Pre-MCI Spark Issues

[GreaseMunkey]

Well guys, I’ve hit that point in my project…

I’m returning a pre-MCI cart and it ran fine until I got it shined up and got the brakes working. I took the control panel off to clean up the wiring and remove the reverse buzzer that was partially bypassed and didn’t work. Now for some reason it won’t fire and my head has been spinning for 2 weeks now. I’ve googled and scoured the forum for possible solutions and still can’t definitively figure out where my problem lies. It’s killing me that such a simple electrical system has me this stumped, I’m a controls engineer by trade and work on WAY more complex systems with nowhere near this much trouble.. When I first try to crank the engine I get one spark and that’s all, nothing if I keep turning it over.

Here is what I’ve checked so far.

Grounds, grounds, grounds… (all of them MULTIPLE times)
Pulser - 20-23 ohms
Pulser signal - 0.23-.31 VAC while cranking
Coil - 3.6 ohms (primary); 16.4k ohms (secondary at plug wires)
Coil signal - 11-13v on “+” and identical on “-“ while cranking
Ignitor - nothing shorted to ground[/INDENT]
The two potential issues that I have stuck in my head are:

1.) If I put a test light across the primary coils it lights and stays lit, it’s not pulsing. It’s mimicking the single spark that I’m getting.

2.) The power wire going to the starter has continuity back to ground. (I couldn’t find anyone on here, google, or YouTube checking continuity with A2 and F1 jumpered together. I took the jumper off and A2 is the post that has continuity to ground (A1) and best I can tell it’s supposed to have continuity to A1.


It kills me that I had NO electrical issues until I tried to make it pretty. It didn’t have a good ground the the frame when it was running, during said wiring beautification I sanded the back of the plate to give a good frame ground.

Any help is greatly appreciated, I will torch this B before I unload the high dollar parts cannon at it!

[Cartmaster]

looking at the tests you have performed, My conclusion is that the igniter has failed. As long as you have continuity in the wiring between the pulser, coil and igniter, you have AC reaching the igniter from the pulser, the coil has a positive supply and igniter has a positive supply and ground, then the ground to the coil is not being switched by the igniter. Simples!!!!! If you are seeing positive on both sides of the coil primary, the coil is good, so it has to be missing the ground signal.

A single spark is a classic symptom of a failed igniter. The only other thing to possibly check is that the igniter is seeing above 9 volts when cranking or it will not operate. If the volts are low, it may be worth checking the ignition switch and the pedal switch for a high resistance.

Make sure all your connections along the way in the Ignition circuit are passing current before completely dismissing the igniter.

The OEM igniters are obsolete and the cheap clone ones on Amazon and ebay are pretty hit and miss. Many people have had good results with the Red Hawk brand.

Hope this helps.

[GreaseMunkey]

That definitely helps! I was hoping it wasn’t going to be the ignitor after seeing the everyone agreed that the replacements are 4:1 trash, but I was kind of leaning to the direction that it was my issue.. Especially when I could unplug the pulser and get the same single spark condition.

Have you seen where people had better luck buying used ignitors from a cart graveyard vs buying new likely DOA ones? I’ve got a guy in town that I’ve bought several parts for this build from that has a pretty vast selection of project carts that I could potentially land a used one off of.

[Cartmaster]

That would be your best bet, grab a few used ones and try them LOL.

[GreaseMunkey]

I’ll go grab them tomorrow and update accordingly.. I’m gonna be sidelined within the next couple of weeks with my attempt in trying to help populate the world, so I’ve gotta get it to it quickly.. The wife isn’t going to take too kindly to me in the garage at 2am with a newborn in the house! Haha

[Cartmaster]

Best place to be with a new born.

Keep us posted. There are a few of us trying to work out a suitable alternative ignition module to keep these things alive for a bit longer.

[CP241]

Originally Posted by Cartmaster

Best place to be with a new born.

Keep us posted. There are a few of us trying to work out a suitable alternative ignition module to keep these things alive for a bit longer.

And I would know



It’s hard to test the ignition switch and pedal switch without loading the circuit. It’s easier to just bypass them… just use a jumper between the 2 wires and bypass it completely. If it fires and runs you know it was bad.

The pedal switch in particular is known to cause this exact same issue with one single spark. But it’s basically the exact same circuit as the key switch so if you messed with the wiring back there cleaning up some other monkey’s “work”
Then there may be a bad connection or something along the lines back there as well causing the issue so it’s worth bypassing the key switch also just to test.

And if the monkey had wired other things into the circuit make sure there’s nothing else that may be robbing the available voltage as well.

[Cartmaster]

To be honest I just jump the solenoid activation coil directly from the battery and see if it fires up LOL. This overrides everything and if it fires up you then need to do what CP said and bridge each part of the circuit separately to find the offending item.

Also as CP said, messing with the reverse buzzer switch can affect the connections there too as power goes to the reverse switch from the solenoid on a fused wire, piggy backs off there down to the pedal switch, then comes back and is connected to a green wire that goes to the ignition switch and from there to the solenoid on a blue wire. Maybe you have just created a bad connection there?

So the circuit flows as follows. power from solenoid via a fuse feeds the reverse switch and the pedal switch, when the pedal switch is activated it sends power to the ignition switch which then powers the solenoid coil. It seems backward, but that is how it works LOL.

Knowing this, you can easily identify which wires go to and from the pedal switch and bridge them right by the reverse switch These wires will be in a gray sheath

More often than not, this problem is caused by the pedal switch as it can get water in the box when washing the cart and ruin the microswitch.

If I can find it I have seen a video that see's a very similar scenario only on an MCI with a very weak spark, but it is exactly the same circuit as the Pre mci, just a slightly different pulser, coil and igniter.

EDIT.

Found it. When i first saw this video, as soon as he said it went through water and cranks as soon as you turn on the ignition but weak spark, I knew it had to be the pedal switch causing all the problems. It may not be relevant to your situation but worth checking out. You say you have power at the coil and no signal on the ground, so I still think your issue is likely to be the igniter. A simple test for the coil side of things is to remove the signal wire from the coil and flash that terminal to ground to see if you get a good spark.

https://www.youtube.com/watch?v=4toysMe0G8E

[GreaseMunkey]

I should have specified in the original post, I bypassed all of the controls and went straight from the fused wire off of the hot side of the solenoid to the coil on the solenoid.

Also, I’ve tested the the 12v from the battery to the coil, and also tried going straight to the battery with that wire. The “-“ side of the coil with the wire from the is showing 12v constant just like the hot side of the coil. However if I take the wire off of the “-“ (white wire from the of ignitor) off of the coil I don’t have anything on it.

When I saw that I was getting 12v on the white “-“ wire on the coil, I was only getting it when the wire was plugged in partially. If I take the white wire off of the coil it’s showing nothing, 0v to battery hot and ground.

Could the 12v be leaking through the coil from the “+” side of the coil?

When I have everything connected correctly and hook a light to ground and probe the “+” or “-“ side coil, I get a solid light no pulsing at all. Is the “-“ side supposed to be pulsing a ground signal from the ignitor?

[CP241]

Yes, the (-) side of the coil should rest at 12v and the ignitor will pulse ground to activate the solenoid and fire the plugs.

Red wire should always be 12v