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Discussion Starter #1
First off hello and thanks for having me. I had to venture out to different forums because the ones I was in didn't really have any active members who were able to help or even respond. Now before anyone starts throwing stones at me please forgive me I drive....eh... I drive...uh I mean I drive a scooter........ sorry but I do for now :(

I know it's not the same as a rocket but a lot of the parts are very similar from motorcycles to scooters such as the Yamaha Lean angle sensor. I believe Yamaha motorcycles carry the same one as Zuma 125 scooters. I have checked everything in the ignition circuit diagram, replaced stator and ignition. Tested the kickstand sensor, engine stop switch, main switch and main fuse. I have verified everything checks out I even have ground to chassis so I am down to 3 suspects. 1.)ECU 2.) Lean Angle Switch 3.) Some type of short in the wiring. 4.) Just thinking about it maybe I have a voltage drop issue.

I am not the type to quit but man this scooter has been kicking my ass.

I checked my lean angle sensor for voltage and at level it is around 4 volts and 45 degrees or more it reads at .8volts. The service manual says anything less than 45 degrees should read .4Volts and greater 1.4volts but the sensor is clearly adjusting voltage as its rotated and I don't have much confidence in the numbers I always see different specs other than what the service manual calls for and the part still works. If anyone can share any insight I would appreciate it I am pretty desperate at this point thanks.
 

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I have never heard of a lean angle sensor...and wouldnt think it would lower the volatge as the lean angle increased...very dangerous since the last thing you want is the motor quiting while you are leaning over,presumably while in a corner. I wonder if you are refering to a tip over switch designed to cut the ignition totally at no angle other than a tip over incident.

As your problem is related to spark...or the lack of one I would be checking the coil/s, ht lead, cap and plug. Also I would check to see what voltrage the coil is getting. If you have a cdi then it is very likely there is a problem there. Anything short of a fat blue spark can be considered suspect.

Also check all the handlebar switches are clean and functioning properly...I spray WD40 in to clear any crap out but it should be cleaned off afterwards.

Good luck
 

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Discussion Starter #3
I have never heard of a lean angle sensor...and wouldnt think it would lower the volatge as the lean angle increased...very dangerous since the last thing you want is the motor quiting while you are leaning over,presumably while in a corner. I wonder if you are refering to a tip over switch designed to cut the ignition totally at no angle other than a tip over incident.

As your problem is related to spark...or the lack of one I would be checking the coil/s, ht lead, cap and plug. Also I would check to see what voltrage the coil is getting. If you have a cdi then it is very likely there is a problem there. Anything short of a fat blue spark can be considered suspect.

Also check all the handlebar switches are clean and functioning properly...I spray WD40 in to clear any crap out but it should be cleaned off afterwards.

Good luck
Yea Steve that tip over sensor is a Lean Angle Sensor. It assumes you have fallen and cuts the engine ignition off. According to my readings at normal functioning of the sensor mine is showing 3-4volts and drops as it is moved past 45 degrees. I would think it would be at zero but there is not much data describing how these sensors work.

All the switches on the handlebar work my multimeter shows voltage as the switches turn on and off. The coil is brand new and the coil has voltage at the leads that connect to the primary and secondary. Not sure what the right amount of voltage is supposed to be but there is voltage. The stator is new as well. I think my next step should be to buy a new lean angle sensor and hope for the best that the problem isn't the ECU/CDI.
 

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Discussion Starter #5
Yes it has a battery and a jump starter attached. In my experience that stuff is never the cause of the issue. Well at least for spark, maybe for an engine not cranking it may help but I have been at this for a few days now and I don't want to throw money at it til it's fixed but unfortunatley I might have to since I only know one way of testing the lean angle sensor and I don't trust the results.
 

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Yes it has a battery and a jump starter attached.
Well that really doesn't answer the question.
With all your experience I assume that you have a voltmeter to actually test the batteries.

In MY experience, modern bikes will sometimes not produce a spark if the voltage drops too low while the engine is cranking.
Or to put it another way, the simple fact that it is cranking does NOT necessarily mean that the voltage is high enough to run the electronic ignition.

I am not insisting that IS the problem.......but it is really sad when something simple like that is overlooked.
 

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Easy to check the above....Is the tip over switch mounted the correct way up? Also you should be able to jump the connectors at the tip over switch to remove it from the circuit.

