No Fire To Spark Plug 149 Cub Cadet

[twoton]

Hmmm,... So I guess Bob's out at the moment. This "test" got me thinkin about this old post about putting the ignition on a separate switch (just for discussion purposes and all, no beatin each other over the head);

http://www.onlycubcadets.net/forum/s...=33676&page=18

[twoton]

And I don't mean to take Don's recommendation out of context as I know he was talkin bout pullin tractors...

[twoton]

But, if Bob did everything that Roland suggested:

Originally Posted by R Bedell

......

(A) Download the Wiring Diagram found in the Technical Library section, located on page 5.

(B) Wire the tractor per the Diagram.

(C) Ensure that the Battery is good and properly charged.

(D) Use only the correct Cub Cadet Parts.

If you simply follow through with the above, then your tractor should start & run.

The ACR thing will have to be addressed.

But, chose not to fix the ACR, at least not now.. that's kinda the shittuation he has, excessive compression making it hard for the starter to both spin over the motor and fire the ignition at the same time?

[twoton]

As I’m thinking bout this test and the “You gotta disconnect stuff” , “NO! You don’t gotta disconnect stuff” discussion, it makes me wonder about the proper operation of the condenser as part of the ignition system. I got this book some years ago;

https://www.amazon.com/dp/B002I8H4WE...V170RD6O&psc=0

it has some interesting information in it and with regards to function of the points and condenser;

from page 131… in the split second that the gap resistance starts to create a voltage drop in the battery current, the potential (voltage) stored in the condenser will be greater than the battery voltage across the contacts. This being the case, the condenser instantly begins discharging back through the circuit, in opposition to the battery current. Thus, it effectually heads off and instantly stops the battery current, so that the contacts make a clean break, without any arcing of current across them…..(and on and on blah blah blah).….. we say that the condenser discharge constitutes an oscillatory current of rapidly diminishing value”

So,.. without typing out the entire half page of info about this all (my arm is still really hurting) I would think that if one was to engage in this “test” the second battery source and the function of the points/condenser should be isolated from the starter circuit? Yes? No? I thought that it was a bad idea to provide a secondary ground path...

Sorry, just trying to figure this out…

[twoton]

Sounds like Bob should get a higher rated battery, put his ignition on a toggle switch and once he gets it crankin, flick the switch! Or maybe fix the ACR...

[Gompers]

Originally Posted by twoton

As I’m thinking bout this test and the “You gotta disconnect stuff” , “NO! You don’t gotta disconnect stuff” discussion, it makes me wonder about the proper operation of the condenser as part of the ignition system. I got this book some years ago;

https://www.amazon.com/dp/B002I8H4WE...V170RD6O&psc=0

it has some interesting information in it and with regards to function of the points and condenser;

from page 131… in the split second that the gap resistance starts to create a voltage drop in the battery current, the potential (voltage) stored in the condenser will be greater than the battery voltage across the contacts. This being the case, the condenser instantly begins discharging back through the circuit, in opposition to the battery current. Thus, it effectually heads off and instantly stops the battery current, so that the contacts make a clean break, without any arcing of current across them…..(and on and on blah blah blah).….. we say that the condenser discharge constitutes an oscillatory current of rapidly diminishing value”

So,.. without typing out the entire half page of info about this all (my arm is still really hurting) I would think that if one was to engage in this “test” the second battery source and the function of the points/condenser should be isolated from the starter circuit?

Sorry, just trying to figure this out…

That explanation of a condenser’s function is a little simplified and, from my understanding, wrong. Capacitors (condenser in this case) resist changes in voltage, while inductors (the coil) resist changes in current. Putting the two together creates a simple oscillator.

When the camshaft pushes the points open, it breaks the circuit that is completed through the primary windings in the coil. The magnetic field that is created in the core of the coil by the current flowing through the primary windings (when the points are closed) begins to collapse and this collapse induces a very large voltage into the secondary coil windings, which flows from the secondary coil windings through the spark plug electrode and jumps the gap from the electrode to the ground creating the spark. As it collapses, it also induces a relatively large voltage in the primary winding that might jump the gap in the points.

The point of the condenser isn’t necessarily to provide voltage to fire the spark plug, but it’s to stop the current flowing through the primary winding from the collapsing magnetic field from reaching the points and jumping the gap. It’s sort of like an electrical “bumper”. The condenser charges to absorb the current spike from the collapsing magnetic field and then discharges after the current stops flowing partially rebuilding the field in the coil, which then collapses again, but less this time, charging the condenser, which discharges, but less. It’s a simple oscillating circuit that “rings” when you open the points. All this happens while the points are open.

