Stihl 034 flooding.......CONSTANTLY.

[Scotty Overkill]

Heres a quick run-down on the saw....

I rebuilt the saw from a box of parts around 14 months ago. AM piston, Hy-Way nickasil cylinder, Caber rings, new crank seals when rebuilt. Saw ran pretty well, only mods were a slight timing advance and a muffler mod. Nothing else. It did break a set of rings when i first rebuilt the saw thanks to a lousy casting on the exhaust port, I fixed the port (amazingly no damage to the P/C) and replaced the rings, ran perfectly fine. Was a reliable saw, great for bucking tops.

Ran the saw flawlessly up until this past August when I had to buck a top that landed in a deep creek. I sat the idling saw on the log after making a cut to catch a floating runaway round, and the saw slid off the log into the creek while running.
Drained it, and let the saw dry out, and it would run, but was really finicky. Then, after using it a few times afterwards, it quit altogether. I figured maybe it sucked water in and pushed the seals out, so I parked it.

Three weeks ago I tore it down, and sure enough the flywheel-side seal was pushed out and into the flywheel. I pulled the seals, pulled the jug to check for damage, replaced the fuel line while it was down, replaced the carb (original one was beat up pretty bad), installed new crank seals on both sides, replaced impulse line, replaced the coil with an AM version, and ported the cylinder and transfers mildly while it was out, did a base gasket delete, and put it all back together.


Had it running a couple time this evening, but the bastage shuts off like a switch out of nowhere, so I pull the spark plug and find it wet-fouled....and it does it relentlessly, over and over again....I had it running long enough to get the carb tuned pretty good, so I'm pretty much ruling the carburetor out.

Should I closely inspect the crankcase gasket? I pretty much did everything else to this damned thing, I'm fixing to give it a good toss here soon.....lol

Any idea fellas? Thanks in advance.....

 

[Chainsaw Jim]

I wonder if there is corrosion somewhere in the spark plug wire causing a short.

 

[J_M____]

Coil or plug. I have had new plugs once hot expand enough to somehow short internally, must be a crack in the insulator. Try a known good plug, then try another coil. Bad coil can go out when hot too

 

[Bigmac]

Aftermarket carb?
Have you done a pressure vac test?
I am having trouble with my 036 pro, my factory zama wouldn’t tune, bought an eBay replacement zama, and it is way lean on the l screw, need 3-4 turns but can can tune it pretty well to, so it idles and piss revs well, will drop back down to an idle, response is good, if I piss rev it for five to ten seconds it wants to go lean at idle and race, like it has an air leak! But if I put the oem zama back on it acts totally different, I am not sure if I have bad carbs or other issues, mine pressure vac tests out great and has new fuel lines and the vent isn’t the issue. I am thinking it’s a bad carb, may try to mod the zama, but I don’t have much experience with doing that! Good luck!

 

[Simondo]

I would be opening the carb up to check for correct metering hight and diaphragm installation to eliminate....regardless of it being new. You say it repeats doing it and the saw fires up again even with this issue, so spark wouldn't ..Seem.. to be the first thing to check out unless its giving out after running for that short while. Carb first, coil second IMO

 

[drf256]

It’s either feeding to much fuel or not burning what you feed it.

Coil could be bad, but generally that’s all or none. It should misfire if it’s bad.

My bet is the carb. I’d change the spark plug first, why not, then try again.

Pressure test the carb and then open the metering side. Let’s see what’s up. If it’s am, anything is possible. If it’s a carb with the compensator horn, and you plugged it, it will hit the pump diaphragm and flood the saw out too.

 

[Al Smith]

If the spacer gasket is on the wrong side of the diaphragm it will flood sure as God made little green apples .I happen to know an old fart in Ohio who did that very same thing ,duh

 

[redlight066]

Been there. Intermittent spark. Your coil is dying a slow death. Very frustrating. Runs great, shuts off for no reason. As said above throw a fresh plug at it and check the kill switch wire for chaffing

 

[trooney]

Put a different coil on it and see. If its not that then either the carb as said before. I had that same thing on my 026 but the extra gas that would not burn off was due to making it rich compensating for a air leak.