Good luck
 

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Discussion Starter #8
Well if there is voltage drop I'm not sure I can locate it. One thing I noticed is there is a starter circuit relay. It's a relay before the starter solenoid relay. When I leave the bike turned in the on position for several minutes the relay gets warm. I'm thinking maybe there is either to much resistance on one of those wires or there maybe a short to one of those wires I honestly dunno. I know according to the the crappy service manual it is not part of the ignition circuit however it does show that it is spliced into one of the ignition wires.<br>

Well the service manual doesn't say which wire does what so I would be guessing on which wires to jump but I'm pretty sure it's both outside wires and the inside is the common ground. The tip over sensor connector is all female so I will have to use safety pins I think I'll give it a try I'm just a little orries it may effect the ECU by jumping them tho.
 

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Discussion Starter #10
Well I replaced the tip over sensor and no spark. This bike has drained me of any hope. I have no choice but to remove all the wiring wrap and inspect all the wiring. I think to myself how did it temporarily spark for a few minutes and then vanish at first.

I mentioned the ECU because the ECU controls the spark. A new ECU is $200
 

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Well I replaced the tip over sensor and no spark. This bike has drained me of any hope. I have no choice but to remove all the wiring wrap and inspect all the wiring. I think to myself how did it temporarily spark for a few minutes and then vanish at first.

I mentioned the ECU because the ECU controls the spark. A new ECU is $200
you dont have to de-wrap the harness. Everything is color coded. Just have to check continuity with a multi-meter. have you checked voltage at the various bits? When you turn the key on everything lights up as it should? (the warning lights on the cluster) if they do you have power to the computer. next check there is power at the coil. one is a signal. one should have power when the key is on. if you have power, check the control wire. if it is fine..... have you checked the crank position sensor? And all the fuses are good? could be a loose connector, or a bad ground.
 

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Discussion Starter #13
I probably haven't defined myself well. Let me start over. I have checked every sensor or switch that pertains to the ignition system. I know the wiring diagram by heart now. I have checked the engine stop switch for voltage in the on and off position and it is good, I have checked the kick stand sensor, Main switch, main and ignition fuses, checked chassis and engine ground, checked ignition coil and replaced it with new one and ohms check out, crankshaft position sensor, stator reads good on ohms and is brand new, tip over sensor, spark plug new.

The wiring diagram has a specific ignition circuit wiring diagram page and actually walks through a step by step troubleshooting process and I'm wondering if I fried my ECM. Let me explain why. When re assembling the bike from bare frame up. I being a dummy in my haste assumed the electronic plugs would fit into their specific other connector. That is how most chinese bikes are so you don't screw up however this Yamaha has connectors that will interchange with others meaning I could accidentally plug the starter wire into the wrong connector such as the start relay connector. I figured this out when the bike wouldn't crank and the rear brake handle was heating up but now all the wires are exactly where they are supposed to be but I'm wondering if I damaged something though no fuses popped when I incorrectly installed the wrong connectors.

Then when I noticed no spark when cranking I removed the stator to check if it was grounded out internally and it wasn't so I put it back and I suddenly got spark for like 7 times of cranking the engine. I moved the scooter outside expecting to take it for a spin and boom spark disappeared on me :(
So I assumed I had a bad stator. When the brand new stator and ignition coil arrived nothing changed and ever since then I have been chasing my tail. And that is the whole story.
 

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ok. that helps. there should be a way to verify if it the computer. seems to me like you have a loose connector. or bad wire. but i would re-check all the sensors. i have gotten ones that died. oh, do the idiot lights come illuminate for a few seconds after you turn the key on?
 

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If the machine is not getting a spark and everything other than the ecu is showing as OK then all that is left is the ecu. On another forum I am on a member had a faulty connector pin to the ecu so that may be a possibility.

One other possiblitiy....a long shot....does the spark plug cap have a metal HT voltage supressor fitted. I had a Honda years ago that had this and failed to spark due to water conducting the spark to the head instead of the plug points....like I said a long shot. What sort of gear change does the bike have....is it like a conventional scooter at the left handlebar and twisted into gears using an auto clutch....perhaps a neutral switch is failing somewhere?
 

