Onan 4.0 BFA generator problem

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ditrranch

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Jul 22, 2011
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have a onan generator from a '79 mh. just bought it less than a week. guy told us that the starter solenoid was bad so i replaced it. the two deep cycles batts were disconnected so i started charging them and hooked them back up. the solenoid started making a clicking sound as soon as i connected them. disconnected the batts. they're still charging.
what is causing the clicking in the solenoid & what do I do to fix it?
thanks,
John
 
If the clicking noise started immediately when the batteries were connected, then I would suspect a bad starter switch or crossed wires somewhere between the generator and remote start switch (if equipped).

I'm thinking that the generator was attempting to start but had insufficient power to turn the generator over.

Joe
 
Agree with Joe. If you have a remote switch on the dash, you might try unplugging the remote switch wire harness at the genset, then see if you still have the issue. If you don't have a remote start switch, then there is an issue with the switch on the generator itself or the wiring or circuit board that it's wired to.
 
I have the same generator and when the battery is low it clicks instead of starts. What I do is run the engine for a few minutes and then start the gen with the engine running. Once the gen has started you can turn off the engine and let the gen run for a few hours to recharge the batteries.
 
just so were clear. i don't even push the starter button. i just connect the batteries and the clicking starts. i don't even get around to pushing the starter button. same answers apply?
thanks,
John
 
Are you sure it is the generators starter solenoid???. If it were me, I would get help and determine EXACTLY what is clicking. There are a few solenoids or relays in  motor homes that could cause the clicking sound you heard.
 
ditrranch said:
have a onan generator from a '79 mh. just bought it less than a week. thanks,
John
Click to expand...

Is this generator in a motorhome or just a generator you bought to install in a motorhome?
 
Good catch Waterdog!!!

If Waterdog is right about a possible new install (or hooking it up while still sitting on the ground), I would start looking very carefully at the manner in which you are hooking it up. Something strange going on here!!!! The starter solenoid normally has no power to it except through the start button when operated.

(If not installed, I hope it is at least fastened down solidly or you may get a big surprise should it suddenly decide to start....)
 
it is installed in the motorhome. as far as i can tell, probably the original generator. the way i understand a starter solenoid, in a car, battery side of solenoid has constant power. starter side of solenoid only gets power when the switch is energized.
the clicking is coming from the solenoid. you can even feel it when you touch it.
it might be the remote starter switch. is blinks with the clicking. is there a way to test to see if the switch is bad or do you just have to replace it and see.
greatly appreciate everyone's input.

John
 
You shouldn't have 12 volts at the "S" terminal (small one) at the solenoid until you hit the start button....same as a car. If you do, the voltage is either coming through a faulty start button, it is wired wrong, or in the case of a circuit board mounted start button (which you probably don't have) could be bridged there. Does your solenoid look like the picture below?

The other important thing on Onan generator solenoids, is be sure you only use one that is Onan...don't try using a Ford solenoid as Onans have an additional wire connection built inside....but that shouldn't have anything to do with your particular problem.
 

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I would try disconnecting the two small wires from the solenoid. If the clicking continues then you have a bad solenoid. If it stops then the solenoid is not the problem and you should look elsewhere. Are you sure the coach batteries plus and minus are hooked up properly?
 
Just disconnect one of the small wires at the solenoid. The clicking should stop. Replace it and do the same behind the switch, one wire at a time. Something is feeding that solenoid winding (the small wires) and it should not be unless the starter button is pressed. You could well have a defective start button. (i.e stuck/welded contacts within the switch) and that can be proven by testing as described.

The fact that the starter does not turn over may be a good thing at this point but you will probably have a somewhat discharged battery to look into later.
 
ditrranch said:
it might be the remote starter switch. is blinks with the clicking. is there a way to test to see if the switch is bad or do you just have to replace it and see.
Click to expand...

As mentioned before, unhook the remote switch wire harness at the generator, then hook the battery back up and see if the probelm is eliminated. If that eliminates the clicking, then it is a problem with the remote switch or a short in the switch wire harness. The harness on my Onan Emeral Plus (BGE) plugs in on the right side of the control box and has about 4 wires in it (for the start switch and hour meter), not really sure if it is in the same place on yours.
 
Stray thought to the others here...

John stated that the previous owner mentioned the start solenoid was bad, and left the batteries disconnected.

What if the previous owner had it apart and hooked the wires up backwards? (Solenoid backwards, so the 12V feed was on the outgoing side of the solenoid, start circuit connected to the tab that supplies 12V to the run circuit...) On mine, it would not be impossible to do and I don't imagine the results would  make the solenoid very happy regardless of the battery condition.

 
Here is a link to an online service manual. It has a great troubleshooting section:

http://asavage.dyndns.org/Onan/display1.php?Path=900-0337&db=Onan&table=900_0337&Page=front
 
Water Dog said:
You shouldn't have 12 volts at the "S" terminal (small one) at the solenoid until you hit the start button....same as a car.
Click to expand...

I may be wrong about this, I found one diagram for an Onan BGE that shows 12 volts at the "S" terminal and the start switch completes the circuit to ground.
 
Looks like Water Dog has come through again!!! It seems the start circuit is no where near that of a car, it is much more complex using a series of relays and their contacts for logic/control and uses windings in the generator itself to crank the engine. The manual shown by Seilerbird has the diagram and circuit description on P.38

I would have to study and understand that better to offer any further advise but I strongly suspect mis-wiring or something similar by the original owner or OP (yet).

Interesting concept!!!
 
I think it would be helpful to have the complete model # ditrranch. The manual that seilerbird referenced and as Stu correctly pointed out, says that this model uses the generator as a motor to start the engine. What I'm not sure about is if your model fits the BFA (Spec A-C) category.
 
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