Engine dies when honking - Keeway ARN 125 By kancur (Read 1,384 times)

[kancur]

Hi everybody, I have a pretty interesting electrical problem with my Keeway ARN 125 scooter.


Problem 1: The scooter works nicely, but when I press the HORN button, engine dies for about 5-10 seconds, then it gets back to life and works OK. (I can't wrap my head around this one)


Problem 2: When I try to crank it using the electrical starter, the engine usually starts just fine, but works for only as long as I hold the starter button! As soon as I let it go, it dies. I can play with throttle and it responds nicely, but when I let off the starter button, it dies. Most of the time I am able to start the scooter this way in about 10 minutes of playing with starter and throttle, and suddenly it begins to work.


Problem 3: Sometimes the engine dies, but without any visible cause. It doesn't matter what speed I go or RPMs of the engine, it just dies for about 5 seconds and then starts working normally, until dying randomly again. This is not happening often. Usually the biggest problem is to get it to start.


More info: I tried checking all my ground connections (but they still might be the cause), moving with all the cables, but have not found any possible cause.

The engine runs no matter if battery is present BUT it has an DC CDI with only one +12VDC connection.


I've had problems with engine randomly dying few months back, but that was because of bad ignition coil, and it was resolved by buying a new one.


Sometimes it gives spark, sometimes not.
But what about it dying when honking or working only while holding starter button? What might be the cause?
I don't think it's because of the load. The light don't make the engine shutdown and definitely use more power. I measured the voltage drop when honking and it was about 0.1V. The horn works normally.

I find it difficult to diagnose because it sometimes works, and sometimes not. 
Thanks for any help! 

[cyborg]

Check all grounds ,,1st pull all plastics,,,all of them,,,start at the battery,,,check all terminations battery posts and battery to frame grounds ,,engine ground,,,then move on to the handlebar area,,,this is where I believe the problem lies,,,again check ground wires and all terminations,,,your probably going to find a broken or pinched wire or two

[kancur]

Thank you, I tried to find bad ground without any luck. It seems to work now, and it might have possibly been caused by bad DC connection to the DCI. But I have to make some test rides to see.

[lostforawhile]

check your pins, you may have to depin them and bend the tabs back, as they may have lost tension

[tvnacman]

I suspect, the main plug by the handel bars. The one that connects the harness to all the control switches. While I'm in there see if there is an alarm box in there. Could be a defective alarm or defective bypass for the alarm. Check the harness in that area for chafing. Hot/melted harness spots can cause very strange problems.
Pictures help a great deal, sometimes we can spot a defect in a pic that has otherwise been missed. Post full pictures that we can look around the area as well.
Please start with a picture of your stator and cdi plug. You say its DCI lets see for sure
John

[tomw]

The horn and starter button switches may be providing/removing a path to ground for the ignition. When there are bad connections, other things electrical can start to act funny. The starter button sends power to the starter relay, or it MAY provide ground for the starter relay coil winding. Either way, it may also be providing a ground path for the ignition. The horn may be grounding the ignition, as many horns are wired 'backwards', in that you ground them to make them work.
tom

[tvnacman]

Nov 21, 2017 12:26:58 GMT -6 tomw said:

The horn and starter button switches may be providing/removing a path to ground for the ignition. When there are bad connections, other things electrical can start to act funny. The starter button sends power to the starter relay, or it MAY provide ground for the starter relay coil winding. Either way, it may also be providing a ground path for the ignition. The horn may be grounding the ignition, as many horns are wired 'backwards', in that you ground them to make them work.
tom

Starter button provides ground for the solinoid, headlight switches power, not 100% for signals and horn. Two wire kill switches, side stand switches and tip switches provide ground.

John

[kancur]

Hi guys, thank you a ton for all your answers. It's pretty difficult to work on a scooter right now as I don't have a garage and it's cold and snowing outside . I thought several times that I found the cause, but it never is the correct one. I tried checking grounds, connectors - but I'm pretty sure I missed a lot of stuff. So definitely have to recheck that. 

It's hard for me to diagnose because it's sometimes working perfectly and sometimes not. For example the horn trick does not work now - engine won't die when honking. 

