Weak battery? No spark?
 

I've charged the battery up and it turns the engine over fine, but I get no spark or volts on the negative post on the coil. Could this be caused by a weak battery on this 128?

Ive replaced the V/R, coil, condenser, solenoid, new wire harness.

It had spark last week but the coil was going bad so I replaced it now no spark.

The battery is 3 years old

Do you have power on the + side of coil with the key turned on?

Can you see spark at the points?

A low voltage battery can cause a no or weak spark. BTDT.

Click on this link and with a DVM or VOM, you can trace the issue down....... Diagram

I am no expert but could there be a problem with your ignition switch? That is about the only thing you did not replace.

Great point Paul. Kinda what I was thinking. Looks like the points weren't replaced yet either. Maybe a quick clean with some emery cloth would help.

I have a new set of points laying around, ill replace them today.

Ignition switch was replaced with one off of another cub but its still could be bad.

12v power is going to the positive post on the coil.

IF you have 12VDC on the ( + ) and ( - ) side of the Ignition Coil and still have no spark, I would look at the Spark Plug Wire and/or the Spark Plug itself. This is assuming the Ignition Coil is working correctly.

I dont have 12v at the negative post when I crank the engine, only the positive.

Take the neg wire off the coil and see if you have 12V.@ the coil with key on and/or cranking,
if so, then the problem is in the points/condenser or shorted wire to them.

Here is a quick test you can perform. Take everything off the negative Ign Coil Term. Install a jumper wire on that terminal. Turn on the Ignition Switch. With the opposite end of the wire, touch the motor block (ground) momentarily, if all is well, you should see a small spark at the end of the wire and spark at the Spark Plug.

http://i176.photobucket.com/albums/w...COILTEST-A.jpg

OR.....

Take everything off the negative Ign Coil Term. Turn on the Ignition Switch. Take the black or negative meter lead and attach to motor ground. With the Red meter lead, if all is well, you should have 12V at both the positive and negative terminals of the Ignition Coil.

http://i176.photobucket.com/albums/w...COILTEST-B.jpg

ok, thanks ill try those tests and report back

You sure you got the coil back in right? I'd check the simple things first.

Are the points opening and closing? I'd change pr adjust as few additional things as possible before checking all the basics.

How did you determine the coil was "going bad" ... spark beginning to fail?

John

I heard that if the coil got really hot when it was running that it was going bad, And it was getting pretty hot.

Now wait a minute...........there was NOTHING said in the original post about the Ignition Coil being "hot". Are you saying now.......that the coil has been running hot....???:bigeyes:

Sound advice here and good illustrations cub 128. Really worth the investment to buy a DVOM no matter what kind you get. These checks will let the meter show you what's wrong rather than "swaptronics". I'm sure there are primary and secondary resistance readings that you can take on the coil as well to see if it is bad but again a meter is a valuable tool that saves a lot of time in troubleshooting. I have a Simpson analog and Fluke 87 that I use every day to work on electric lift trucks and its well worth the time and effort to learn how to use one for whatever electrical system you're wanting to diagnose. Just my .02.

Yeah the coils been running hot, but I got it going today. It was the points. I mowed for a couple hours and all was well except I think the engine is running hot because the carb bowl was at 157* F I don't know if that's normal or not.

Ive got all the tools that I would ever need to do anything on these just not familiar with them or battery powered ignition coils.