Petrol blower start / kill question.

[ipbr21054]

Unable to start this Mc Culluch petrol blower.

I’ve taken the engine case off & see that 1 wire is off the kill switch. This shouldn’t be the cause of it as this only kills the engine correct ?

So I have removed the switch thus having 2 wires, one goes to the engine earth & other disappears into engine case.

My understanding is when you want to kill the engine by pressing the switch the earth then makes a circuit with the wire that disappears into engine case & say kills the coil so no spark is present. When the switch is in the on position the circuit is broken thus allowing spark to be present & allows starting of petrol blower.

Using a multi meter I’ve done this.

Connect each multimeter lead to each of the 2 wires that fit to switch. My multimeter beeps so circuit made.

Connect each multimeter lead to each switch terminal & no beep, operate the switch & beep.
So this tells me the switch is fine. I have a press on / off switch & also a press & let go type switch. The beep works & dies when it its supposed to.

So the above so far tells me all is ok.

Now I connect the 2 wires, engine earth & the other that disappears into engine case to the 2 terminals on the switch. I get a continuous beep.
I operate the switch many times BUT beep still present.
This tells me why the blower won’t start as it’s made a circuit & has killed the coil so no spark & trying a few times naturally floods the engine.

Now the question is why is a circuit made when I connect the 2 wires to the switch ?

 

[Burnerman]

Is the switch you have there a spring loaded one - press to kill the engine?
There should be no continuity there.
If it's a usual rocker type, one way means continuity, the other way no continuity.
Always test switches off the engine.
You are correct, one wire connects to the igniter coil, the other to a metal earth somewhere.
John

 

[ipbr21054]

I have both.
Rocker On / Off & also press to kill.

Can you explain why ?

Rocker switch tested off engine & does what it should do uising multimeter.
Press to kill shows no continuity when switch AS/IS but when i press the switch i then get continuity.

Either switch when connected with the 2 wires on the blower shows continuity straight away.
So rocker switch i het beep when in off position so i flick the switch & i still get beep.

Is my test to leave switch disconnected thus 2 wires just dangling & not touching anything & see if it will start ?
I understand i will need to apply choke to kill engine.

 

[Burnerman]

Your multimeter is sensing continuity through the igniter coil - hence my reasoning to always test the switch off the engine. There will be a resistance there but I'm not sure how much.
Either switch will do - they are both working.
Million dollar question - are you getting a spark at the plug with the switch disconnected?
If the engine starts, full choke will stop it again.
John

 

[ipbr21054]

Switch was tested OFF engine & works fine.
I was saying when i connect wires from engine to switch i get beep all the time.

How does multimeter sense from coil when switch in off position.

Anyway now rain has stopped i will go check

 

[Burnerman]

Lets go back to your first post......one wire was not connected to the switch. I'm wondering why - unless it just vibrated off or is it hiding something?
Maybe there is a bare wire somewhere which is shorting things out?
John

 

[ipbr21054]

Striong spark with & without switch installed.
I screwed both screws on the carb in & started to wind them out both at the same amount of turns.
Go to say 8 tuens out & it spluttered as it going to start but didnt.
I continued untill it should of started somewhere within my range out all the way in to pretty much all the way out.
Nothing so ive geiven up & going to look for another.

Thanks for your time with thus but i wasted 1/2 a day today trying to solve this

 

[Burnerman]

No problems from this end, but those screws need to be set at about one turn out from fully in.....
Much more than that and the result will be over fuelling by a large degree.
With any two stroke machine, my motto is if there’s good compression it will run again!
John

 

[ipbr21054]

Just didnt want to do anything from way out.
Now im looking at the gearbox return lever on my other post