1989 Onan Generator ingnition coil question

So last night i wired up a 12 v light bulb to test the Coil. I went out side this morning to test the coil and after a few cranks I got a pop, hmm. So i put my fuel line in the gas can and she fired up. Its running very rough surging with the lever going back and forth. could that be my carburetor gunked up? Also, when I remove my connection from the car battery, the gen dies, is that to be expected?
I am guessing cleaning the points made a difference, thats actually what I planned to do today, take them off, clean them up and set the gap. Not sure if I should touch them now.
Any other ideas on the surging?

Thanks for all of the help

Here's a Battery/Coil/Points/Condenser Ignition.
With Points Open and Condenser disconnected, you should see Battery Voltage on both sides of the Coil.
When Points CLOSE, a Magnetic Field forms in the Coil.
Spark Occurs when Points OPEN and the Magnetic Field suddenly collapses.
You can see from the Diagram that if the Condenser has failed Shorted, it will be as if the Points never Open.
I can't tell you the electronic theory, but I understand that if the Condenser is failed Open (not charging when the Points Open, as if it wasn't even there), the Magnetic Field will not collapse quickly enough to cause an adequate Spark. Perhaps no Spark at all.

From what I've seen, many of the "Safeties" on a genset are bypassed when it's cranking. If it fires up, then quits as soon as you release the switch from Start, then it's possible a Safety like Oil Pressure or Power Output isn't being satisfied. Our BFA, for example, used House Battery Voltage to Crank, Provide Ignition, and run Fuel Pump when the switch was in Start. Once it started and I released the switch to Run, it provided its own 12VDC for Fuel, Ignition, and recharging the Battery. If it didn't produce 12VDC it'd stop. Oil Pressure Switch was also bypassed.

Check your Service Manual. Find the Wiring Diagram. I think you'll find that the "Switch" in the diagram above is actually a multi-contact switch and/or the output of a Relay or two.

I'm gonna guess that you have a control inside the Coach as well as on the Genset itself. Sometimes problems arise with the inside control and/or the wiring and connections to the Genset. Try disconnecting the inside control.

ok, so i picked up new plugs, didn't fix it. I do have voltage at the points when I press the start button but I am not seeing any spark at the points.
I have tried unplugging the oil sensor, leaving it open and also grounding it, no difference.

So I do not have any old condensers laying around, can i get one from sears or an auto parts store, tractor supply? Any ideas on what to get?

I also used some emery cloth on the points. Will a bad condenser prevent the points from sparking?

Jeffery,

A condenser (capacitor) (small silver container) of that age could be your problem.
Almost all point/capacitor ignition systems use a .23mf condenser. So any condenser from a point ignition system that you can fit in will work. Surely you have an old condenser from a 1949 chevy on the shelf? GRIN.

Richard

I also tried measuring the voltage on the coil during start and I get 12 volts(actually only about 9) on both the + and - terminals. Does the coil sound bad to you?

Before you go tearing everything apart and move from one electrical component to another, I would suggest you check the most obvious things, first. I know the generator has a couple of auto-shut down features and those should be checked. Check the oil level, for one, they are very snotty about that, especially if the rig is off level.

You want good 12v voltage, not 9v. Jumper a battery to a terminal of the generator so it gets full 12V. If you have the cover off the ignition points set, turn the engine over. you should see spark. If not, follow the troubleshooting guide.

You need a flat feeler gauge. If that's what you use on plugs it'll work. There's a round ramp-like gauge that works on plugs that definitely will not work on points. For starters just try cleaning them first and making sure they at least close and open. I changed points on our old BFA and not sure I really needed to.

Thanks JD I will try this list. I was at the auto parts store guess I should have got some plugs. I will also need some type of gap tool to set the points. I assume I can just use a spark plug gap tool?

The screw in the white plastic on the left must be a connection terminal. The screw on the right with the spring under it is the point gap adjustment. The black screw holds the points assembly in place on the engine block. The points usually work off of a little cam, but you can't see it on the ONAN because the cam is internal and a little push pin pokes out to open the points.
I think I'd do this:
1. Check to make sure there's voltage at the points with the engine not running, switch to Start, and Points open as in the picture. If there's voltage
2. Clean the Points very gently with an emery board, piece of fine sandpaper, or an ignition or jeweler's file. Check the gap and adjust. Crank and see if it starts.
3. If it doesn't, Clean or Replace Both Spark Plugs. As Chris says, either plug fouled/shorted and neither will fire.
4. If it still doesn't run, test or replace the Ignition Capacitor. Any ignition capacitor that you can mount will work. You can "kick test" ignition capacitors with an old-school analog (with a needle pointer) meter.
Do you by chance have another coil? Even if it's got only one high tension socket, it should throw spark if the rest of the system is working. That'd give you an idea if your ONAN coil is good or bad. Just wire it up to one plug.
I once tried wiring both plugs to an ordinary automotive coil with one terminal. It did NOT work...

At this point, you can

Keep in mind that is a "wasted spark" type system, it fires both plugs at the same time, so if either plug or wire is bad, no spark, as the completed circuit goes through both. That's also why the plug gap is only .025.

my model is 4.0BGE 1R/26100f