter to it.

If you are not getting 120 volts AC, then you have a generator issue to deal with. Once you make that determination, you will still need to investigate which part of the generator is the actual source of the problem.

You do not want to waste time chasing after the wrong part so be thorough and make sure you find the source before you go changing out parts.

Onan Generator Code 36

One of the main issues with a code 36 is that it is applied to more issues than just the fuel level. It can be signaling a problem for the fuel pump, clogged filter, dirty carb and a lot more possibilities.

Code 36 seems to be the catch-all error code and you cannot assume you have the right fix for every time the code flashes. Sometimes, the control module does not see the correct voltage for both legs of the generator. When this happens, it still sends out a code 36.

You can spend some time going by the book and making all the fuel fixes. If that is the problem, and it goes away by following the book, then great. But if it doesn’t, then you need to look past the fuel issue and into the electrical system to find the source of the problem.

This extra effort may save you a trip to the dealer and a qualified technician. It may also save you a little money as you can find the source with the help of an inexpensive meter and not pay high labor costs for a tech to do the same thing.

Before assuming you know the problem, go the extra mile and make sure the fuel system is the problem first.

Generator Runs For a Few Minutes Then Stops


There are several sources that may cause this issue to rise up and spoil your day. The first source could be your fuel cap. If the cap is not venting properly, then your generator may stop working soon after you start it up.

All you have to do is open the fuel cap a little bit and start your generator again. If the generator runs like normal, then you need to replace your fuel cap. Second, you can also take the fuel line off the fuel pump and see if enough fuel is getting through to the engine.

A third issue may be the armature coil. If the generator is not getting enough spark, then the armature coil may be going bad and not producing the spark you need to run your generator.

One way to make sure it is the armature coil is if your generator needs time to cool down before starting up again. Usually, you may not be able to re-start the unit until 30 minutes have passed by.

The armature coil is normally located next to the flywheel making it not to difficult to find and replace. The last source to check would be the fuel pump. If gas is not getting through then you may need to replace that part as well.

A pinhole in the diaphragm can cause the same problem as well.

Onan Generator Stops Running When Hot

Once again there are several possibilities for when this issue takes place. One possible cause, according to the handbook, is that the airflow is restricted and the engine is not getting cooled fast enough.

The reasons behind this possibility are that there is some debris blocking the inlet or outlet ports. This debris ranges from dirt and leaves to mice nests and other small animals making their home in these outlets.

Another issue that may cause this problem is that dirt and oil are covering the cooling fins. To solve this problem, you need to clean away all the dirt and oil from the cooling fins, including the internal passageways.

Other sources can be a vapor lock, air intake is set at cold weather settings, or the choke is set wrong. There are a variety of things to check before finding the right answer.

Part of your solutions may include adjusting the fuel mixture screws, check the float level, dirt got into your carb and you need to clean it out, and you may have a vacuum leak.

Then one simple source that may be very hard to fix, is that the weather outside is just too hot for the generator to work properly. Sometimes 90 degrees F is just too hot for the unit to handle and it overheats then shuts off.

Diagnosing Different Onan Generator Issues


One issue that was mentioned earlier was vapor lock. This can happen, especially on an extremely hot day. To figure out if vapor lock is the problem causing your unit to shut down quicker than it started, just pull the incoming fuel line off the fuel pump.

Make sure to have a bottle handy to catch any fuel that may come out as you do this. Make sure the open end of the fuel line is in the bottle. Once the line is off, turn the engine over. If no fuel comes out then you have vapor lock.

To fix this issue, you need some old fashioned wood clothespin. Put one or more, more is recommended, on the fuel line. The wood absorbs the heat and should help clear the fuel line. Once the line is cleared re-attach the fuel line and start your generator.

Another issue may be the fuel pump itself. If you can, insulating it may help prevent vapor lock and other fuel delivery issues. Also, insulating the fuel line with a common garden hose may help you keep the fuel flowing nice and steadily as you operate your generator.

If you are not having a fuel delivery, etc., issue then you need to check the electrical side of things. We have already talked about the generator but there are other electrical components that may trigger the error code 36.

The exciter circuit may be the problem or the ignition circuit. Then there is the possibility of something wrong with your open or shorted stator windings or rotors, brushes, slip rings and so on.

Error Code 36 Advice

The key to fixing the error code 36 is to try the simple things first. With this starting point, you may find the solution quickly and not have to spend a lot of money buying new parts.

Take your time as well as you do not want to rush to judgment. Use a voltmeter to help you check the electrical side of the unit. You never know when one of the electrical parts is sending out the error code and you should double-check electrical parts before buying anything.

Some Final Words

Modern generators have a lot of parts that can go bad. That is why the manufacturers provide error codes. These codes usually help you find the trouble, then you can check the manual for solutions.

Unfortunately, this is not always the case and you have to go beyond the manual to find the true source of the problem. Knowing what to do will save you time and trouble. It may also save you lots of money.

Error codes generally help but they may send you in the wrong direction as well.

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