Only getting one spark from plug...why?

[User]

I have just gotten my scoot to a point where I can observe the behavior of the starting and ignition systems. After installing the wire harness, and all of the needed electrical parts, I pressed play. I get nothing from the plugs until I let off of the starter button.

I have 12v at the coils (thanks to the coil relay mod.)
RR is new.
Plugs are new.
Battery is new.
still have a few checks to make and tests. (I still need to test the Ohms of the coils, and signal generator.)

Just thought I would try and save myself the troubleshooting trouble and ask here in the wealth of GS knowledge. I tried to search, but haven't found any good returns for a search on the subject.

Thanks in advance for your help and advice.

Regards,

User

[tom203]

I have just gotten my scoot to a point where I can observe the behavior of the starting and ignition systems. After installing the wire harness, and all of the needed electrical parts, I pressed play. I get nothing from the plugs until I let off of the starter button.

I have 12v at the coils (thanks to the coil relay mod.)
RR is new.
Plugs are new.
Battery is new.
still have a few checks to make and tests. (I still need to test the Ohms of the coils, and signal generator.)

Just thought I would try and save myself the troubleshooting trouble and ask here in the wealth of GS knowledge. I tried to search, but haven't found any good returns for a search on the subject.

Thanks in advance for your help and advice.

Regards,

User

I take it this is the 85 gs550 ? put it in your signature, so more folks will be teased into response.
Yeah, you do have a few more checks, cuz it's not right. When you say it has spark when you let off starter button, do you mean spark plugs seem to fire or that you have 12 volts at coils? Starter button and kill switch share same positive feed- if one was grounding out somewhere, it should trip fuse.

[Redman]

...
...
.... I get nothing from the plugs until I let off of the starter button.

I have 12v at the coils (thanks to the coil relay mod.)
...
...

I would say that battery is low.
And then voltage is drawn lots lower when the starter motor is drawing power also, and voltage is so low that ignition doesnt work. WHen you let off the starter button then the voltage comes back and ignition can make a spark or two while engine is still spinning.

But you say is a new battery.

Hum, did battery get a good charging?

.

[User]

Yeah, I was talking about the 550es. Didn't realize that I hadn't put that in the thread. I will try to update the signature soon. Thanks for the advice.

I didn't have a chance to do any more testing this evening, perhaps tomorrow I will have some time to tinker.

As far as I can tell the battery took a good charge. I followed the charging directions that came in the package. However, it was a cheapo battery so I don't doubt my luck of getting a lemon for trying to save a few dollars before I got too involved in this scoot.

When I hit the starter button I don't get any spark while the starter is cranking the engine. As soon as I let off the button, I get one big bright blue spark. Nothing else, no matter what. Same result every time the button is pressed.

I will post more when I get a chance to play with the multimeter some more. Just curious if the mentioned conditions would trigger someone's brain to point me in a certain direction. Or if anyone has seen something similar before...

Thanks for the replies.

Regards,

User.

[User]

Tested the signal generator and the coils this evening with the multimeter. Both passed spec as per manual. Although, I decided to check the igniter box against the specs in the manual and I am getting some funky readings that don't make any sense at all. I am leading towards a screwed up igniter box. So I will continue my search for one, and see if that fixes my troubles. Anyone had an igniter give them this trouble? I have read that they either work, or they don't. This would seem to break that theory, but I'm no expert.

I have read that there have been attempts to repair an igniter, but I doubt my ability. Although I can access the interior of the box very easily. I don't smell anything burnt, or see anything damaged. The exterior of the box is aged and rusted, but I wouldn't think that would have a bearing on it's function. Perhaps my project is on hold until I can find a replacement.

Any suggestions for repair or replacement would be greatly appreciated.

[81gs1100]

So do you have 12VDC at the coils while cranking the motor over?

[User]

So do you have 12VDC at the coils while cranking the motor over?

Didn't think to check it while I was cranking the engine. That's a negative. I just went to the garage and checked the voltage while cranking and it instantly drops to 9.25V when I hit the starter button.

Bad battery?

[SqDancerLynn1]

Check the voltage at the battery when cranking, if it drops to 9 volts the battery is probably bad and you need to have it checked

[81gs1100]

Also, make sure you have a good ground for your batt. I have seen, ok i admit after putting an engine back in I may have not secured the ground and the bike would turn over but not start. it turned over sorta weak. the other grounds were to the batt, but not enough to get a good circut to pull the amps and voltage needed.

[User]

Also, make sure you have a good ground for your batt. I have seen, ok i admit after putting an engine back in I may have not secured the ground and the bike would turn over but not start. it turned over sorta weak. the other grounds were to the batt, but not enough to get a good circut to pull the amps and voltage needed.

I have very recently cleaned and sorted all of the grounds, and connections in the harness. That was one of my first priorities after reading some of the troubles that these bikes have with electronics. So the ground is good and clean/strong.

Is there any other way to test my battery? A secondary test to prove it is bad? I already tested while cranking, and I only get 9.25V at the coils when turning the starter.

Regards,

User

[tom203]

I have very recently cleaned and sorted all of the grounds, and connections in the harness. That was one of my first priorities after reading some of the troubles that these bikes have with electronics. So the ground is good and clean/strong.

Is there any other way to test my battery? A secondary test to prove it is bad? I already tested while cranking, and I only get 9.25V at the coils when turning the starter.

Regards,

User

If you're only getting 9.25 volts at coils during cranking, the same is at the ignitor which might be too low. On mine during cranking, I get 10.5 volts to coils and that's probably marginal. Either your battery is weak , connections poor or starter is drawing too much.Can you jump it with a NON- running vehicle and see if that helps?

[User]

If you're only getting 9.25 volts at coils during cranking, the same is at the ignitor which might be too low. On mine during cranking, I get 10.5 volts to coils and that's probably marginal. Either your battery is weak , connections poor or starter is drawing too much.Can you jump it with a NON- running vehicle and see if that helps?

I will try this when I get home this evening if I have the time. How would you know if your starter was drawing too much? I would think that was a set value needed to operate the starter.

[tom203]

I will try this when I get home this evening if I have the time. How would you know if your starter was drawing too much? I would think that was a set value needed to operate the starter.

Not easy to tell ( without a big ammeter); basically the starter has to get up to speed quickly or it will draw excessive current, thereby dropping the battery voltage. If you feel your connections are all good, I'd suspect the battery before the starter. My starter is original at 38k.

[User]

Connected a pair of cables from the truck battery to the bike, and tested the voltage again at the coil and it still dropped, but not as much as before. It went to 10.5V at the coils, but still only got a spark when I let off the starter button. I am starting to think that the battery isn't the issue. I can only think that it is the igniter box due to the results of the test being oddly unlike the listed ohm values in the repair manual.

I have the igniter box apart right now going over all of the solder joints and looking for possible failures.

Any other ideas? I have been looking for an igniter box, but having minimal luck.

Thanks in advance,...again.

-User

[tom203]

This business of only getting a spark when you let off starter button makes me think of a wiring problem. The ignitor works by turning on/ off negative side of coils; but if the negative side of coils was always grounded ( bad ignitor or wiring grounded out between ignitor and coils), you get a spark only when you cut off the positive feed to the coils.
Try Mr. Matchless' signal generator test- with ignition on, wave a small screwdriver tip in front of signal coil for #1 and #4 plug, those plugs should fire. Repeat for signal coil for #2 and #3.