SonexBuilders.net

So I went for a first startup today, but it would not start. There is a list of things to check via the AeroVee manual, and I will start going through those, but just wondered if others have had the same situation so maybe I can narrow down the culprit. Here's how it went:

- Went through the checklist.
- Fuel was on (5 gallons in the tank).
- Master was on.
- Mags/coils were on (at least the switches were on; I will of course need to check if they were indeed "working").
- Mixture full rich.
- Throttle 1/4".
- EFIS was on.
- Push starter button.
- Engine turned over nice and strong. Battery had 12.6 volts showing.
- Manual oil pressure gauge showed 40psi
- Engine never caught; never even sputtered. Acted like there was either no spark or no fuel.

- Fuel was coming out of the Aeroinjector (carb). It was not a lot. When I got out and looked at it after the failed starts, with the fuel ON and the mixture full rich, the fuel was dripping slowly from the carb. I have not yet done a fuel flow check, so maybe there's an issue there? I have the fuel tank finger strainer, but also an 80 micron fuel filter downstream.

So what's a good way to check if I'm getting spark? Do I pull the plugs, turn over the engine and actually look for spark? Or is there a way to check what's going through the spark plug wires without removing the plugs? Electronics are still voodoo to me.

I understand the basic workings of an engine, but I'm no motor head.

Thanks,
Mike Smith

Mike
You should have 12 volts at the primary of your secondary coil with the ignition turned on. You can check this with a DC volt meter. I would also check all of the wiring between the secondary pickups and the ignition coils. Make sure you timed the secondary by the Sonex instructions. The Aerovee may not start on primary only,

If you think you may have flooded your engine, you may try starting it at full lean on the mixture. If it fires you start pushing the mixture in. This method usually works on a flooded engine.

Cliff Evans
Sonex 674

Hey Mike,

You're not the first...we'll figure it out! Some thoughts right off hand:

- Pull the prop through by hand. Is there good compression? The prop should be difficult to pull all the way through and you'll hear air hissing. If not, there may be a timing issue (I feel for this one!)

- You said the mixture was full rich and you were only getting a few drops out of the carb? That doesn't seem like much. Where was the throttle? What happens when you push the throttle in all the way? It sounds like very little fuel was actually going through the AeroInjector...this may have been your issue.

- Where your your AeroInjector carb needle? Do you have it oriented correctly? Remember, the flat side of the needle faces the engine. A lot of people have had that issue.

- Last thing is to check for spark. I'd check voltage and then if you want, with the plugs removed hook a top plug up and lay it on the head, then hit the starter. You should see the spark.

I'd check those things over and let us know what you find out. Hang in there...you've almost got it!

Good luck!

I won't disagree with Mark about his comments about fuel and compression, but I would check spark first. With marginal compression and fuel, you should get something, even a cough, if you have spark.

My first turnover was a failure as well. I checked spark and found that setting the trigger magnet per the manual was too advanced to get spark. I retarded the spark quite a bit and it fired right up. From there it was pretty easy.

I think I found the problem! Like I said, electrical systems are not my forte... What I found was that I had wired the switch for the coils wrong. So wrong, in fact, that I wasn't actually providing any power to them!

http://www.mykitlog.com/users/display_l ... 8710&row=1

The first photo is the Sonex wiring diagram. Note that the switch is just a gate for the power.

The next photo shows what I did (all I did was ground the coils). I was thinking: "OK, I have a switch. One wire comes in, the other goes to ground." Nope! The coils themselves are grounded. I needed to provide power!

So my two options are on my Kitlog page in photo 2, with Option A coming from the master electric relay. That is easier for me to accomplish, but it means if I turn off the Master switch then the coils have no power going to them, though the primary/magneto system should still fire their plugs.

Option B is if I wire the switch directly to the battery (+) side, I already have 3 wires coming off that terminal, so it's getting rather crowded.

Opinions are welcome.

Mike

Mine is like option A. The master switch must be On in order for the ignition to work. The concern of course is that if you have a master solenoid failure the electronic ignition will not work. I consider the electronic ignition a "backup system" and often fly with it shut off.

radfordc wrote:Mine is like option A. The master switch must be On in order for the ignition to work. The concern of course is that if you have a master solenoid failure the electronic ignition will not work. I consider the electronic ignition a "backup system" and often fly with it shut off.

Or I could wire it to the hot side of the master relay. I have enough real estate there (only 1 wire there) , and would be the same effect as connecting it straight to the battery. My cockpit switch is a combination breaker/switch.

Mike

I wired mine to the hot side of the master relay as well; used a 10A inline fuse though. That way, I can shut off the master if need be and still have secondary. I figure that if I have something going on that requires killing the master, I want everything else I have going for me!

Carl

I have a friend who Bought a Sonex that needed some repair to the arframe and then thenengine. He flew it for a few hours and then had someone do an engine overhaul. He reinstalled the engine and it will run on the magnatonsnbut shutsdown when he switches to the secondary ignition. He is quite frustrated. Any sggestions? Thanks

My Oex is now completed but I have t sell my T51 in order to get it in the hanger.

onex28 wrote:He reinstalled the engine and it will run on the magnatonsnbut shutsdown when he switches to the secondary ignition. He is quite frustrated. Any sggestions? Thanks

Make sure the coils and spark plug wires are connected the correct cylinders.

Other than that, the Aerovee manual is really good. Make sure he has read the section on the secondary ignition.

http://www.aeroconversions.com/support/ ... Manual.pdf