Scooter blowing fuse

[Richard O.]

Hello I am new on here this is my first post I am Richard O.
I have just bought 50 cc A 2009 model Motofino scooter and worked on it a little bit and got it running really good then the next day I went to ride it wouldn't start the battery was in good shape but the starter wouldn't turn over I checked the fuse and it was blown so I replaced it and it blue it out too I checked all of the wiring for shorts and can't find any but I did fine if I unplug the two wires that attach little coil at the end of spark plug wire then install the fuse it don't blow it out can any body explain that to me please help!!!

[Shadowfire]

Most likely -> wiring to/from the coil (or some of the other wires bundled with it) is damaged and shorted to the chassis (or each other), and moving the wire has (temporarily) stopped the wire from contacting the chassis.

Less likely -> Something on the coil assembly itself shorted to the chassis.
Look for damaged insulation/broken plastic on the coil, especially where its attached to the frame. Check the wire leading to the spark plug too.

It's also possible (but extremely unlikely) that the coil itself has an internal short.

You're basically looking for anything wire that has exposed metal which could short out, probably with the frame of the bike.

[Richard O.]

thank you shadowfire I have looked everywhere but can't seem to find it I can unplug the coil from the two wires and the short is gone it does not blow the fuse makes me think maybe the coil has a short I am going to give it another going over maybe I'll find it this time thanks again

[blueboy5000]

Trace the green wire on the coil, that's ground. Make sure it's intact.

If it is, replace coil.

[Shadowfire]

A break in the ground wire would cause the engine to stop firing, not a blown fuse. He is definitely looking for the hot wire (or spark plug wire) shorting to the engine block or chassis.

Another thing to consider is the spark plug. You should not have any continuity between the spark plug clamp tip and the engine frame, there should be an air gap.

[blueboy5000]

A break in a ground will indeed cause fuses to blow. In fact, bad grounds are the #1 cause of fuse failure in all DC systems.

Stating that a bad a ground will not blow a fuse is incorrect.

[Richard O.]

Well I thank all of you for the information you posted I took all the skin off of it and unwrapped the wires where they had them all wrapped together I did find where they had soldered some green ground wire together and then taped it but I didn't find any shorts anywhere where I bought this unit it was used as a parts machine for other new bikes but he had received all new parts for the ones he had taken off I bought the bike and got all of the new parts and I brought it home put everything back together again and it ran just like a new one after I done that then the next day it had this short and I can't find it if I put a new fuse and plug the two wires to the coil the coil starts to get hot and then blows the fuse So does anybody have any idea what the problem might Be it sure has me dumbfounded

[stitch_man87]

You need to find someone with a voltmeter and a somewhat extensive knowledge of auto/cycle electronic systems if swapping a couple parts doesn't fix it. A little knowledge can do a lot of damage...

[Shadowfire]

OK. You provided some good additional information in that last post.

First thing to check is...

Is it possible that you swapped the two wires leading to the coil?

If they're keyed somehow and you can't make this mistake, then it sound like the ignition module (CDI) is toast, and is driving the coil 100% of the time. It should only drive the coil briefly when it sees a pulse from the stator timing coil.

[Richard O.]

Yes that is the next thing I plan on checking is the stator coil I have never dealt with a cdi and a small coil on the end of the spark wire how doe's a cdi work ! when I got the bike I got several coils and cdi modules with the bike they are new but have different numbers on them I will check the stator later thanks for the information

[Richard O.]

OH! the wires to the coil are one green and one yellow and the coil has green on one terminal so I put the green wire on that one

[Richard O.]

also I did check the hot wire to the and it showed power all of time on my volt meter but I didn't turn the engine over and check again but now I will do that

[bull]

Most likely during your install of the parts you shorted a circuit. You should buy a 12Vdc circuit (power / logic) probe and a digital multimeter. You can buy them from Harbor Freight rather cheaply and in this thread I show you the ones a non professional mechanic should own.

http://www.scootdawg.net/showthread....467#post534467

If the main fuse is blowing, it tells you that you are pulling too much power through it and it burns out to protect the circuit. That cheap meter can handle up to 10 amps flowing in a circuit before its internal protection (fuse) blows.

Go to the local auto parts store, buy a cheap inline ATO or ATC fuse holder, get some low amp fuses like 5 amp (cause you will burn out a bunch of them). Connect the inline holder across where the original fuse goes, disconnect the scooter ign switch, stator and regulator, then install a fuse in the new holder--

Did it burn out right away?

[Richard O.]

I did what you said to do and the fuse didn't blow but when I unplug the key switch I no longer had power anywhere I can remove the CDI and the also the stater and still have power to the coil wire without coil hooked to it

[bull]

Originally Posted by Richard O.

I did what you said to do and the fuse didn't blow but when I unplug the key switch I no longer had power anywhere

This would be a normal expected condition and the way to perform proper testing.

Keep the stator and regulator unplugged, reconnect the ign switch w/ key off- does the fuse blow now?

If no, then turn ign switch to on, but not running, did the fuse blow now?