Columbo

My Feedback: (9)

My ignition on my 3W75 appears not to be working properly, and as a result the engine won't start. I placed the spark plug in the plug cap and noticed it will spark as soon as I turn the on/off switch on, but when I quickly flip the prop, there is no spark. Is it normal for the ignition to fire as soon as you turn the switch on? If not what will cause this.

Thanks in advance,

Greg

Columbo

My Feedback: (9)

Hmmm,

After reading a couple other posts on a similar topic it sounds like the sensor could be bad and propably not the ignition since I get a spark when the switch is turned on. My question is, what is the most likely cause for a sensor to go bad?

Anyone?

Greg

Dan767

My Feedback: (19)

I have a 3W-75i. It doesn't spark when I turn on the ignition, but it does when the Hall sensors pass. Very bright. Using a 4.8v 1100mah pack. I have the new module for the tach. What little experience I have with mine, I have learned that mine floods very easily. It was also very difficult to start until I got the needles close to where the engine would run well, but that might have been my technique. Pull the plug and see if it's wet. If it is, dry it off, replace. Choke, open throttle just a few clicks. Pull it through until it fires. Close the throttle, open the choke and it should start in four or five flips. Mine will. I have only about a half gallon through mine. I learned on friday that I neglected to tape my hall sensor connectors together. Dead stick, tore out the gear.

Columbo

My Feedback: (9)

Thanks Boeing 767.

The procedure you described is how I normall start it. The engine isn't flooded, and I even used a new spark plug. When I normally turn the prop with the plug in the spark cap but out of the crankcase, I get a spark. There is something going wrong with either the ignition, the spark cap or the sensor. I will probably just have to send it back in for testing.

Greg

Geistware

My Feedback: (16)

Remove the plug so that the propeller can freely spin.
You shold get a spark when the magnet passes the sensor.

Columbo

My Feedback: (9)

Geistware,

That's precisely what I did. It only sparks when I turn the switch on.

Greg

TLH101

My Feedback: (90)

Greg,
Not sure if this will help, but i have several engines with C&H ignition, and when a pick-up sensor goes bad, the symptoms are exactly as you describe. Only a spark when switch is turned on. If the 3W ignition is built similar to C&H, that could be your problem.
Take it for what it is worth, hope it's some help.

Kris^

My Feedback: (1)

Columbo, try to hang a hobby knife from the magnet in the engines hub. If it will hang from the blade, the magnet is good, if not, you will need a new one. Just rotate the hub so that the magnet is on the side, and lay the blade of the knife on it. . it should have VERY strong pull and the blade should hang from it without slipping. If this does not occur, replace the magnet.

Second check is to Ohm the pickup itself. The range of resistance I have for 4 3W pickups in my possession, as well as 2 DA pickups, is 235-315 ohms, so I'd say that between 200-350 ohms of resistance is the acceptable range. Outside of this range, I'd replace the pickup.

If both of these components check good, and you are sure you have proper voltage to the ignition box, you have a bad box. .it's that simple.

Columbo

My Feedback: (9)

I have checked magnet. It is very strong. The only thing I haven't checked is the resistance on the pickup. I will do that today.

Thanks a lot guys!

Greg