Ignition Gremlin

[Dusty]

I havn't checked the trigger coil gap,they have been replaced with the later type.
We didn't realise at the time they were adjustable
The engine hasn't been run since then.
My engine also has the paired earth wires on the coils,this will be changed.

[mr bill]

The old style coils were not adjustable, but the new ones are.

[Paul Z]

According to the Heavy Maintenance Mannual both the old and the new are adjustable. 74-00-00 page 50 shows the potted style, while page 51 shows the newer style. I have never seen or worked on the old ones, but I'd at least check the gap.

[Av8r3400]

If you look on page 47 of chapter 74 in the Heavy Maintenance manual you will see that the "old" style are not slotted or really adjustable.


The old style pickups should be .016-.020" (.4-.5mm), the new should be .012-.016" (.3-.4mm).

[ref Chapter 74, page 62 Heavy Maint. Manual]

[Paul Z]

Good luck.

[Dusty]

Thanks for the link for the maintenance manual,very helpful as our local rotax expert was not available to do this rework for the next week.
The wiring diagram for the 6 pin module/4pin pickup is the one I need.
I intend to get back to the hanger later this week to finish,check and ground run.
My triggers are the type with a guide collar and no significant adjustment, but I will still check the gap.

[Dusty]

Update
I moved the modules (a pair of borrowed and good ones)to the cabin .
The coils are in their original location,so an extension lead was made to connect these to the modules.Right from startup was a definite improvement.
6 hrs flying apart from a couple of minor stumbles on takeoff all good.
I still don't know the source of the original problems but definitely a broken pickup wire. I had paired earths on the coils maybe another problem?
The next step after some minor tweaking and checking is to fit my original modules one at a time to see if these are good.

[Dusty]

Another 5 hrs and all good,the brief stumbles were still there which we are putting down to carb ice (autumn here mild temps high humidity)this may have been aggravating the broken wire misfire,but this has been sorted now, I will start a separate thread to cover the fix for this.

[DesertFox4]

Dusty, do you have the newest fuel pump on your 912 yet? When the old style acts up it behaves like you have described or drops out completely.

Here is a pic of the new style except this has the very expensive fitted hoses.
The new pump with just barbed hose fittings is about $100.00 from L.E.A.F.

image.jpg

[Dusty]

Yup
That's the pump I have,rock steady 4.5 ibs pressure,even tried a piersberg? Have tried an electric boost and even a regulator.The fuel filters and lines have been changed and flows checked.
Hopefully we have eliminated fuel as a suspect.