 

[drf256]

ReRead your post.

Check flywheel key. Totally can do this, and takes less to shear a filed key.

Check carb anyway.

Unplug kill wire from coil, can choke to stop saw if thats the issue.

Swap in an oem coil. 024-046 should all work for testing.

Check continuity of kill switch wires. Check the connections at coil and switch.

Report back.

I've got an SEM AM coil here you can have for 036. I'll never use it.

 

[Scotty Overkill]

I wonder if there is corrosion somewhere in the spark plug wire causing a short.

New AM spark plug wire and coil.

 

[Scotty Overkill]

Coil or plug. I have had new plugs once hot expand enough to somehow short internally, must be a crack in the insulator. Try a known good plug, then try another coil. Bad coil can go out when hot too

I've literally had around 10 different plugs in this saw, even tried with different gaps and different heat plugs, so I've ruled that out....

 

[Scotty Overkill]

If it’s a carb with the compensator horn, and you plugged it, it will hit the pump diaphragm and flood the saw out too.

It's the non-horn carb (old style).. The OEM was a Tillotson, the one I used to replace it is a Chinese Zama..

I did tear it down and the metering and fuel diaphragms are correctly installed. Only thing I didn't do to the carb was remove the Welch plug.

 

[Scotty Overkill]

Been there. Intermittent spark. Your coil is dying a slow death. Very frustrating. Runs great, shuts off for no reason. As said above throw a fresh plug at it and check the kill switch wire for chaffing

Check continuity of kill switch wires. Check the connections at coil and switch.

Report back.

This is one of the only things I've overlooked, you guys brough it to light for me. I haven't replaced the kill wires, I'll give this a try this evening and see what happens. I'm hoping this does it. Lol

 

[Scotty Overkill]

I've got an SEM AM coil here you can have for 036. I'll never use

I appreciate that my friend, let me see if the coil wiring is bad. I can't imagine where it'd be bad, it wasnt rubbing anywhere, but who knows. I'll pull the coil wires off this evening and give it a try.

 

[Scotty Overkill]

Check flywheel key. Totally can do this, and takes less to shear a filed ke

This was the first thing I checked. I made a skinny key to advance the timing, that was my first guess......I installed a normal key back into it and it still had the issue.....

 

[trooney]

Even if its a new coil I would put another one on to see if it changes anything. Anything electronic is prone to failure from the get go.

 

[Chainsaw Jim]

I worked inventory for a wrecking yard and when it came to a vehicle that had been under water it wouldn't get anything electrical put on the list. Once submerged, wiring and electrical components have a shortened life.
Something else that comes to mind is the rings. Maybe they rusted and are now stuck.

 

[Scotty Overkill]

I worked inventory for a wrecking yard and when it came to a vehicle that had been under water it wouldn't get anything electrical put on the list. Once submerged, wiring and electrical components have a shortened life.
Something else that comes to mind is the rings. Maybe they rusted and are now stuck.

I tore it completely down, the rings are perfect. I went ahead and ported it while it was apart. Lol.

 

[Scotty Overkill]

Even if its a new coil I would put another one on to see if it changes anything. Anything electronic is prone to failure from the get go.

Well, I think I figured it out. Kinda stupid on my part, so here it is.

After coming home from work we had to finish up an ash tree removal. I just now got a chance to tear into the saw again. Removed the recoil and took the coil wire off and isolated it. Tried to start the saw, flooded.

So I was just about to throw the fuggin thing across the back yard, when I said to myself "check the flywheel gap again".

So I did. Low and behold, the north pole was gapped quite a bit more than the south pole at TDC. The south pole was dead nuts (business card), the north pole was near double and then some. This is an AM coil, and the top mounting hole is off. Rather than die grinder the top hole out, I put my old coil back on, set the gaps, put the recoil back on and she fired right up.

It had spark with the AM coil, must not have no been hot enough though. I have her ready to plow in some wood, but I'm pretty sure the neighbors wouldn't appreciate that at this hour....

So it'll have to wait til tomorrow....