Until recently, an always-dependable Onan, Model BFA, spec A, 3kw, mechanical ignition, w/260 hrs:

Started to stumble and got progessively worse. A look-see revealed severely pitted points.
Filed the points down and it ran like a Rolex for about 5-7 hours, then started to stumble again.

Installed new points/condenser/plugs/wires, double-checked gaps & connections. Again, it purred like
new, for about 10 hours, then beginnings of roughness. Inspection showed start of pitting on points again. Once more, points cleaned-up and it runs great, but I think it's a short term fix.....

What's the next logical suspect?.....I'm thinking coil, but then I really don't know what I'm doing either. This genny is 1950's technology - it ought to be something pretty simple

I would clean all the grounds, both associated with the points and genny to RV chassis. An intermittent energy surge do to bad ground could be one issue. Also, clean your float bowl, although not electrical the points pitting may be a red herring and it is fuel related. The ethanol gas of today is a real problem for these small engines that sit a lot.

Finally, did you say you checked the points gap?

Thanks Corey...I'll follow up on fuel system and double check groundings.....

Yep, point/plug settings are dead-on.....even opened up points a couple thousand
to see if that made a difference, but no noticeable changes.....

I'm still thinking coil, but since Onan apparantly makes the windings out of 18kt gold,
I'd like to follow through on less expensive scenarios first

quote:

I'm still thinking coil, but since Onan apparantly makes the windings out of 18kt gold,

Yes they certainly are "proud" of thier parts... A new fuel lift cost me $130.00...Good luck Lee...

Lee,

I agree that checking grounds and other connections are a good idea, along with the ignition coil as they can breakdown when hot. But don't discount another bad condenser. Even though you have changed it I've been blessed with several bad condensers in a row. All caused varying degrees of contact pitting.

Next time the genny starts to stumble shut it down and let it cool, then start it again. If it runs good I'd zero in on the coil as it's probably breaking down when hot. Another trick is to spray the ignition coil with freeze-it when the genny is stumbling. If it smooths out the coils is bad. good luck.

Roman

quote:

But don't discount another bad condenser. Even though you have changed it I've been blessed with several bad condensers in a row.

BINGO!.....It appears that replacing the new condenser with another new condenser has solved the problem...Apparantly, Onan feels that a new part doesn't necessarily mean it has to be a serviceable part

Thanks to all for your suggestions......I was able to avoid a home equity loan for a new coil...

On the road again, complete with microwave popcorn and 110v A/C....Life is good

I hope the new condenser makes it stay fixed.

The condenser does several things.

It speeds the collapse of the primary field, giving a stronger spark. A condenser failure could make a weak coil weaker. Many magnetos are very weak with an open condenser. Kettering ignitions less so, but it still happens. Perhaps you can find an old time auto parts store with a coil tester. Or you can cobble your own with a doorbell button, a condenser and an adjustable gap. A quick and dirty tester is a plug with a wide gap. Spark should jump a big gap and be purple, not orange. This is best viewed in the dark, or with a blanket blocking all light. (Don't do this where the neighbors can see.) I have seen test plugs sold. Just a wide gap plug with a ground clip or lead.

The condenser also absorbs countervoltage, avoiding a big spark across the points. This minimizes pitting. If there is a pyramid of metal on one contact and a corresponding pit on the other, the condenser is either under or over value. The pyramid on the arm means under and the pyramid on the ground means over. Or the other way around, I forget.

As has been mentioned, a coil can fail when warm. I once got home on a points MH by remotely mounting the coil up in the airstream ahead of the radiator. A condenser can also benefit from a remote location. You might move both just for experimentation. Every Lucas magneto I own gets its internal condenser removed and an external condenser, for example.

I have a capacitor tester that can test your condensers, if you wanna send them. Or I can send it to you for testing and purchasing condensers from an alternate source.

Often another, cheaper and available condenser is a good substitute and a candidate for external mounting. I don't own an Onan any more to test, and my Onan notes are long-lost on a crashed 086 computer.

Is your Onan a single or two cylinder? If it is a single cylinder, any good auto coil and condenser can be substituted. You will probably need a dropping resistor if a 12 volt coil is used. If it is a twin, an old (Kettering) Harley Davidson dual-fire coil can be used.