I have a good quality "as far as china atv's go" china 150cc atv that's fully auto but has a strange problem I just can not figure out. One day when I turned the key on to start it for my daughter it acted like a dead battery and there was no power at the key, no neutral light lighting up and no lights. When you pushed the electric start button nothing happens. I checked the battery and its fully charged. The starter will work if you jump the solenoid and start the machine as long as the key is on. Once the atv is running the neutral lights work and all lights work fine and if you hit the electric start button "with pulling in the brake handle" then the starter will engage. Once its running everything works fine! You do have to pull in the brake lever to engage the starter so I know it has a safety switch. So I thought maybe it could be a safty switch but the brake light works fine and the everything works fine when running. It has a fuse in the solenoid and its good. If you turn the key on and use the kick starter it will start fine and then everything powers up. What in the world is wrong with this bike I am baffled can anyone help? I am so confused. I have had it 3 years and its holding up very well other then this problem.

 

did you check the wiring connections at the key switch to see if they're making good contact? sometimes the terminations become loose or the quick connect fitting(s) begin to come apart. dilectric grease will help also. good luck.

 

Yes I checked the key and other connections. The key seems to work fine it turns the atv on and off.

 

This is an easy problem, so rest easy... You can solve this...

At first read I was thinking this is just a classic blown fuse scenario. But I read later that you've checked the fuse, so we might have to look a little deeper. Here is what is going on with your quad:

There is a broken connection somewhere from the positive battery terminal, to the 12 volt power bus that runs everything that runs on 12 volts. Normally the positive battery terminal connects to the 12 volt bus through the fuse, and then though the ignition switch (which must be "on" to make the connection). To start up your quad using the start button and the brake switch safety interlock you need to have 12 volts on the 12 volt power bus. You obviously don't because nothing related to 12 volts works (lights, etc) when engine is off and the ignition switch is on.

But when you kick start the quad, or jump the solenoid (which manually connects the battery directly to the starter motor bypassing all switches and safety interlocks), the quad starts up. That is because your quad ignition system runs on moderately high voltage AC power generated in the stator. It's sort of like your lawn mower - you pull the rope which turns the engine, and it starts up. There is no battery on your lawn mower, or 12 volts anything involved here. The ignition power comes from the turning engine - not any sort of battery. It is the same with your quad. Turn the engine, and the ignition system starts working. It doesn't matter how you turn the engine (kick starting, or powering the starter motor directly/manually off the battery) the quad will start as long as the engine is turned somehow.

Ah, but there is a caveat. The ignition switch has two separate switches inside ganged together on a common shaft. One switches fused 12 volts onto the 12 volt power bus when the switch is "on" (well it is supposed to, anyway). The other switch shorts the kill switch input to the CDI to ground (killing spark) when the ignition switch is "off". The ignition switch therefore has to be "on" to get any spark - which you need for the engine to start (which you reported).

Again your quad isn't getting power to the 12 volt power bus (through the fuse, ignition switch, and associated wiring). But when your quad starts up (kick start, or jumping the solenoid) something magical happens. The stator also has another completely separate power generation scheme inside (besides the ignition power stuff). There are windings that produce low voltage and moderately high current AC power which is used to power all the 12 volt stuff so that the battery doesn't have to, and provide enough extra power to feed current back into the battery to keep it charged up. This AC power goes to the voltage regulator which converts the AC into DC power and regulates it to power the 12 volt power bus.

So once the engine is running - even though you have a broken connection between the battery and the 12 volt power bus somewhere- the 12 volt power bus is powered up via the stator and voltage regulator from the running engine. That explains why your starter and brake safety interlock works fine when on a running engine.

I hope this all makes sense . And I hope you see why I immediately thought you had a blown fuse. If you had a blown fuse your quad would act "exactly" like you described. But your fuse is good. So let's find out where your broken connection is:

1) Get a meter and set it to read DC volts on the 20 volt scale. Put the black lead on the negative battery terminal and leave it there for the rest of the tests.

2) Using the red lead of the meter to measure the voltage on the output side of the fuse (which I believe you said was in the starter solenoid). You need to have 12 volts here. Do you see this?

3) Find the wires feeding the ignition switch. There should be four of them. Use the red lead of the meter to measure the voltage on all of them. If you have to to, use a sewing pin to poke through the wire insulation to get at the copper conductor inside (and then put your meter lead on the sewing pin). One of these leads should be 12 volts all the time (probably a red wire - but maybe not). Can you find this wire?

4) There should be another wire at the ignition switch that has 12 volts only when the ignition switch is "on". Often this is a black wire, but this isn't a given. Measure them all. Can you find a wire that switches 12 volts on and off with the ignition switch?

This is a good starting point, and will give a lot of info to help solve this problem....

 

Well I agree that your key switch will turn the ATV "off". That is the kill switch part of the the dual ganged ignition switch that kills spark when the ignition switch is turned "off". That's only half the story for a working ignition switch. The other switch in the dual switch ignition assemby applies fused 12 volts to the 12 volt power bus. I see no evidence from what you report that this is happening. The measurements in my previous post should help determine whether this part of your ignition switch is working .

 

Thanks everybody it was the fused wire that comes from the solenoid and runs to the connections that go to the key switch. It was broken inside and could not be seen from the outside. I just cut the wire at both ends plugged in the connector and wired those 2 wires together and everything works perfect!

 

You were 100% right, Great advice!

 

I knew you could fix it... .

I'm glad it's running again .