Stihl 038 AV ignition/stalling issues

[MitchellCustoms]

I have an 038 AV Magnum II giving me all sorts of headache.

New spark plug, new fuel line, cleaned up ignition coil armature & magneto on flywheel, re-gapped at about .010/.012" (folded printer paper over 3x)...

Difficult to start (always has been) gotta go between full and half choke, then hit the throttle to catch an idle.

Stalls/cuts out at 3/4 to full throttle with brake off and chain spinning.

Replaced fuel line today as the old one had a few pinholes before it hit the carburetor, figured that was the issue...

Thinking maybe it's the coil going bad? Is there a way to test it on the bench with a multimeter? If so, what are the desired values?

Thanks ahead of time for any input or suggestions...

 

[Ozhoo]

Welcome to AS. 038's only weak point is that cheesy choke flap in the air filter. Verify that flap is closing for starters. What are your carb settings?

 

[MitchellCustoms]

I'll double check on the choke flap, pretty sure it's working fine. Cleaned the air filter a few days ago, everything seemed ok.

Only fiddled with carb settings to get a better idle... What would a good starting point be if I reset/re-do carb adjustment?

 

[Ozhoo]

1 turn out on both high and low. If you're not somewhere around that, then you got other issues.

 

[HarleyT]

If you had holes in your fuel line, then your carb is full of crud.

 

[Wood Doctor]

Carb issue as HarleyT said above. The clue is this sentence in your post:

"Difficult to start (always has been) gotta go between full and half choke, then hit the throttle to catch an idle."

I suggest that you either rebuild or replace the carb. I usually replace them but some guys here like to rebuild them. One other thing: that impulse hose may need replacing. I know that's a PITA, but it's worth the effort, and you can use ordinary Tygon fuel line for that.

 

[Mad Professor]

Pull the covers on the carb and check the rubber diaphragms and the mesh fuel filter. Most times if they look good the carb is O.K. Sometimes the pump side coveris just loaded up with sawdust, it gets in through the vent hole.

Make sure the wire in the sparkplug end of the coil wire is O.K. and also inspect the wire where it passes the tank housing. If the AV rubber is tired it can pinch the wire there and you may miss a short there. Some liquid electrical tape a a few wraps of tape will fix that.

One other thing if it just stumbles as you throttle up you may need to ricthen the low screw.

 

[GPX433Todd]

Grub screw tank vent?

 

[Wood Doctor]

...
Make sure the wire in the sparkplug end of the coil wire is O.K. and also inspect the wire where it passes the tank housing. If the AV rubber is tired it can pinch the wire there and you may miss a short there. Some liquid electrical tape a a few wraps of tape will fix that...

I ran into this with a Stihl 028 Super. A repair shop had re-assembled the saw by squeezing the plug wire against the cylinder fins using the shroud. When the hot engine ran, it eventually burned through the insulation and shorted out the spark.