2002 Robin 350 voltage/spark issue

[Walkbyfiath33]

Ok so I have owned and worked on small engines a good bit but recently got my first golf cart. I have been attempting to get spark on my ezgo for the last three days and have recently come to a point where I believe I need some assistance or recommendations. So far I have successfully got all the wiring setup as the diagram suggest and cleaned up a lot of the contacts and even replaced some bad wires. Continuity from the positive to the coil is great but what I have come to find is there is something causing the voltage to drop as it makes it's way through all the wire.

Basically the + battery wire goes to the always hot terminal at the starter solenoid and its 12v when running. But the further I get down the circuit it drops about .2v per every 3 feet (when running) of wire all the way up until it hits the smaller hot terminal of the starter solenoid. By time it gets to this point it has gone from 12v down to roughly 10.2-10.5v. And so of coarse it only sends that 10.2v. to the coil.

I had my good friend who works on small engines for a living (outboard engines) and even he was kind of confused by the setup and wasn't sure what was happening after messing with it for a couple hours. We did jump the + battery terminal to the hot small terminal on the starter solenoid and saw a spark only at the initial turning of the engine and when the key was let off. So even with 12v at the coil something is off.

If anyone has any recommendations as to what the next steps I should take in diagnosing the problem that would be great. Here's what we already tested.

The coil - continuity is solid from positive to negative tabs and from coil plug to coil plug (within range)

Tested the pulsar coil and it's functioning properly (he had some fancy tool from work that measured it when running)

And so by my understanding if the pulsar is sending correctly than the igniter must be working right.

Continuity from the + big terminal of the starter solenoid all the way to through the circuit to the smaller hot terminal on the starter solenoid is solid. And then we did all new wires and connections to the coil and pulsar coil. So there isn't any corroded wires/loose connections in the circuit up to those parts in the ignition process.

My best guess is something is pulling current away from the loop causing resistance but I thought maybe if I explained it somebody would have a better idea as to what's going on. Sorry for the long explanation. Just wanted to rule out as many things as possible ahead of time.

Thanks for reading this. Any help is appreciated! Thanks

[Cartmaster]

You have not mentioned the ground side of all this. That would be the first place I would go to check for any high resistance. Clean all ground connections thoroughly and test for resistance when re assembling. The most common place this shows up is in the plate that the battery ground cable goes to due to corrosion over the years. These things are assembled as painted parts and are relying purely on the bolts to supply a ground connection. You have wired power directly to the energizing side of the solenoid, so ruled out the ignition switch and pedal switch part of the circuit which is a good start as these often allow crank but no spark due to voltage drop. keep at it you will find the problem eventually.

If you confirm good grounds, it may be worth checking for voltage drop directly at the solenoid. Burnt contacts here will show a drop in voltage along the circuit. The more load it sees, the more voltage drop ( Resistance ) will be seen.

If nothing else works i would then suspect the igniter as being faulty. If this cart has the pre MCI engine, good luck in finding an OEM igniter LOL. Used working ones are the only real option these days. Dont even consider a clone from ebay or Amazon. They rarely work right out of the box. Same with coils and pulsars. These parts can be picked up used from people who have done Big block or bike engine conversions etc.

Originally Posted by Walkbyfiath33

And so by my understanding if the pulsar is sending correctly than the igniter must be working right.

Not true as far as i am concerned. It is the Pulsar that tells the igniter what to do!

[Walkbyfiath33]

I appreciate the input. After running continuity on all my grounds. I found a lot of resistance from the hot small terminal of the starter solenoid to the grounded small terminal of the starter solenoid. But great continuity from the ground small terminal to the ground of the battery. Is it safe to assume that the starter solenoid is not functioning correctly?

[Cartmaster]

It is never safe to assume anything yet lol, it may be that you are reading the activation coil and not undue resistance. I am trying to picture the circuit in my head now. I think the +ve supply for the ignition circuit comes from the cold side large terminal of the solenoid, via a 7 -10 amp fuse. If so you might see a poor connection around there. It is known that the fuse or holder can be a point of contention with high resistance. Might be worth checking out. We have already eliminated the ign and pedal switches by hot wiring the solenoid, but you say you are losing volts on the ignition supply. If you have a resistive fuse/holder, spade connection etc, when the solenoid activates, it draws high current for the starter. This will pull down any voltage at a high resistance point. The clue here is a single spark when pushing the pedal. It is not conclusive as other scenario's can cause a single spark too. One being a bad igniter, another is a high resistance pedal switch, or just a bad connection in the solenoid activation circuit. We just need to methodically rule these things out. Remember, hot wiring the solenoid +ve, does not hot wire the ignition circuit.

[Cartmaster]

Also, remember I am uk based so timing for my replies may not be quick lol

[Walkbyfiath33]

I have been using this diagram for the wiring to check everything. ( See attached) Also the ignition circuit where the black wire with the 7amp fuse is starts on the always hot terminal of my golf cart.

[Cartmaster]

Oops, I should have known that. The fuse covers solenoid activation not ign circuit. I think we are left with just a bad connection around the solenoid and Igniter/coil or it is simply a bad igniter or coil. I am not sure if you can flash these coils to ground to test for spark or not. But if you look in the tech section for ezgo you should find the test procedure for ohm testing of the coil windings. I cannot remember right now what the impence tolerences are, but another member may be here soon with that info. There is no known way to test the igniter except install it in a working cart to try it or borrow a known working igniter to try on your cart.

Just so you know, I am out and not able to access my files.

[Walkbyfiath33]

Ok so the resistance I was seeing from the smaller positive terminal of the starter solenoid to the ground was just the 2.8 ohms that the coil itself is supposed to take. So that makes sense.

[trig123]

You don't have your battery in backward do you ? very easy to do as both cables are black.
If someone does put a battery in backward they will spark one time when you let off gas pedal.
As far as the volt drop of 10.5. I have three of these carts and that's all I get when checking with meter at small terminal of solenoid when spinning over and they all fire and run great.
What brand ignitor do you have ? . If its OEM you will see markings on it. If its the cheap china one nothing will be written on it.

[Walkbyfiath33]

Oh well that would change everything. If I'm getting sufficient power at the coil then I should be looking elsewhere. Interestingly after cleaning up my grounds best I could I get spark only at the start and end of cranking with the pedal. Which as you stated is a common battery backwards problem. But looking at the diagram I am positive I have the correct hookups though