When the points close again, it completes the circuit and the magnetic field rebuilds in the coil starting the whole process over again.

In short, the engine would run fine for a while without a condenser, but the points would be sparking every time the points opened and it would shorten the life of them significantly.

[twoton]

Thanks for the input there Gompers. I did simplify the explanation by deleting a whole bunch of stuff in the …..(and on and on blah blah blah).….. area. What really amazes me is how the condenser actually reverses the flow of current back through the primary coil, through the battery and the ground, and into the opposite side of the condenser. Recharged by it's own discharge. And how quickly this all happens, over and over again! That's why it seems that isolating the ignition circuit from the starting circuit during this "test" would make a lot of sense. To me anyway.

[J-Mech]

Well.... no, it wouldn't run fine. I guess you've not ever had an engine with a failed or not grounded condenser. They will backfire, buck and just all out run like crap.

But to answer twotons question (? I'm not sure there was a definitive question) no, the condenser does not need to be isolated from the cranking battery, or the cranking battery disconnected from the ignition system. It (the condenser) will do it's job when attached to the coil/points no matter what.

The cranking battery doesn't need enough "help" to spin the starter so a secondary source isn't going to backfeed. How about this.... you could just attach another battery to the tractor battery via jumper cables, and it will do the same thing as just powering the ignition separately. *IF* the issue is lack of voltage for the ignition, it will function fine.

*More shortly*

[twoton]

Originally Posted by twoton

....get a higher rated battery...

Originally Posted by J-Mech

.... you could just attach another battery to the tractor battery via jumper cables...

Cause ultimately, what Bob is trying to do is get some extra amps into the system.

.......

[J-Mech]

Maybe this will help:

Electrical systems/ electricity function exactly the same as a hydraulic (meaning fluid) circuit.
So, picture the battery as a water tower, or a pump (depending on which idea works better for you). All the wires are water lines. Some bigger, some smaller. Now the wire (pipe) coming out of the battery is a certain size, and therefore can only let so much "water" out of it. When you engage the starter, that main line is opened up all the way directly to the starter. ALL the power the battery can provide via the cable (water line) starts flowing to the starter (according to load). When that big valve opens, if the load is great enough it may pull all that fluid down that open line as it is the path of least resistance. SO, the "water" in the remaining lines also drains (loss of pressure or voltage) to help supply the need at the starter. Adding another "water tower" to the battery or simply powering up the coil alone, will replace the loss of "water" needed at the coil.

Now the main system, even if it needs more pressure, will not be able to draw enough through the little wire (attached to the coil via a second battery) to help the starter because it's just too small. Is it possible to overload that circuit.... in theory, yes. But only if the cranking battery is dead, or not present. Even then, it is more likely that because the starters demand is so great, it would be like hooking a garden hose to a fire hose and trying to use it. The starter would just groan, or the solenoid click from lack of "flow". Now, if you continued to hold the starter engaged with only the small wires attached and back feeding from another battery, yeah.... they would likely start to get hot. But it's not going to be immediate. It's not a dead short, it's just an overload on not a big enough line. Big difference. Takes time to heat up from overload. Dead short is like a light bulb. INSTANT and maximum draw that gets hot NOW. Example: Failed v-regs on the old S/G systems will occasionally fail and once the starter is engaged, short to the armature and when you let off the key, the starter will continue to crank. Doesn't crank fast..... but still cranks. When I've had it fail, I was able to get a wrench and disconnect the battery before wires burned up. They got pretty warm, but didn't burn up. Simple repair of the v-reg or replacement and all was good.

Lets go back a bit:
On the older starting systems, there was a terminal on the starter solenoid marked with an "I". This was to be used for the ignition system. Just as I explained above, the older batteries were small, and the ignition system would lack adequate power to supply voltage to the ignition during cranking. All the electricity was "flowing" (like water) to the starter. The solution: Add a terminal at the solenoid where all the power was going, and run it directly (second wire) to the ignition coil. Since the power was flowing to the starter, they simply tapped into that source and fed the ignition. As a note, even if this tractor has an "I" terminal on the ignition, tapping it wouldn't help, as the simple truth is the sytem is so small, and the fact that the solenoid is so far away from the starter, it wouldn't make a difference. On the system I am describing, the solenoid was mounted to the starter, and coil generally not far away.

Does any of that make sense or help?