[ts_hunter]

( this is an earlier machine with the points ignition)

Checked some things out tonight. Have 12v at + side of coil. Have 12v when cranking at points where wire comes in. Checked resistance of primary and secondary windings on coil, and they are both within spec.

Points are clean and gapped to .016 at the furthest open position. One thing I checked 'just for fun' that seems odd, BOTH spark plug wires failed continuity test with my meter. I double checked with a nail in the garage and the meter beeps when I put the red and black tester on either side. When I tested the spark plug wires, I put one lead on each of the metal ends of the spark plug....no beeps.

What should I check next?

 

[ts_hunter]

OK, I did some more research on the plug wire continuity, sounds like a regular meter won't work on those. Any other good tests to do, or is it time to order parts? I see Onanparts.com has a 'tune up' kit for this B43e that contains, points, condensor, and plugs for $39.

 

[charms]

Tony, you didn't exactly say, but does the 12V on the points wire (negative side of coil) turn off and on as the points open and close?

 

[ts_hunter]

Cliff....I tried to check that, but my meter just shows volts and does not have a light to show voltage on/off. So when I crank I don't really see the on/off happening and it happens so fast the meter can't disply 0 volts and then 12 volts.

 

[wmgeorge]

Tony, did you run some clean paper or card stock through the points? Just wondering as Cliff is weither or not they are passing current? The points are providing a ground for the coil. The plugs fire when the points go open, after being closed.

I suppose you could have two bad plug wires. Yes with the correct meter you can get an ohmmeter reading through those wires. They have resistance wire so it may be up around 5,000 ohms.

But no spark when you have either plug laying on the engine head and cranking?

Darn cold down here in Iowa this morning!!

 

[ts_hunter]

I put some paper through them, and then some sandpaper. Since this thing has been sitting so long (5 years), I think I will just order the points, condenser, and plugs. While I wait for that shipment, I am going to pull the gas tank, check for gunk and make sure the fuel pick up is still intact.

I will report back when I get parts installed.

 

[wmgeorge]

Actually the sandpaper will leave a non-conductive grit behind.

That's why you should follow up with clean business card grade stock.

Not a bad idea to replace it all, hope it makes it run!!

 

[wyogreen]

Tony, you could always turn the engine over by hand to see if the voltage on the negative side of the coil comes and goes. Even when cranking with a digital meter you should see the voltage fluctuate a bit.

Steve

 

[ts_hunter]

Steve,

I did as you suggested and found the following:

Key in RUN position and the points OPEN->
12v at (+) side of coil
12v at (-) side of coil

I thought that was odd, so I disconnected the points wire from the (-) side of coil, and found no volts on the wire coming from the points and still 12v at the (-) side of coil.

Verdict? (my guess is bad coil, but I want various second opinions.)

 

[chuckv]

Tony,

So far we don't have any evidence that either your points or your coil is bad... What is the voltage reading at the negative side of the coil when the points are closed?

The points on your Onan are not a source of voltage but rather a way to ground the negative side of the coil for a portion of the crankshaft rotation. When the points are closed, the negative side of the coil primary should be at about zero volts...this means that the coil has 12 volts across it (+12 volts at the positive terminal and ground at the negative terminal) and current will flow. When the points open then current stops flowing and the magnetic field collapses (and oscillates a bit due to condenser/inductor combination) and a spark is generated by the secondary side of the ignition coil.

Chuck

 

[ts_hunter]

Key in RUN position and the points CLOSED->

12v at (+) side of coil
12v at (-) side of coil

Then with the wire from points disconnected from the (-) side of coil, I have no volts on wire from points and 12v at (-) side of coil.

 

[wmgeorge]

Tony the points provide a ground for the coil.

The (-) or Neg side of the coil should NOT have
+ 12 volt power when the points are CLOSED. When the points are CLOSED the coil is CHARGING.

When the points OPEN (or have poor contact) you will have that +12 volts.

When the points OPEN the high voltage stored in the coil goes to the plugs.

From what you just posted a second ago, that is your problem. The points either have dirt or grease or sandpaper grit or ...... so they are NOT connecting to ground for the coil to CHARGE.

 

[ts_hunter]

Scratch those last 2 entries. I had my black (ground) lead from my tester on the sheet metal around the engine. In another post I saw that I should have it on the negative side of the coil and my red should be on the positive. Doing it that way, I have 0 volts with points open or closed. I do have some voltage (around 9v) coming from the points wire though...battery could be getting a bit weak from the cranking.

With that info, should I go points and condenser, or coil.

 

[wmgeorge]

You had it right the first time. Please clean the points as I suggested, it would take maybe all of two minutes. Make 100% sure the points are closing. Then order your points and condenser If needed.

 

[wmgeorge]

So Tony, is it running yet?

 

[Hammerdown-7]

Hello Tony
The condenser is known to fail on these Onan's. That said, I would suggest replacing the existing condenser with one of David Kirk's Point's saver part's they take the place of the existing condenser and you will have no Other Ignition trouble's ever again. I hope this help's, Kurt



http://www.kirkengines.com/index.php#PositiveGroundPointSaver

 

[knottyrope]

points will have a light blue spark when condenser is working right barely visible in sunlight

bright orange spark means condenser is bad

 

[wmgeorge]

Knotty that's a good tip. The condenser can either be shorted to ground which an ohmmeter can pick up or open which would cause the points to arc like you said.

 

[ts_hunter]

I have points, condenser, and plugs on order from OnanParts.com. They are on 'vacation' right now and will start shipping again on 1/5. In the mean time I flushed the gas tank, put a new fuel pickup line inside the tank and installed a new battery. I will update again when I get the parts and install them.

 

[ts_hunter]

IT'S ALIVE!!!

I got the points, condenser, and plugs about a week ago and it is a hot, balmy day here in MN (33 degrees), so I put the points in, just the points. Poured a little gas down the carb and she came to life. It runs OK a low speed, but at higher rpms it likes to surge, which I knew from the previous owner. I did take a look at the low idle jet a week or so ago and all the passages were open. I think I will do some more cleaning in there and if that doesn't do it I will look at the intake manifold. I will put the condenser and plugs in also, but just wanted to do one at a time for diagnosis purposes.

I have seen posts about running an unlit torch near the manifold to see if that stops the surging. How does that work? Does the suction from the leaking manifold pull in the propane and then burn it in the engine, therefor stopping the sucking of air?

BTW, thanks for all the ideas and help on this guys.