Small Engine Problems? Ask an Engine Mechanic for Answers ASAP
There is a very good chance that the field simply needs to be flashed.
1. Remove the spark plug wire.
2. Obtain an old extension cord that you can cut one end off, or an old power cord from an appliance (you will need the male end left on the cord).
3. Note how on the receptacle, one slot is longer than the other. This longer slot is the negative slot. It is critical that you get it hooked up correctly.
4. Determine which wire of the cord will go to the negative slot.
5. Connect the negative wire to the negative terminal of a 12V battery.
6. Connect the positive wire to the positive terminal of the battery.
7. Plug the cord into the receptacle and pull the starter cord 6-8 times.
8. Immediately unplug the cord. DO NOT LEAVE THE CORD PLUGGED IN FOR MORE THAN 6 OR 8 SECONDS.
9. Disconnect the wires from the battery.
10. Reconnect the spark plug wire and see if the set is now producing electricity.
If it is not, please let me know and we can troubleshoot further.
Is this an EX4500, or an EX4500S?
What is the serial number?
My generator does not have a starter cord. Can I use the strarter key switch instead.
I understand from your procedure that I have to hook a 12 volt battery to any of the 110 volt outlets on the generator. Is this correct?
Do I set the main breaker on or of?
Somehow this just doesn't seem logical.
I agree, it does not seem logical.
But the physics behind it are this:
The rotor (you may call it the armature), retains a small amount of magnetism (residual magnetism) to initiate the power generation process. If the rotor is damaged by hitting it or dropping it, it can lose this residual magnetism. The magnetism can also dissipate by itself over time if the set is not run.
Flashing the set can restore this residual magnetism.
It does this by sending a DC current through the AC windings (yes, you put 12V battery through the AC receptacle), and turning the stator (the outer windings), into a magnet. By spinning the rotor, it can transfer some of this magnetism from the stator to the rotor. It does not take much.
The circuit breaker must be on to allow the voltage to get to the windings.
Make sure the spark plugs are disconnected - you do not want the engine to start.
With an electric starter, about 3-4 seconds should do it.
And, as I stated, if this does not work, let me know. We can do some detailed troubleshooting from there.
Hooking it to the 12V connectors will not work. These connectors get their power from the AC windings of the stator. The AC power goes through a series of diodes, which are one way valves for the electricity. It can flow out, but not in.
If you disconnect the spark plug wires so the engine can not start, it will not produce 120V. I have done this many times.
If you are still unsure, simply place a 10A fuse on each wire. Any AC ripple that might be there will blow the fuse.
I tried your recomendation yesterday and it did not work. I made sure that the negative pole on the battery went to the side of the A/C outlet that is shaped like T. Also made sure that the breaker was on the on possition. And cranked the starter for a few seconds. The generator still does not produce power. Keep in mind I have a voltmeter, in case you want me to run other tests. I alsdo have the cover on the side of the generator open for easy access to the generator side of the unit.
I am surry if I sounded rude not trusting youre recomendation. As an engineer I need to know the reasoning of things.
I did not take it as you trying to be rude - I took it as someone who had enough common sense to question something that defies common logic. Plugging DC into an AC circuit seems like an accident waiting to happen - and it is, unless done in a controlled manner, under the proper circumstances.
Flashing the field did not work, so now we are down to actually testing the circuits involved.
Inside the end panel of the generator, locate the brush block. It will have a red and a white wire attached to it. Pay attention to which wire is connected to which brush and disconnect both wires.
Set your meter to ohms and connect one lead to each brush. What is the resistance of the field winding?
Reconnect the wires to the brushes.
Set your meter to VDC and connect the leads to the wires. Red is positive, white is negative.
Crank the set over and note the voltage.
How much voltage is available to the brushes?
No, I am also on EST.
No problem on the time.
I work from 3-11, so will not be able to respond until about 11:30 tonight.
Once we get these results, there should not be more than 2 or 3 other tests we need to do - and they can all be done at once.
But right now, I need to know the resistance and voltage to know where to go next - into the stator and rotor, or into the AVR.
The voltage is awful low, and the resistance seems a little high.
Remove the brush block and inspect the brushes. They should be worn into an even arch pattern, and should not be chipped or cracked. They should slide freely into and out of the block.
If they stick or bind, clean the block with electrical contact cleaner.
Now inspect the slip rings. They are the 2 metal bands that the brushes ride against.
They are made of copper, and should resemble shiny copper. They should not be pitted or scratched.
If they are dirty, you can clean them by attaching a piece of scotch brite or 400 grit sandpaper to the end of a small wooden stick.
Start the engine and press the scotch brite to the rings for a few seconds.
Once they are clean, ohm across the slip rings. As best as I recall, the resistance should be in the 30-50 ohm range.
Disconnect the wires from the brushes.
Make up 2 jumper wires that will connect to the brushes.
Connect one jumper to the brush that had the red wire, and the other end to the positive post of a 12V battery.
Connect the other jumper to the other brush.
Start the engine.
Connect the loose end of the second jumper to the negative terminal of the battery.
Measure the voltage at the receptacle.
If it is at least 50-60 volts, your voltage regulator is bad.
Let me know what happens.
I almost missed this one, as I do not always read my feedback. Thanks for the positive feedback, by the way!
You had stated in your initial question that the engine was surging (speeding up and slowing down), but you said you had it fixes, which is why I did not dwell on it.
If it is still surging, the problem is in the carburetor.
As gas gets old, it turns to varnish and clogs up the passageways inside the carburetor, not allowing enough gas to get to the engine.
When this happens, either the engine simply will not start, or it will not run without the choke on (this reduces the amount of air getting pulled into the engine, changing the fuel/air mixture), or it will run but surges.
Another issue that varnish in the carb can cause is that the varnish may not allow the float needle to seal properly against the seat, causing the flow of gas to not shut off when the bowl is full. The result will be gas overflowing the carb and running into the cylinder, and possibly out the air intake. If the gas gets into the cylinder, it will seep past the rings and down into the crankcase. This will be evidenced by your oil level being over-full and/or the oil smelling like gas.
The only 2 solutions are to either replace the carburetor or give it a good, thorough cleaning.
To clean the carb, you must remove it, disassemble it (making sure to remove all non-metal parts), and soak it in a commercial solvent for several hours. Soaking it overnight is even better.
Then clean all solvent off with a spray type carb cleaner, making sure to get lots of cleaner into every hole and passage there is. Pay special attention to the tiny holes in the bore of the carb, under the throttle plate for the carbs that have these holes. Use lots of cleaner. And make sure to wear safety goggles to avoid getting the over spray into your eyes. There will be over spray.
Dry the carb with low pressure compressed air.
When reassembling the carb, make sure to use a carb kit, when one is available for your carb.
Occasionally, even a good cleaning is not going to be sufficient, and you may end up having to replace the carb anyhow. Be prepared for this.
If for some odd reason this does not help, please let me know so I can assist you further.