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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 14436
Experience:  Certified on Onan and Generac generators
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My stand alone Generac generator will not start. It has spark

Customer Question

My stand alone Generac generator will not start. It has spark and I can smell the natural gas as it is cranking.
Submitted: 4 years ago.
Category: Small Engine
Expert:  Hank F. replied 4 years ago.

Thank you for choosing Just Answer for the solution to your problem.
My name is XXXXX XXXXX I am going to assist you with this.


What are the model and serial numbers of the genset?


Customer: replied 4 years ago.
Serial number:(NNN) NNN-NNNNbr/>Model (item) number(NNN) NNN-NNNNbr/>
Expert:  Hank F. replied 4 years ago.

First, the plug gap is way too wide at .035" - close it up to .020"


If that does not let the engine start, try this:

Remove the air cleaner.

Pour in about 2 teaspoons of gasoline (it will not hurt the engine).

Try to start it now.

Will it start on gasoline?


Customer: replied 4 years ago.
Ihave to go to work right now. I will try gaping the plugs at .020 , but, it says on the engine to gap at .040. I will try starting it with gasoline day after tommorrow and let you know if that works. Our your sure it won't hurt the engine since it runs on natural gas?

Expert:  Hank F. replied 4 years ago.

I am positive it won't hurt the engine - remember, the only difference between this engine running on gas, LP or NG is the carburetor, and different gap setting on the plugs.


I have never heard of a Generac running .040" on the plugs - that's REALLY wide.


The owner manual for your set specifies .020"


Let me know what happens.


Hank F. and 4 other Small Engine Specialists are ready to help you
Expert:  Hank F. replied 4 years ago.

I see that you have opened another question.


Please keep all correspondence to this question, and I will have the other question closed.


Do you have a multimeter to do some checking with?


Customer: replied 4 years ago.
Customer: replied 4 years ago.
what do I need to check with the multimeter?
Expert:  Hank F. replied 4 years ago.

Have you regapped the spark plugs to .020"?

If not, do that first,


If you have, remove the air cleaner.

Set the switch to "MANUAL".

While cranking, the choke plate should close for 2 seconds, then open for 2 seconds, and keep repeating until the engine starts.


Does the choke plate move like this?


Customer: replied 4 years ago.
It does not appear that the choke plate is closing and reopening by looking at the linkage assembly on the side of the carburator. The plugs were regappped to .020 and the engine did start when a teaspoon of gas was poured directly into the carb. It ran well, but when I tried to rerstat it it would not start on it's own.
Expert:  Hank F. replied 4 years ago.


You are going to need to test the choke.


First, see if you can manually move the choke linkage - it should move freely without sticking or binding.


If it does, disconnect the plug from the choke solenoid, and use your meter to check and see if you are getting 12V to the solenoid while the engine is cranking.


Customer: replied 4 years ago.
I cannot locate the choke solinoid, is it located under the air cleaner?
Expert:  Hank F. replied 4 years ago.

Yes, you can follow the choke linkage directly to it.


Customer: replied 4 years ago.
I can't seem to remove the bottom plastic piece below the air filter to be able to fully see the choke linkage and locate a wire off it to the choke solenoid. visualizing anything in that area is difficult.
Expert:  Hank F. replied 4 years ago.

You should not need to remove the air housing to access the plug.

You may need a small inspection mirror to see it, though.


Customer: replied 4 years ago.
I looked everywhere under the air housing with a flash light and a mirror but could not find any wires or solenoid. Is it possible it might be located somewhere else. Is there a place to futher back to measure the 12 volts 12 volts possibly the control card?
Expert:  Hank F. replied 4 years ago.

I'm a little confused here.

I went back to the book to double check the wire numbers.


I could not find the choke solenoid at all.

So I looked at a different book - and it clearly shows the choke solenoid as being there.

One book says this unit has a CS, and the other does not.


Does your set actually have a choke on it or not - or are you simply seeing the throttle plate?


Customer: replied 4 years ago.
Must be a throttle plate because I don't a choke solenoid anywhere or any wires at all and I looked over every inch with a flashlight and mirror. Coul it be controlled directly from the control panel?
Expert:  Hank F. replied 4 years ago.

If the choke would be controlled directly by the control board, but the throttle is a mechanical governor. It has nothing to do with the control board.


Have you had your gas pressure checked?


When was the last time this set had a valve check done on it?


Customer: replied 4 years ago.
Never had a valve check or a gas pressure check. It runs good when the carb is primed with gas though (smooth with steady idle). I agree that something must be going on with the choke. Back fires when I try to start it normally , do these engines require any kind of periodic timiing adustment?
Expert:  Hank F. replied 4 years ago.

There is no timing adjustment.

Timing is accomplished by the position of the magnet in the flywheel - which is cast in at the factory.


Your set may not have a choke on it - if you only see one butterfly, it is the throttle.


I would first check the valves - all should be set at .003"


If the valves are good, you need to have the gas pressure and secondary regulator checked.