Tracing electrical problem

[thefoolofemmaus]

Hey Crew,

I am trying to diagnose a no spark issue. The voltage at the battery reads 12.6. At the hot side of the starter solenoid it reads 12.6. Once the solenoid is closed, the voltage drops to 9.4. Is this expected, and if not what are possible causes? My google fu has turned up nothing.

Edit: Wanted to say the voltage drop occurs even when I bypass the solenoid, connecting the two wires together directly.

 

[fastbysuzuki]

Do the quick test and post the results https://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST/page9

it would help if you say what bike you have the problem with it's a good idea to put the model and year in your signature so everyone knows what bike and it saves you typing it in every post.

 

[LAB3]

My first best guess is a weak battery, how old is the one you have?

 

[Redman]

. . . ... . . . . . . . . . . . . . . . . . . . . . ..... ... ... Once the solenoid is closed, the voltage drops to 9.4. ........

12.6 is a well charged battery.

But voltage dropping that far is probably a weak-marginal battery.
How old is it? Has it sat uncharged for a long time?

Is a chance could be problem in the starter motor.
Did it turn the engine okay?

I suspect the battery mostly.

 

[Steve]

Replace the battery, try it again.

If you want to prove it's the battery before you spend the money, connect your car to your bike with jumper cables, but be SURE the car is NOT RUNNING. You are not trying to "jump start" the bike (which does not require the engine running, either), you are only substituting a known-good battery.

Feel free to monitor the car's battery while you try to start the bike, but you probably won't see much of a voltage drop, if any.

.

 

[thefoolofemmaus]

Not sure how old the battery is, the PO put it in. It currently does not have a full charge, I've been jumping it off the car.

 

[thefoolofemmaus]

The battery was older, but this was done while jumping the bike from my car. The starter turns the engine.

 

[LAB3]

Damn, that's one heck of a lot of drain! It would make sense that the wiring harness would start on fire if the fuses where somehow bypassed trying to handle that kind of draw. It would probably make more sense that the main positive lead to the starter is grounding but chances are you'd hear it crackling. I'm gonna say the starter itself is shorting internally or has a huge issue making good contact somewhere inside. Give that positive cable a good looking over then consider pulling apart the starter, rebuild kits are relatively inexpensive or if you can get things cleaned up a set of new brushes certainly isn't too much money being wasted.