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Onan CCKB intermittent spark

phrankndonna

Registered
Hi again,

We've got an Onan CCKB 2 cylinder air cooled gasoline generator that came out of a 1967 motor home. It has VERY few hours on it. We cleaned it up, heads cleaned, carburetor rebuilt, new fuel pump, and it almost runs. We find ourselves with an intermittent spark. When the spark works for about 5 seconds, the motor purrs like it just came off the assembly line (amazing after all these years of just sitting!). Then it quits, and we check, and no spark. We have new spark plugs and a new condenser. After a few minutes of waiting, we try again, and we have spark for a few seconds and it runs. Then it quits again. I'm wondering if it might be the coil, or we've traced the wires to possibly the low oil pressure switch. We just are not sure. Any thoughts? Thanks!

Frank
 

lokay5

Registered
Last Subscription Date
01/11/2015
It sounds very much like a bad condenser. I know it's new, but "new" doesn't necessarily mean "good".

Re
Bad new condenser

See post #16 under "Just about to give up on NH..."
 

phrankndonna

Registered
Thanks! I'll replace the points. And as for the bad condenser, I remember working on 70's era cars and replacing the points, plugs and condenser, and every now and again getting a bad condenser. It sure goes against the grain of what should happen, but you are right, it does. Thanks for the replies!

By the way, any idea of where best to get points and condenser for this generator? Thanks again!

Frank
 

phrankndonna

Registered
Hi, the points plunger is indeed moving freely. It simply will spark for a short period, and then just stop. Once we wait a few minutes and try again, it sparks and starts for about 10 seconds, then the spark gives out.

Any idea where to get points and condenser (or any other parts) for this Onan CCKB? Thanks!
 

Ed Sparks

In Memory Of
Last Subscription Date
06/28/2015
onanparts.com[ A sponsor here at the stak}] searspartsdirect.com,
or if your lucky and have a real old time parts store with a counter guy that knows how to read the books. We have a carquest store here with a bunch of oldtimers that can find just about anything.
 

Pete Spaco

Registered
I don't know CCK's all that well, but assuming that it has "battery" ignition, as opposed to a magneto, think about this:

One can "halve the circuit" as we used to say, by learning whether the spark is going away because of the points circuit failing to switch or because the ignition system is loosing its power input.
Get a multimeter, if you don't already have one. Set it to read DC volts and connect the negative lead to battery ground and the positive lead to the coil plus side (not the side that goes to the points).
Now have someone read the meter as you start the engine. The voltage should read between somewhere in the vacinity of about 6 volts to 12 volts or more as the engine starts. (I'm not sure if this model has a series coil resistor or not).
Anyway, as long as the engine is running, you should see this voltage. As soon as the engine quits firing or starts to sputter, see what that voltage is doing. If it all goes away, then the problem is someplace in the control circuit, but if it remains as the engine slows down, then it probably does have something to do with the points, condenser or whatever is connected to the other side of the coil.

Others, please chime in if this doesn't sound right.

Pete Stanaitis
-------------
 

Dave Edmonds

Registered
Last Subscription Date
01/27/2014
The voltage you're reading in the above instance is a pulsed voltage (points opening and closing as the engine runs); analog meters will give you a fairly consistent reading when the engine is running, no tellin' what a digital meter might read under those circumstances. However, when the engine quits, either meter should provide the information Pete supplied above. A test light can also be used in this instance, because you're looking for the presence or absence of voltage when the engine quits.
Dave Edmonds
 

Flintstone

Registered
Also one easy thing, I think. My points box has a wire that runs down under the manifolds, then down to the oil switch which grounds it when there is no oil pressure. Just too easy to try it with that off. (only for a minute!), to rule out a problem there. Yea there are smarter ways! On one of my two old CCK's that switch just fell apart inside. I don't know that it ever grounded the wire. Btw, that wire its'self on mine is routed through plenty of places that might ground it. Course I'd be cautious about running it with that off since you might actually have a problem with oil pressure.
 

Power

Registered
If there is any doubt about that wire, or any others. Consider replacing with MTW
(machine tool wire) that is gasoline and oil resistant. Very inexpensive PM.
 

phrankndonna

Registered
I really appreciate all the input and suggestions. I will print all of this out and check it out. I'll also see about the points and condenser - cheap fix if that's the issue. I'll post back with updates. Thanks!
 

bobbyz72

Registered
If it still acts up after the new points and condenser, the next step would be to disconnect the low oil wire and see if it runs correct. If not, then put 12 volt(+) power to the (+) side of the coil, and see if it runs correct, if not, you have a bad coil.
 

lokay5

Registered
Last Subscription Date
01/11/2015
"---Thanks! I'll replace the points. And as for the bad condenser, I remember working on 70's era cars and replacing the points, plugs and condenser, and every now and again getting a bad condenser blah blah blah.......


Well?:shrug:
 

phrankndonna

Registered
Hi again all. Sorry for the delay in responding. I had to go out of town on business. Before we replaced the points, we went through one more time and removed/replaced all connections we could find, and they seemed to take care of the problem. Now we are on to the next issue with the fuel pump.

The fuel pump was bad (the bellows inside was mush), so we are using another off the shelf fuel pump with similar pressure. Although it does seem to work, the hot wire gets VERY hot when connected to the yellow wire that previously connected to the bottom of the old fuel pump. Any ideas of why this would happen?

Again, sorry for the delay in responding.
 

Flintstone

Registered
Resistance in a poor connection can make heat that conducts a wase through the wire. Normally it's pretty clear its the (smoken hot) connection.

Then there is wire sizing. That's what it's all about, sizing a wire large enough to pass the needed current without causing resistance and overheating.
It would seem your pump is drawing more power than the wireing is designed for. Maybe someone here has a better idea for a solution, but one common angle is to use a relay, so the original wireing is only triggering that. Then the heaver gauge you added to and from it handles the current to the pump from, say the Bat. terminal on the solenoid.

(It's the some idea as your starter in your car, those starter cables don't go up to your ign switch!)

You said you changed the points, did you happen to change the condenser as well? Good luck!

Also, just an outside chance, if the replacement pump happens to be 6 Volt, and it's getting 12 that might do that also...
 

phrankndonna

Registered
Hi. First on the points. We actually did not change the points. When we initially weren't getting any spark, we did change the condenser, and that got us to the intermittent spark point. Before changing the points, my dad went through and cleaned up all the connections, and that seemed to clear up the intermittent spark issue.

The pump is definitely for a 12 volts system. And the wire appears to be the same gauge as the yellow wire coming off of the system. I'll double check when I head over there tomorrow. Thanks.
 
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