Saturday, October 20, 2012

Generators – Trouble Shooting

It's easy to take your generator for granted - all you have to do is push a button and presto, you have 110 V AC power. But then once in a while, it's not quite so "presto". You push the button and you're not rewarded by the sound of the genset operating.

The first thing to remember is that generators do better when used more often. It is highly recommended that you "exercise" the genset at least once a month for an hour under at least half load. This helps prevent the carburetor from getting gummed up.

There are two sections in this article - The generator will not start and the generator starts, but produces no power.

Generator Will Not Start

Starting in 2002, the Onan MicroQuiet replaced the Onan Emerald Plus. The Microquiet has a prime function on the Start/Stop switch on the range hood. This feature was not documented in the LD Owner’s Manual until 2007.

1. Before starting, hold the switch in the STOP (down) position until the green light comes on. You may hear a faint rattling noise as the fuel pump pulls gasoline from the tank.

2. Release the button when the green light comes on, and press and hold the switch in the START (up) position until the generator catches, then release it.


If the button is pushed and there's no cranking or starting noises - - suspect a dead battery or loose/corroded connections.

If the button is pushed and there's only a clicking noise - - low battery, loose connections, or faulty starter solenoid (relay or contactor - same thing).

If the button is pushed and the engine cranks normally but doesn't start - - low or no fuel reaching the engine, faulty ignition system, low oil cut-off, gummed up carb, etc.

If it has a little vibration or hesitation: Try cleaning the spark arrestor. This is a plug that is in the muffler-like exhaust under the units, Its not the regular muffler but one that is under the unit. Some have one plug some have two. Unscrew the plug and start the unit, let it run for 15 minutes, shut off and re-install the plug.

The plug may be difficult to remove. Heating it should help break it loose. If you want to try penetrating oil, PB blaster is highly recommended; it's a penetrating catalyst and a magnetic lubricant.

Refer to the Onan Owner's Manual for deciphering the trouble codes that the generator displays.

Try the start switch on the front of the generator - if it starts there, the start switch/wiring is the culprit. If it does not then the battery feed to it could be one issue. Can you measure 12 volts at the gen from the line(s) that comes to the battery? It is a large wire that comes up from the lower right corner of the gen box. Connects to a large stud on the start panel.

Check the circuit breakers. They are self resetting but can go bad. You can check to see if they have 12 volts on each side of the lugs. I think LD runs 2 lines over the gen to get the right staring current applied the gen. If you only get 12v on one side of the switch (s) then the switch(s) is bad. If you don't measure 12volts on each side of the switch, then the line(s) between there and the battery need to be looked into. They should be connected to the battery.

Are your house batteries fully charged? Are the battery connections clean and tight?

There is a small possibility you have lost ground to the gen box or the gen itself. There is a braided ground strap near the base-plate mid gen. You would probably have to take the gen out to get a good look at it on yours. You could always check continuity from a bolt on the gen case to the mounting plate to see if the ground strap still works.

Contributors: bumper, oldtrucker63, Ramon

Revised 1 Jul 11

Generator Starts, but no Power

Generators are wonderful things to have sometimes.....when they work. In a previous LDC article we discussed generators that won't start. We go a step further in this article and present some trouble-shooting tips for a generator that starts and runs, but is not putting out any electric power.

- Check all the electrical breakers. Not only are there breakers inside the front cover to the converter/charger, there is also a breaker located on the generator. Turn it all the way off and then back on. If the microwave and/or AC were turned on when you started the generator, the load may have been too much and tripped that breaker. It's better to ensure all power-hungry appliances are turned off before starting the generator.

- There is an Automatic Transfer Switch that switches the rig's 120V source between generator and CG power. Verify that yours is working.

- Do you have a "whole house" surge protector? There is usually a delay of a couple of minutes before it will allow power through it.



First, make sure that the switch on the side of the generator has not opened. Your manual will show you where it is. Assuming that the switch is closed, the next question is what is the status of the breakers in your service panel. Try to reset the main breaker. Still no power? If not, (and this was my issue, solved with Andy's help) you may have a bad Automatic Transfer Switch. The ATS is located behind, and attached to, the main breaker box. Replacement can be a real headache, but that is the only way to deal with a bad ATS.

Unless you are pretty comfortable working on equipment, including 110v power systems, replacement is best done by a service person. Assuming you are comfortable here are the steps:

1) Remove the front of the service panel and cut all power - shore, solar, and batteries.

2) Using a multimeter, verify that everything in the panel is dead - no voltage anywhere.

3) Unscrew the four screws that hold the panel in place and slide it out until you can see the back.

4) The metal box on the back is the ATS. On the very back near the bottom of the ATS is a screw. Remove that screw.

5) The back and top of the ATS will now slide up, exposing the ATS connections.

CAUTION - steps 6 to 10 involve checking voltages on live, exposed circuits. DO NOT TRY THIS UNLESS YOU KNOW WHAT YOU ARE DOING!!!

6) Turn on the generator.

7) Screws 1 and 6 are for the power from the ATS to the panel. Screws 2 and 5 are from the generator to the ATS. Screws 3 and 4 are from shore power to the ATS. Check voltage between 2 and 5.

8) If there is no voltage, or if significantly other than 110v, you have either a generator problem or a wiring problem from the generator to the ATS.

9) If there is 110v between 2 and 5, check the voltage between 1 and 6. If you read no voltage you have a bad ATS.

10) Turn off the generator and put everything back together.

11) If the ATS is bad, order a new one and install it when it arrives.

12) If the ATS is not the problem, and your generator is not delivering voltage to the ATS, and the breaker switch on the generator is closed, you need a generator service person.

Contributors: Alex Rutchka, Doc, JC, Ken F


This helpful link is to an external site. If you find the link does not work, please notify one of The Companion authors.

RV Generator Operating Tips

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