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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15264
Experience:  Certified on Onan and Generac generators
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I put a new solenoid into my generator, but since the fuel

Customer Question

I put a new solenoid into my generator, but since the fuel level was low, I had to prime the generator, it started, but backfired and solenoid blew. I tried it again with the old one solenoid, same result. I have filled the gas tank, so I won't be priming it again. However I hesitate to put another new solenoid in without some advice.

My question is: what is the likelyhood that the priming caused a problem for the solenoid, what could be other likely causes for the solenoid to immediatly go out, and what checks can I perform?
Submitted: 6 years ago.
Category: Small Engine
Expert:  Hank F. replied 6 years ago.

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My name is XXXXX XXXXX I am going to assist you with this.


Are you referring to the starter solenoid?


If so, priming has nothing to do with the solenoid.


Also, this set has no prime function.

How are you priming it?


Customer: replied 6 years ago.

Hi Hank,


Yes, it is the starter solenoid, and the priming was just because the gas tank was nearly empty and the fuel level did not allow fuel to reach the generator.


What could cause the solenoid to blow right after starting?

Expert:  Hank F. replied 6 years ago.

How did you prime the set? It has no prime function.

I need to know exactly what you did.


Also, what do you mean by the solenoid 'blew'?


Solenoids do not blow. They can burn out, but they do not blow.


Also, exactly how do you know that the solenoid has gone bad?

What tests/checks did you do?


Please be as specific as possible. Remember, I can not see what is going on, and I only know as much as you tell me.


Customer: replied 6 years ago.


I've been typing this for Ken - he's not available at the moment, but I'll get him to stand here while I type, and will answer your questions in detail on Tues. till then...

Expert:  Hank F. replied 6 years ago.

Not a problem.

It's just that the more detail I get, the better I will be able to help.


Customer: replied 6 years ago.

Ok Hank, Here we go. (I'm typing for Ken)

When a new starter didn't do the trick, the solenoid was his next guess. He put a new one in, then primed the carbeurator (gas tank was too low), and the generator (w/ new starter and solenoid) did start. Immediately after, there was a metalic "clank" sound from the solenoid, and then just clicking - engine wouldn't keep running.

He tried the old solenoid - same result. There was a type of "backfire" and the solenoid failed- that's what he meant by the solenoid blowing.


Ken would like to explore/test before ruining another solenoid. What are your suggestions?

Expert:  Hank F. replied 6 years ago.

1. Exactly how was the carburetor 'primed'?


2. There is nothing in a solenoid that can make a 'clank' sound. I do not believe the solenoid is the problem.


3. This clicking - is it a single click as you press and release the start button, or is it a continuous rapid clicking as the start button is held?


4. I would like this check done. At the far right end of the genset, directly in the center, is a 3/8" Allen bolt. Remove the spark plug wires, and use an Allen wrench, and turn the genset over several times (8 or 10). It should turn over very easily. Does it?

Is there any sticking or binding noted anywhere in the revolutions?

Are there any unusual noises (you should not hear anything).


Customer: replied 6 years ago.

1. The carburetor was primed by removing the air filter and spraying starter fluid into it, then hitting the switch, the engine started.


3. The clicking was a continous rapid clicking from the solenoid as the start button was held down.


4. The engine revolves normally, it is not seized up, no sticking or binding. Of course after the solenoid fails, the starter does not turn the engine

No other unusual noises.



Expert:  Hank F. replied 6 years ago.

Number 3 - the continuous rapid clicking is an indicator that not enough battery voltage is getting to the solenoid. I would bet that the 'clunk' you are hearing is the bendix engaging the flywheel, but not having enough energy to crank the engine.


First, check all battery cables to make sure the connections are clean and tight. Pay special attention to the ground cable between the genset and the frame of the coach.


If the cables are good, take the battery in and have it load tested.


Do not rely on a voltmeter or battery charger to tell you if the battery is good or not. Even a bad battery can read fully charged with 12V.


If it turns out to not be the cables or battery, please let me know.


Hank F. and other Small Engine Specialists are ready to help you
Expert:  Hank F. replied 6 years ago.

The starter does work and turns the engine initially, so I think the problem is not the battery. Another thought - maybe when I hooked it up, the wire numbered "6" from the switch panel to the solenoid isn't correct. the schematic seems to show a connection to the solenoid on the battery side of the solenoid. Should the #6 wire go to the starter motor side of the solenoid.


Optional Information:
Make: Onan
Model: NHE GenSet


If you are referring to the wire numbered J1-6, then no - it must go to the battery side of the solenoid - it is what supplies control power to the control board.


I still highly suspect a bad battery.

Take it in and have it load tested.


Let me know how it tests out.


Customer: replied 6 years ago.



Thank you about the wire info, it is hooked up correctly. Ken says the battery is definitly good since it starts the motor home (drove it just last night) and it did turn over the generator. what would be next?

Expert:  Hank F. replied 6 years ago.

Are you sure the genset is connected to the chassis battery, and not the house batteries?


Most often, the genset is connected to the house batteries, to prevent the genset from draining the coach battery.


Next would be to measure the voltage at the starter solenoid, both while sitting still, and with the genset engine cranking.


What are these 2 voltages?


Customer: replied 6 years ago.

Hey Hank,


He got it running!! runs well ( a little rough), but is leaking a little fuel - easy fix,

so I think we're set! Thanks for all your advice!


Ken and Lynne Hamilton

Expert:  Hank F. replied 6 years ago.

No problem.


So it was a bad battery?