Gs450l abrupt loss of power?

[Guest]

OK, Im STUMPED!

Got a Voltmeter, left side is about 10.5V, right side, the BEST I could get was 6.3, but mostly it measured mV it was so low. Power is so low it wont even light a test light, left side will easily light one....
But heres whats odd... when pulling the plug and cranking the starter, the plug sparks with no issues.... How could I have less than 1v with the key in the on position at the coil but the plug actually fire when its cranking???

Where do I go from here? Pull and replace all wiring related to the ignition? The only spade connectors I see for the system are the ones at the coil. Anything I can test next?

Ok, either you're measuring in a weird way that's giving those poor results or you have a serious connection issue, which means BassCliff has got the right stuff (as usual )

So, how are you measuring? I need to know exactly where you're putting the positive and negative probes of the multimeter.

If your measuring technique is ok, then it has to be connections and/or grounds.

When I put my harness back on, I gave every single connector a good squirt with contact cleaner and connected and disconnected what it plugged into a few times to give them a good scrape clean. I also visually inspected them to double check everything looked good.

After doing that throughout the entire harness, I still was dropping 1.5 - 2 volts to the coils, so I ended up dismantling and cleaning the ignition switch and the kill switch, and that got rid of the voltage drop so I get 12 volts or more at the coils and have maybe 0.5 volts drop from battery to coils which I'm pretty happy with.

You also need to make sure every harness ground connection is healthy, and preferably move as many grounds as you can to a single ground point that also has a connection directly back to battery negative. This will also help your charging circuit as it needs a good ground to operate effectively.

Welcome to the world of 30 year old Suzuki wiring harness fun

 

[83Rabbit]

Im measuring positive probe to positive coil input terminal and negative probe to negative input terminal with the leads connected to the coil, also tried the same with the leads disconnected measuring the leads themselves.

I see in the diagram that there is one orange and white wire coming from the ignitor and that somewhere it splits to two o/w, one for each coil... Wheres that split?
Whats to clean in the start and kill switch? Those connections are soldered, right?
Thanks for your help again guys.

Odd how this just all of the sudden happened, bike was running well enough for half the trip

 

[Guest]

Im measuring positive probe to positive coil input terminal and negative probe to negative input terminal with the leads connected to the coil, also tried the same with the leads disconnected measuring the leads themselves.

I see in the diagram that there is one orange and white wire coming from the ignitor and that somewhere it splits to two o/w, one for each coil... Wheres that split?
Whats to clean in the start and kill switch? Those connections are soldered, right?
Thanks for your help again guys.

Odd how this just all of the sudden happened, bike was running well enough for half the trip

Ok, when we're talking about measuring voltage at the coils, it's actually from the orange/white to ground somewhere. We want to see what voltage is going to be used to charge the coils up.

Inside the ignition and kill switch there are contacts that meet when rotate it or flip it on/off, and those get covered in crud over time. The contacts in there were quite dirty on mine.

Ignition switch Before:



After:



Kill switch:



I think you'll get the idea...

 

[83Rabbit]

Ah, so positive input on coil, to any ground, coil mount?
Not actually the negative terminal,on the coil itself?
Thanks

 

[Guest]

Yep, that's it, pretty much any bare metal will do, but preferably an actual ground point for the harness or the negative battery terminal.

 

[83Rabbit]

Yep, that's it, pretty much any bare metal will do, but preferably an actual ground point for the harness or the negative battery terminal.

Will do that tonight and take new readings, still odd that one side read so different than the othet.
I did clean up the negative battery lead/ground to the motor last night, that was all rusty, now its shiney

 

[Guest]

Will do that tonight and take new readings, still odd that one side read so different than the othet.
I did clean up the negative battery lead/ground to the motor last night, that was all rusty, now its shiney

Good stuff.

If you want to know the difference it makes, measure properly before and after, you may be surprised at the results, I know I was! Went from something like 10 - 10.5v at the coils to over 12v...

Oh, and if you haven't replaced the glass main fuse in a while, do it anyway as they've been know to measure good but fall apart when being checked... I replaced mine with an inline blade type.

 

[83Rabbit]

Ok, using the new method I got 11.5v for each coil...wth... I guess ill start tearing into the carbs again???

 

[Guest]

11.5 should be workable if not ideal.

Before going back to the carbs, I'd still make sure your sparks are good.

Just eliminate one thing at a time so at the very least you know where the problem isn't...

BassCliff's site has a PDF there on replacing the spark plug caps.

If you don't want to buy new plug caps without knowing if they'll fix the problem or not, you can at least do part of the work by taking the existing ones off, stripping some of the HT lead back, cleaning up the end of the plug cap and putting it back on again.

If one of the plug caps is dodgy, you will probably find it comes off very easily and when you put them back on, you should see a very different resistance figure to what you had in post #15.

 

[83Rabbit]

The caps on there now simply thread into the center of the wire. Ill trim some wire and swap caps, see if that changes any values.
Thanks!

 

[Guest]

The caps on there now simply thread into the center of the wire. Ill trim some wire and swap caps, see if that changes any values.
Thanks!

Yep that's the deal, and good idea to swap.

 

[83Rabbit]

OK what causes the coil to fire? The negative terminal being grounded by the ignitor?

The (-) leads coming into the coil, where do those go?

Reason Im concerned about it still is that the left one is grounded and completes a circuit, the right one does not.... This is with the bike on or off...

Thanks!!!!

 

[Guest]

For a spark to fire, firstly the ignition coil is charged (turned on) by grounding the negative terminal of the primary part of the coil. This is the bit attached to the wiring harness.

Then, when the negative terminal is disconnected from ground (turned off), it discharges via the secondary coil via the HT lead and spark plug, causing a spark.

 

[Guest]

So reading your post again...

Where exactly are you measuring to determine the left coil is grounded?

 

[83Rabbit]

Positive lead to coil to negative lead to coil, measuring between the two the left side reads voltage, meaning the + / - are a complete grounded circuit, the right side reads no voltage when doing + / - coil leads, but when moving the ground test probe to an actual known good ground, a circuit is completed and it reads 11.5 v.

So im questioning why the negative lead/terminal on the left coil is grounded but the right is not...
This is with the key in the on position.

 

[Guest]

Aaaah I think I get you.

If I'm remembering correctly, with the ignition on one coil or the other will be "on" (grounded).

To prove this, rotate the crankshaft 180 degrees and this behaviour should move to the other coil...