Generator help

[smh1040us]

My onboard generator starts and runs as long as I keep my finger on the "start" button as soon as I remove my finger it stops.

Has anyone had this problem and if so did you find a solution?

Thanks for any ideas and help.

Mark

[j-d]

To the OP:

We can't help further without Make/Model/Spec on the Generator.

About battery charging:

Some Generators charge the House Battery at a very low rate when running.

On Shore Tie, or with Generator running, your coach's Converter/Charger should charge the Coach (House) Battery.

With Engine Running, the Engine/Chassis Alternator should charge its battery (the Engine/Chassis one).

With Engine Running, the Engine/Chassis Alternator should ALSO charge the Coach/House battery.

This Engine Running/House Battery Charging is made possible by a small continuous duty Relay (possibly under the Hood, possibly near a Battery). It does this because a wire from the Engine's Ignition Switch energizes it to connect the House battery for charging while you drive.

This relay is also your Emergency Start. It energizes to connect Coach to Chassis batteries when you push that dashboard button. You're giving yourself a Jump Start without having to use Jumper Cables.

[77rollalong]

Here is some trouble shooting hints for the 4000 emerald 1 may help..
https://www.flightsystems.com/pdf/onan-rv-troubleshooting-guide.pdf

[maillemaker]

Thanks for the replies.

The generator is an Onan 4000.

This is insufficient information. We need the model number. There should be a nameplate on the side of the generator with the model number.

My problem is also confused by the fact that my engine batteries do not charge the house batteries. Could that be the same problem as the generator?

Your "engine batteries" do not "charge the house batteries". In fact there are electronics in place to make sure that your engine battery cannot be drained by your house system so that you don't end up stranded.

However, your engine can charge both your engine battery and your house batteries. There may be a switch you have to set that enables this. In my RV, there is a 3-way rocker switch on the dash. When held one way, it gangs the house and engine batteries together so that you can get a "jump" from your house batteries to start the engine if your engine battery is dead. You have to hold the switch down to get this ability and it releases as soon as you let go.

Rocking the switch the other way it will stay that way, and in that mode when the engine is running it will charge your house batteries.

Note that with my RV if you accidentally leave that switch in the "charge" mode and you run the engine and the generator at the same time it will burn out the voltage regulator in both the vehicle and the generator.

I am further frustrated by the fact that none of the RV dealers around me will work on generators and they don't have a suggestion on who will work on them.

This is not terribly surprising to me. Small shops have to hire in people to do generator work for them. Real small shops may not bother.

It also shows no amp input when I am holding the generator start button down.

Again, any ideas are appreciated. RV.net has been a great resource to me in the past.

In some, if not all Onan generators, when you press Start all safety interlocks are defeated. So the engine is not checking for low oil cutoff, no AC cutoff, etc., so the engine will run so long as you hold start. When you release start, the safety interlocks are enabled, and there are numerous locks that will shut down the engine if they detect a fault condition. For example, low oil, no AC current being produced, etc.

The generator will flash codes suggesting the problem.

This depends on the age of the generator. Mine has no display panel. It's an Onan 4BGEF Spec G (circa 1990).

Steve

[tatest]

The generator will flash codes suggesting the problem.

Mine went through a period of shutting down on release of the start button because once the generator came online it detected a short in the 120V house system. Another time it was a problem transitioning from idle to light load running speeds, codes for that suggested an ignition or fuel system problem.

Not many RV dealers are licensed Cummins/Onan service points, although a few will do limited work, like changing a spark plug or an oil change.

[powderman426]

Some of the older Onans had a wire wound resister in the start switch circuit. It allowed for higher voltage to start then when the button is released it put the resister in circuit to cause a voltage drop back to a lower voltage to save wear and tear on the points. If the resister burns out you get an open circuit when you release the start button. It then shuts down.

[DrewE]

The DC system is pretty much independent of the generator...or, more precisely, if the generator starts and runs at all, the DC system is sufficient for it.

The generator in an RV is usually not set up to charge the batteries directly, but rather the converter charges the house battery from the AC power that the generator produces. You probably aren't seeing any charge current because the transfer switch hasn't switched over to the generator, either because it's producing no output (and hence shutting itself off) or because the time delay hasn't been satisfied yet. That should take care of itself when you get the problem with the generator sorted out.

There are several reasons why the generator might shut itself down to protect itself, some of which depend on the spec level of the Onan. If it doesn't detect output it will shut down because this can indicate a short in the generator wiring that, if left running, could cause a fire (perhaps among other reasons). Some have other sensors as well for e.g. oil level.

The house batteries should charge from the vehicle engine alternator when the engine is running, it's true, but that's a completely separate system from the generator. There's some sort of isolation device that only connects them together when appropriate, either a high-current diode or a relay/solenoid based system which may have very simple controls or somewhat more complex bidirectional controls (to allow the chassis battery to charge from the converter if needed), but neither is directly related to the generator operation.

[smh1040us]

Thanks for the replies.

The generator is an Onan 4000.

My problem is also confused by the fact that my engine batteries do not charge the house batteries. Could that be the same problem as the generator?

I am further frustrated by the fact that none of the RV dealers around me will work on generators and they don't have a suggestion on who will work on them.

The RV is new to me and I did install a Victron battery monitor when I first got the RV. The monitor seems to work fine when connected to shore power or unplugged. However it does not show any amp input when the vehicle engine is running. It also shows no amp input when I am holding the generator start button down.

Again, any ideas are appreciated. RV.net has been a great resource to me in the past.

Mark

[j-d]

We really need Make, Model, and if ONAN, a Spec Code. With that info we can probably provide a manual with troubleshooting chart, or relate experience with one like yours.

The premise that Start Mode bypasses a bunch of sensors and safeties is probably correct. You need specifics on how your genny works that out, so you can start to figure out what's causing the shutdown. Could be a problem where genny thinks it has a problem and doesn't, but could also be protecting itself from a real fault.

[77rollalong]

i have had a similar problem with an older onan, when the starter button is held the ign power comes from the starter circuit, when its released it has to run off the generator, if the generator does not put out power it dies. could be a faulty controller board, fuses, mine was dirty commutator for the exciter from lack of use. i ended up jumpering the ign to 12 V constant so the motor would star running , and running a 100W light off the output to put a load on it till the slip rings cleaned them selves up, then hooked the ign back up as normal..

[gbopp]

Did you check the oil level in the generator?

[Isaac-1]

It is shutting down on safety or is not generating AC power, if you tell us the brand a model we may be able to point you in the right direction.