Generator runs only while holding start button

[tinyhouse]

Hi. I had the same problem with my 97 Chinook. After reading all the trouble shooting and manuals for the generator I narrowed it down to the oil sensor or the generator was not producing any power. By the way if it starts and runs with your finger on the starter it's not the carburetor. Simple test, connect a 12 volt lead to the fuel shutoff on the bottom of the carburetor. If it continues to run after you take your finger off the start switch then it's not getting 12 volts from the generator. Once you take your finger off the starter the generator has to produce it's own power to keep the fuel switch open when running. I took the unit out last winter. Cleaned out all the mouse nest and crud out. I then took a long stick with a small scrub pad and polished the rotor so it was shinny copper again. They sell what's called a Slick Stick but I made my own. Not sure if you can get to the rotor with the unit in to chinook and the cover on. Fired right up and ran well. Re installed it and it runs well under load. Hope this helps some.

[chin_k]

In addition to JabberBox's link, take a look at the service manual and see if you can figure out why it is not cranking. Onan representatives are helpful, and sent them email, and they will give you documentation, etc..

I agree with other folks that your genset symptoms are not consistent with carburetor issue. At least it need to crank and stay on for a few seconds if it is due to carburetor or altitude setting. It is a pain to get to the adapters for troubleshooting because it is not easily accessible, but it can be done. The first thing to verify is to make sure the cranking motor have the power from the battery, and you go to fuel and oil level, etc., I think the service manual have the details.

[inacioface]

Ok, so I followed this trouble shooting guide: https://www.flightsystems.com/pdf/onan- ... -guide.pdf

I referenced the "check cranking" section which states:

CHECK CRANKING Try to start the engine. If it does not crank, check the control fuse (5A Slo Blo, except models with electronic governor 10A). If the fuse is good, jumper the positive battery post to the coil terminal on the start solenoid. If the engine cranks, there is a poor connection, wiring damage or the control board is defective. If the engine cranks when the BATTERY POSITIVE pin is jumpered to the START SOLENOID pin on the control board, the board is defective. NOTE: The battery voltage should not go below 9.5 VDC during cranking.

My fuse is not blown and when I jump the positive battery connector to the start solenoid terminal, I can hear a clicking sound coming from the solenoid. I also verified that the power is coming from the car chassis battery, not the coach battery. This reference isn't of much help because it doesn't state what happens if there is no crank...

Also, I took the front cover off the switch board so that I could look behind the switch and I noticed that all three connectors were not connected to the switch. I reconnected them, but this did not fix anything. I've attached some pictures for your reference.

P.S. The LED light on my rocker switch doesn't turn on. I pressed the stop button three times within five seconds to see the error code and the light would not blink. Could this be indicative of something?

[chin_k]

Without having the genset circuit diagram or much experience with it, I am doing a armchair debugging here, so take it with a block of salt.

Sounds like the solenoid is working, and there is no voltage drop when the solenoid is ticking. So the next thing is to check the voltage on the solenoid output pin relative to the ground. When the positive battery connector is not connect to anything, the output pin on the solenoid should read zero, and when you jump the (+) battery connector to the start solenoid terminal, the pin should be 12V DC since it is how I expect the starter motor is controlled. If you see 12V, then measure the voltage on the starter motor. If there is 12 V there too, then you can try to jump start the starter motor directly (use a wire from the motor so that you can make the connection away from the motor, since when the starter motor work, the whole genset is going to jerk away, and it will be dangerous if your finger is nearby.) and see if it will go. It it does start, then it is something wrong on the wire between the solenoid and the motor. If it does not start at the motor, then maybe the starter motor got burnt out or seized. Check to see if it is safe to turn the motor shift by hand to check for seized motor, and make sure it is safe to do so without losing your finger, or damage your genset.

Again, make sure you keep away from moving parts and find the instruction on the service manual or call the Onan rep instead of trying to interpret a random advice online that was offered.

[tinyhouse]

You probable have checked this but check the grounding wire from the generator to where it connects on the frame. My solenoid would click but there was not enough current to spin the starter. Sometimes it worked , many times it didn't. Spent time tracing the positive wire from the battery to the generator looking for problems and didn't find any. I also had the correct voltage when I checked at the solenoid. I removed the ground wire from the frame, cleaned and bolted it back into place. No problem with the starter after.

[caconcourse]

Try running the engine while trying to start the generator. Since it is powered by the truck battery, there may be a voltage drop under load. Running the engine will allow the alternator to maintain high voltage.