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Discussion Starter #16 (Edited)
First off thanks for the great replies really good ideas. So DivineChaos I read your post and realized where you were going with that question so I went and checked the dash lights because I'm assuming what you are getting at is if the lights illuminate then that is one of the signs that the ECU is working. I'm not saying it is a full proof test but it's a clue at least. I turned the ignition to the on position and the check engine light came on briefly for a second or two and then it went away. I'm assuming that is normal but at least now I can ask the guys down at Zumaforums if there scooters do the same thing.

Aussie Steve If you are talking about the little resistor that is on the spark plug between the spring and the little brass nut then I do have one but I'm not sure it is any good. Also this scooter doesn't have gears well it has a stationary gear for the back tire but it uses a CVT to transmit the torque.

I dunno why my text is blue but who cares. So earlier today when checking the dash lights I decided to attach the head light back on and the fuel tank and the all of a sudden the scooter started sparking!! However the spark didn't look all that healthy but at least it was sparking. So I am sure glad to see that. Tomorrow if I have time I will do some more investigating. Thanks a bunch guys I needed a different angle to look at this issue.
 

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First off thanks for the great replies really good ideas. So DivineChaos I read your post and realized where you were going with that question so I went and checked the dash lights because I'm assuming what you are getting at is if the lights illuminate then that is one of the signs that the ECU is working. I'm not saying it is a full proof test but it's a clue at least. I turned the ignition to the on position and the check engine light came on briefly for a second or two and then it went away. I'm assuming that is normal but at least now I can ask the guys down at Zumaforums if there scooters do the same thing.

Aussie Steve If you are talking about the little resistor that is on the spark plug between the spring and the little brass nut then I do have one but I'm not sure it is any good. Also this scooter doesn't have gears well it has a stationary gear for the back tire but it uses a CVT to transmit the torque.

I dunno why my text is blue but who cares. So earlier today when checking the dash lights I decided to attach the head light back on and the fuel tank and the all of a sudden the scooter started sparking!! However the spark didn't look all that healthy but at least it was sparking. So I am sure glad to see that. Tomorrow if I have time I will do some more investigating. Thanks a bunch guys I needed a different angle to look at this issue.
glad you knew where i was going. its the self test. glad to hear that there is spark. sounds like a loose connector or a bad wire somewhere. i suggest now that you have spark, that once its running (hopefully it will) to do the wiggle test. just like it sounds. start wiggling wires and connectors. I bet you gave a bad one somewhere. I just had to replace the connectors that attach to my coil.
 

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First off thanks for the great replies really good ideas. So DivineChaos I read your post and realized where you were going with that question so I went and checked the dash lights because I'm assuming what you are getting at is if the lights illuminate then that is one of the signs that the ECU is working. I'm not saying it is a full proof test but it's a clue at least. I turned the ignition to the on position and the check engine light came on briefly for a second or two and then it went away. I'm assuming that is normal but at least now I can ask the guys down at Zumaforums if there scooters do the same thing.

Aussie Steve If you are talking about the little resistor that is on the spark plug between the spring and the little brass nut then I do have one but I'm not sure it is any good. Also this scooter doesn't have gears well it has a stationary gear for the back tire but it uses a CVT to transmit the torque.

I dunno why my text is blue but who cares. So earlier today when checking the dash lights decided to attach the head light back on and the fuel tank and the all of a sudden the scooter started sparking!! However the spark didn't look all that healthy but at least it was sparking. So I am sure glad to see that. Tomorrow if I have time I will do some more investigating. Thanks a bunch guys I needed a different angle to look at this issue.
I would suggest it needs the headlight assembly along with the associated wiring harness so the ignition works.
 

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Discussion Starter #19 (Edited)
Well tomorrow is here and now it no longer sparks. So I am going to start the wiggling process at each connector junction I'll keep you guys posted.

As I was wiggling the connectors I noticed the check engine light flashing. I get 3 slow flashes and 3 fast flashes. I believe the slow flashes represent 10 and the fast flashes represent 1. So code 33
 

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oh the joys of tracking electrical gremlins. i have a truck that reminds me of that. fresh crate motor, rebuilt trans and transference. new computer. over 6k into it. but it has a wiring issue i cant figure out. its stuck in limp mode. ford and there 93 wiring. a manual will yell you the code. hope you find it.
 
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