But now it has come to the point when I have this one persistent problem - that might help me find the real cause. 
It's the starting problem. Engine runs only as long as I hold the starter button (Seems like a ground problem to me). (After trying to start for like 5 minutes or maybe 10, it will suddenly start working without the starter button pressed and works ok, till the next stop, just a minute is enough and starting is problem again. Sometimes it just randomly dies too. )

Another thing is that it starts fine on first try, but I let go the starter button, it dies, and then it doesn't start. I have to wait for about 30 seconds to crank it because it doesn't fire at all. - This might possibly be caused by the spark plug getting soaked in the unburned fuel after the engine died? - If not, then I have no idea what might cause this unwillingness to start without a waiting period of 30 seconds or one minute.

I don't have a CDI photo right now. But I am pretty sure it is a DC cdi. I only have one 12v power cable connected to the CDI which gets juice as soon as I turn the ignition key. I even tried wiring it directly to + of the battery to see if there is any power delivery problem. But I only tried it on the stand and it worked most of the time with or withous direct connection so I don't really know. 

I think you already advised me plenty of useful ideas, so I should definitely recheck all connectors and grounds and I will let you know then. I'm not sure when the weather will allow me to do that.

Thank you guys for all your help! :-)

Here is a photo of the front where I suspect the problem lies.

[cyborg]

You definitely have an electrical issue,,,my money is on a connector in the harness not snapped together properly

[kancur]

Ok, I spent the whole day trying to figure out what's wrong. I tried wiring the CDI +12V and Ground directly from the battery. Made no difference. (The scooter miraculously worked fine for an hour during the day when I was working on it, which made me frustrated because I changed all the cables back to original and it still worked. Then it stopped working later during the day.)

When it was not in a "running" mood. Wiring +12V ground and even spark output to the COIL directly made no difference.

Now it's evening and situation is like this:

It usually only fires the first spark. Or first two, but first one is always the brightest. Then during cranking, it occasionally makes a spark.

Sometimes it starts - and works for 10 seconds nicely - than dies without warning.

That made me think that maybe I have two problems instead of one. Could this be a sign of bad CDI or bad ignition coil (I'm on my second one as my first failed this year with similar things happening - the engine dying randomly.)

The strange thing is that it's still not working when wired directly from battery. (When it was miraculously working during the day, it worked with both original connectors or my direct wires to the battery.)

This means that the main problem should be between magneto, CDI and ignition coil. I had the magneto cover fan and rotor down today (I forgot to take a photo). I was testing the spark by moving a screwdriver in front of the hall sensor and it worked flawless with strong spark. Then I assembled it and it was working perfectly. Till it stopped working later during the day without any visible reason.

Thanks for your help!

Here's a photo of my CDI:

[tvnacman]

maybe the pick up coil is intermintent

[kancur]

tried a new ignition coil today. No change at all.. might try taking a more thorough look at the pick up coil.

EDIT:

Ok, I plan to do this now.

Wire CDI directly from battery +12V and ground.
Ground engine directly to battery. 

I've already done this but I will try once more. If it still doesn't work that leaves several options:

Bad CDI - how could I diagnose it?
Bad pickup coil or ground or signal from pickup coil.

Connection to the Ignition coil is already made new and should definitely be fine.

I'm pretty lost, but will try to play with it some more and come up with solution.

[cyborg]

Could be a bad cdi module,,,the erratic symptoms makes me think it’s that

[tomw]

If you want to be sure you have a DC CDI rather than the more common AC version, kick the engine over with the battery disconnected, and a spark plug stuffed into the plug wire, sitting on a grounded spot. A DC CDI requires the battery to be connected, as it runs on DC from the battery. An AC CDI will fire using the current produced by the alternator behind the cooling fan(commonly called the 'stator') as you kick the engine over. Simple and fool proof test, I think.
That said, when it will not start, the first thing to do is check if you have spark or not. It is likely spark is gone, given the way it is so intermittent. If a DC system, check for battery voltage on the connector on the CDI. One should have battery 12v with the key ON. The trigger by the flywheel will send a pulse that will cause the CDI to cut voltage to the coil, and when the voltage goes away, the field generated in the coil primary(lo volt) windings collapses, and generates electricity in the seconday, sent to the plug. No volts, no spark.
Given the low cost, a spare, known good coil, pickup, and CDI seem like a small investment to be able to figure out which one is cutting out. It could be the wires to the ignition switch(key switch) are chafed, or have semi-broken conductors, cutting the 12V to the CDI. Put a meter on the CDI 12v connector, and wiggle all the wires leading from the ignition switch.
tom

[kancur]

Thank you guys for all your advice, issue is still unresolved and the temperatures outside below freezing so I will probably not work on the scooter during holidays. I ordered new pickup coil and CDI. It will take a while for it to arrive from china. I will let you know once I test it.
Thanks