My O-320 Won't Start

[Mel]

Originally Posted by Canadian_JOY

Wow, I haven't heard that one in a long time! Thanks, Mel, for refreshing my memory of some great "field fixes" shared with me by wise old mechanics years ago. I had completely forgotten about the "business card points file". You've put a big grin on my face with that memory!

Oops, Did I just tell my age?

[bill v]

my plane was slowly getting harder to start and then it would start when I let go of the key to stop cranking and then it started on both with the last turn off the prop. it was a worn impulse coupling on the left slick mag. I replaced the mag. my mag checks were good when running also

[Kent Ashton]

Not sure what triggers you have on the Lightspeed but a good check is to remove the plugs, lay them on the top of the engine and pass a screwdriver or magnet, depending on trigger type, over the triggers (with the ignition on). You should see strong white sparks at the plugs. That tells you the system is working, then you just need to confirm the flywheel-to-trigger gap is set correctly.

If you have a mag-hole trigger, remove it and twist the gear. Should fire the plugs.

[tim2542]

Does the magneto have an impulse coupler? If not is the mag switch configured to prevent the mag from firing during cranking?
Tim Andres

[Towline]

Thanks all!

So on investigation of the switch, the Plasma is connected to R terminal on the ACS and is therefore grounded on start, so we are trying to start on the Mag alone. The mag does have an impulse coupler so it stands to reason that this mag needs looking into as it is approaching 500 hours. We have reassessed the ACS Service Bulletin and the Inspector is signing that off again.

Next question is whether we swap wires on the switch so that the Mag is grounded on start and we start with the Plasma box, at least to fly her to a workshop and get the mag overhauled.

If you had a 1x mag and 1x Plasma system, which would you start on?

[Towline]

Originally Posted by bill v

my plane was slowly getting harder to start and then it would start when I let go of the key to stop cranking and then it started on both with the last turn off the prop. it was a worn impulse coupling on the left slick mag. I replaced the mag. my mag checks were good when running also

Did the impulse still sound okay (click) when you pass the prop through TDC?

[Tomcat RV4]

Boy , talk about great memory?s, business card or matchbook run thru points brings me back to 50s-60s working on VW Bugs !

[Sam Buchanan]

Originally Posted by Tomcat RV4

Boy , talk about great memory?s, business card or matchbook run thru points brings me back to 50s-60s working on VW Bugs !

And British motorcycles!

[lr172]

Originally Posted by Towline

Thanks all!

So on investigation of the switch, the Plasma is connected to R terminal on the ACS and is therefore grounded on start, so we are trying to start on the Mag alone. The mag does have an impulse coupler so it stands to reason that this mag needs looking into as it is approaching 500 hours. We have reassessed the ACS Service Bulletin and the Inspector is signing that off again.

Next question is whether we swap wires on the switch so that the Mag is grounded on start and we start with the Plasma box, at least to fly her to a workshop and get the mag overhauled.

If you had a 1x mag and 1x Plasma system, which would you start on?

In your initial post, you indicate that you validated each plug on the mag was firing while cranking. You also indicated that the engine only kicks back when starting on the plasma.

Basic troubleshooting: Fuel / Air / Ignition. You confirmed that you get spark on the mag plugs during the starting phase. You also confirmed that the plasma is problematic during start (kicks back - pointing to timing issues), therefore eliminate the plasma during troubleshooting and move on the next two elements - Fuel and Air. Not much sense continuing to troubleshoot the mag, when you have confirmed that it is sparking.

Not saying that the mag isn't your problem, but it seems low on the probability list for the "no start" condition," given the details provided in the first post.

Larry

[lr172]

Originally Posted by tim2542

Does the magneto have an impulse coupler? If not is the mag switch configured to prevent the mag from firing during cranking?
Tim Andres

Item 1 on bullet list