038AV stumped

[redram06]

hello all, looks like i found the right place for help.
working on a 038av for a friend and im stumped on why it won't start.
ive installed a kit in the carburetor (after thorough cleaning more than once) and replaced the feed line from the tank. the spark is good and after re-checking carb it's clean and has fuel in it when disassembled. it just doesn't seem to be getting fuel to the cylinder. the boot from carb to cylinder looks good from what i can see without removing completely. i'm now wondering if it has sheared the flywheel key and timing is off.
any help and suggestions would be greatly appreciated since i don't have much hair left to pull out.

 

[merc_man]

Will it try to start if you squirt mix in carb? If not i would pull muffler and look for scoring.

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[Sagebrush33]

hello all, looks like i found the right place for help.

You are correct.
Welcome to the site. Your 038 issues will get sorted out here.
Lots of knowledgeable guys here.

 

[Stump Shot]

hello all, looks like i found the right place for help.
working on a 038av for a friend and im stumped on why it won't start.
ive installed a kit in the carburetor (after thorough cleaning more than once) and replaced the feed line from the tank. the spark is good and after re-checking carb it's clean and has fuel in it when disassembled. it just doesn't seem to be getting fuel to the cylinder. the boot from carb to cylinder looks good from what i can see without removing completely. i'm now wondering if it has sheared the flywheel key and timing is off.
any help and suggestions would be greatly appreciated since i don't have much hair left to pull out.

To tell just what is going on with your spark/fuel situ, after a failed attempt to start with no fire, pull the spark plug and inspect it. If it's drenched in fuel, then you have a spark problem. If it's bone dry you have a fuel problem.
Never a bad idea to pull the exhaust cover and inspect the piston as mentioned, can save time or give confidence one.

 

[redram06]

To tell just what is going on with your spark/fuel situ, after a failed attempt to start with no fire, pull the spark plug and inspect it. If it's drenched in fuel, then you have a spark problem. If it's bone dry you have a fuel problem.
Never a bad idea to pull the exhaust cover and inspect the piston as mentioned, can save time or give confidence one.

 

[redram06]

thanks stump, i pulled the screen to see if it was plugged but not the whole muffler. i'll try that next. the plug is dry and thats why i concentrated on the carb but it seems full of fuel when taken apart. it does seem to have good compression although i haven't hooked the compression tester yet. i'll do that also. could the flywheel be sheared and cause it not to pull fuel at the proper time. thanks for the input

 

[redram06]

Will it try to start if you squirt mix in carb? If not i would pull muffler and look for scoring.

Sent from my SM-G950W using Tapatalk

thanks merc, i did put fuel in the cylinder and it still wouldn't hit

 

[Stump Shot]

thanks stump, i pulled the screen to see if it was plugged but not the whole muffler. i'll try that next. the plug is dry and thats why i concentrated on the carb but it seems full of fuel when taken apart. it does seem to have good compression although i haven't hooked the compression tester yet. i'll do that also. could the flywheel be sheared and cause it not to pull fuel at the proper time. thanks for the input

If the flywheel key is sheared(which can happen, but not often) it affects the spark only. The piston porting controls the incoming fuel charge.

thanks merc, i did put fuel in the cylinder and it still wouldn't hit

Now I really say take a look at that piston as well as the cylinder wall on the other side for clues.

 

[merc_man]

thanks merc, i did put fuel in the cylinder and it still wouldn't hit

Next step is pull muffler to have a look for scoring.

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[Maintenance Chief]

Impulse line blocked or cracked?
Spring in the ignition lead disconnected?
Kill switch ground wire bare?

 

[davidwyby]

I’m no pro.

If fuel is getting to the carb, the impulse must be working at least somewhat.
Perhaps something plugged or stuck in the carb.

 

[Canadian farm boy]

The choke is part of the air filter and are a known problem. If the filter isn’t seated 100% properly or if lever on the control rod is worn or damaged the choke won’t work and you’ll pull your arm off trying to cold start it.
The choke in the air filter is definitely a problem with the aftermarket filters. I don’t think I’ve seen one that actually works properly. The choke in the oem filters works much better.

 

[Big_6]

Check the diaphragm condition
and the lever height to assess the fuel delivery.


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[redram06]

To tell just what is going on with your spark/fuel situ, after a failed attempt to start with no fire, pull the spark plug and inspect it. If it's drenched in fuel, then you have a spark problem. If it's bone dry you have a fuel problem.
Never a bad idea to pull the exhaust cover and inspect the piston as mentioned, can save time or give confidence one.

Stump Shot, i realized i didn't have the filter on and was losing the choke mechanism. installed it and did get a "want to" hit from the engine. i pulled the muffler completely and there is a lot of scoring on the piston . i'm wondering now if there is a ring stuck or further damage to the cylinder that's affecting starting. did get some fuel on the plug after installing the filter. got some fuel and good spark. any suggestions? thanks in advance

 

[davidwyby]

Pics thru exhaust port.
Compression test.
Or just pull the cylinder.

 

[Maintenance Chief]

Tear down, and rebuild required now.

 

[Stump Shot]

Stump Shot, i realized i didn't have the filter on and was losing the choke mechanism. installed it and did get a "want to" hit from the engine. i pulled the muffler completely and there is a lot of scoring on the piston . i'm wondering now if there is a ring stuck or further damage to the cylinder that's affecting starting. did get some fuel on the plug after installing the filter. got some fuel and good spark. any suggestions? thanks in advance

You can forget the compression test as you have found your problem. Yes rings are most likely stuck and/or riding over aluminum transfer on the cylinder.
My suggestion is to hang it on the wall and leave it be, as there are a plethora of much better newer machines that are lighter and faster to use that parts are readily available for.
However if you are set on repairing it, the saw will need at minimum the cylinder cleaned up or replaced, a new piston and ring set, new spark plug, base and exhaust gaskets. That will get you to square 2. To get to square 1 the saw will need a pressure vacuum test to find any leaks that caused the damage to begin with. Also check gas for color of oil if it's gin clear then it was straight gassed and fuel needs removed and fresh put in. Then when you get the cause of the failure repaired the saw will need to be tuned before service.
Best of luck going forward.