Onan generator won’t start

[Piros1]

Originally Posted by texaslime

You might try unplugging 1 switch at a time to see if it will shut off. You may have 1 of your 4 switches shorted not letting it to shut off. Just a thought.

Thanks, I will try that.

[hypoxia]

You haven't stated the model number??? Did I miss that?

Have you looked at the Onan Service Manual in the troubleshooting section?

My HDKCB 12.5 Service manual, the very first troubleshooting item is "No Response at Control Switch". That's where I would start.

[cimplexsound]

If it doesn't work it's likely you have a dead battery or the ground to the battery is bad. Your generator starter works of the ground from your RVs body. Also check your remote switch wiring where it plugs into the generator to make sure you don't have any corroded, 🔌💡loose or bad wiring.


1979 Dodge Tioga Class C 24 foot. 1987 Fleetwood Bounder 34 Foot.

[Piros1]

Originally Posted by hypoxia

You haven't stated the model number??? Did I miss that?

Have you looked at the Onan Service Manual in the troubleshooting section?

My HDKCB 12.5 Service manual, the very first troubleshooting item is "No Response at Control Switch". That's where I would start.

I did not as I didn’t have it at the time of the post. Also did not get an owners manual with the post. I did read online how to check codes and there are no codes stored. It does have a code after I disconnect the fuel to shut down but once restarted the code clears until you shut down. The code is due to having to disconnect the fuel solenoid to shut it down. After shutdown you can rock the switch off and on once and it clears. I’m on my way home at this point so when I get there I will do some more research. Most likely since I have figured out how to get it to clear and restart it will be something simple. I haven’t needed it on this trip much so good for now.

[Piros1]

Originally Posted by cimplexsound

If it doesn't work it's likely you have a dead battery or the ground to the battery is bad. Your generator starter works of the ground from your RVs body. Also check your remote switch wiring where it plugs into the generator to make sure you don't have any corroded, [emoji366][emoji362]loose or bad wiring.


1979 Dodge Tioga Class C 24 foot. 1987 Fleetwood Bounder 34 Foot.

I checked all the obvious things first before posting. It will start once I clear the code from the hard shut down. (Disconnecting the fuel solenoid.) Besides I have power to it and my coach and chassis batteries are all working properly and fully charged. Everything else in the coach is working as it should with or without shore power. Checked all connections going to the generator and all connections I can see in the generator without pulling the generator out of the coach. That will be a major operation if I have to do that.

[Piros1]

Originally Posted by hypoxia

You haven't stated the model number??? Did I miss that?

Have you looked at the Onan Service Manual in the troubleshooting section?

My HDKCB 12.5 Service manual, the very first troubleshooting item is "No Response at Control Switch". That's where I would start.

For what it is worth my model number is 12.5HDCAB11506D.

[Rkesselus]

Originally Posted by Rkesselus

When you disconnected the fuel solenoid you may have caused a loss prime situation. Listen to the fuel pump and try to determine if it is pushing fuel against pressure. If not you might try replacing the fuel filter, after filling it with fuel, then listening to see if the fuel pump picks up a load. It does not take much to keep the fuel from being delivered to the injectors.

I did not read the part about no shut down. To stop a diesel engine you must remove either the air source or the fuel source. So what you are doing to stop it by disconnecting the solenoid is what should be happening any way\, removing power to the pump. Now suspect that the solenoid if faulty.

[Piros1]

Originally Posted by Rkesselus

I did not read the part about no shut down. To stop a diesel engine you must remove either the air source or the fuel source. So what you are doing to stop it by disconnecting the solenoid is what should be happening any way\, removing power to the pump. Now suspect that the solenoid if faulty.

Tat is a thought, that didn’t even cross my mind but you could be correct. I am home as of this past Sunday and back to work today. Not retired full time yet but working on it. I have a to do list for the coach and this is part of the list. I get a break in the weather I plan to start on the list, when I get t figured out or have more questions I will post my results. May help someone else down the road.
Thanks

[THenne1713]

Many/ Most KILL switches on GENs w/ Magneto simple short the points/ ignition to ground; on electric powered IGN, it simply turns OFF the 12v power to IGN and Fuel Pump; so you either have a failed ground, or a shorted power switch that won't turn OFF.

[Rkesselus]

Originally Posted by Piros1

Tat is a thought, that didn’t even cross my mind but you could be correct. I am home as of this past Sunday and back to work today. Not retired full time yet but working on it. I have a to do list for the coach and this is part of the list. I get a break in the weather I plan to start on the list, when I get t figured out or have more questions I will post my results. May help someone else down the road.
Thanks

aFTER READING ALL THE OTHER POST IT OCCURED TO ME THAT YOU UNIT MAY NOT BE DIESEL. tHE SIZE 12.5 MADE ME ASSUME THAT IT WAS DIESEL. iF IT IS GASOLINE THEN FORGET ALL I POSTED. gOOD lUCK rICHARD. As one said to assume is to make an ass out of you and me. and it looks like I must have hit the caps lock key.

[Piros1]

You were correct, my generator is a diesel. My mechanic and I were discussing it today as well. Haven’t done any additional diagnostics just yet but plan to. Pretty much it is correct that cutting off the fuel or air typically will shutdown any internal combustion engine. Gas or diesel both require fuel and air. A diesel just doesn’t require an electric spark to ignite the fuel, it happens by heat generated by compression of the fuel air mixture. I have the basics down just don’t have the knowledge of what may be controlling the system to shutdown. My thoughts are a control board that may be hidden somewhere or a relay that is shorted. Will see.

[DENSHER]

The fuel solenoid is ON with voltage to a magnetic coil and spring returned to OFF when voltage removed (switch off). In this case of not turning off until solenoid is unplugged would indicate voltage is still present at the coil, it will spring to off with wire disconnected shows that solenoid is not sticking because the spring returns it to OFF.
Most fuel solenoids have 2 wires going to it. 1 Wire is for high amperage to pull the solenoid into the ON position the second wire is lower amp feed to retain the magnetic field without overheating the coil.
After unplugging the solenoid to kill the engine check for voltage is the wires then trace wire back until you find the source of power.

[Piros1]

Originally Posted by DENSHER

The fuel solenoid is ON with voltage to a magnetic coil and spring returned to OFF when voltage removed (switch off). In this case of not turning off until solenoid is unplugged would indicate voltage is still present at the coil, it will spring to off with wire disconnected shows that solenoid is not sticking because the spring returns it to OFF.
Most fuel solenoids have 2 wires going to it. 1 Wire is for high amperage to pull the solenoid into the ON position the second wire is lower amp feed to retain the magnetic field without overheating the coil.
After unplugging the solenoid to kill the engine check for voltage is the wires then trace wire back until you find the source of power.

Thanks, that makes sense. I will check tomorrow weather permitting.