Stihl 034 Chainsaw problems..

[frixmatthew]

I have a Stihl 034 chainsaw that won't idle, when you start it it revs really high like theres no needle in the carb controlling the gas flow.. i pulled it apart and it seemed like the needle was a little long cause the "float" or whatever that moves the needle had a little play in it, so i cleaned everything and checked so see if the needle was seating properly and it was so i put it back together and pulled it and it ran full throttle, i pulled the throttle a little and it bogged down.. I don't really know what to do from here, can someone help me figure out whats up with it.. Ill provide any information that you need if I can..

Also its not a Stihl 034 AV.. just a 034.

 

[Lawnranger]

The throttle control or carburetor linkage isn't stuck, is it? For a small two stroke engine to rev up high like that it would also need a lot of air to go along with all that fuel. If the engine was enriched at idle with enough fuel to run it at full speed without the excess air, it would most likely die due to the air/fuel ratio being so far to the rich side (not enough oxygen for the amount of fuel). If the engine had a large air leak such as a bad carburetor to engine mount gasket, it would be hard to start. The typical Stihl chainsaw has a four position master control switch and you have to depress the top throttle lock on the handle and pull the throttle to wide open the close the choke plate by moving that master control switch to the most downward position. This also sets the carburetor to a fast idle position. The starting procedure is as follows: set choke, and pull starter rope several times or until the engine "burps" (attempts to start) then move master control switch up one position to the fast idle position and continue pulling the starter rope until the engine starts. After the engine starts you are to "blip" the throttle which automatically moves the carburetor linkage back to a normal idle. If for some reason your throttle trigger or carburetor linkage is not working properly it could cause the condition you are describing. I'm sure you know how to start your chainsaw but I wrote out the instructions just in case I missed something.

You can always take your saw to the Stihl dealer and they will most likely take a look for free to see if anything is not functioning properly. Most dealers are willing to at least take a look and try to get you back in service asap so it's worth a try.

 

[frixmatthew]

The throttle control or carburetor linkage isn't stuck, is it? For a small two stroke engine to rev up high like that it would also need a lot of air to go along with all that fuel. If the engine was enriched at idle with enough fuel to run it at full speed without the excess air, it would most likely die due to the air/fuel ratio being so far to the rich side (not enough oxygen for the amount of fuel). If the engine had a large air leak such as a bad carburetor to engine mount gasket, it would be hard to start. The typical Stihl chainsaw has a four position master control switch and you have to depress the top throttle lock on the handle and pull the throttle to wide open the close the choke plate by moving that master control switch to the most downward position. This also sets the carburetor to a fast idle position. The starting procedure is as follows: set choke, and pull starter rope several times or until the engine "burps" (attempts to start) then move master control switch up one position to the fast idle position and continue pulling the starter rope until the engine starts. After the engine starts you are to "blip" the throttle which automatically moves the carburetor linkage back to a normal idle. If for some reason your throttle trigger or carburetor linkage is not working properly it could cause the condition you are describing. I'm sure you know how to start your chainsaw but I wrote out the instructions just in case I missed something.

You can always take your saw to the Stihl dealer and they will most likely take a look for free to see if anything is not functioning properly. Most dealers are willing to at least take a look and try to get you back in service asap so it's worth a try.

Well Like I said I pulled it apart looked at it, throttle isn't stuck it works perfectly. The chainsaw belong to my uncle that passed away in a wreck and he was a former mechanic and we were working on it one day and it wouldnt idle it would rev really high. I haven't tried adjusting the idle screws or anything, not sure if that would cause it, It'll rev high on choke and off choke I can pull the throttle while it revving high and it'll start bogging down but still revving pretty high.. I had the same problem with my Stihl weedeater I got from him, but that was a simple fix, but with the chainsaw Im clueless. I guess I could take it to a Stihl dealer and let them check it out, do you know if they charge for looking at it?

But thanks for the help Ill see what I can come up with and let you know..

 

[Lawnranger]

Somehow the engine is getting enough fuel and air to cause it to run that high. Remove the air cleaner box and look into the carburetor with the choke wide open to see if the throttle plate is closing all the way. The throttle trigger may work just fine but if the throttle plate shaft is binding it could cause the throttle plate to hang open. Did someone turn the idle speed screw too far in? Without seeing the saw it's difficult to pinpoint the problem so I'm giving you some more areas to check.

A friend of mine took his Sthil chainsaw to the local dealer after he disassembled the throttle trigger assembly and couldn't get the master control switch back in properly and the dealer fixed it right on the spot for him - no charge. My friend said it took two seconds to fix and I believe the Sthil dealer bought some customer loyalty with that. The dealer could have charged my friend but was smart enough not to.

 

[frixmatthew]

I pulled it apart again and checked and the throttle plate, its opening and closing just like it should. I decided to back the 2 screws on the carb out a little and started if with all the covers, it started fine but was revving high after a couple seconds it idled down a bit but not a whole lot, it was still revving a little high. I notice that the top plate on the carb with the 1 screw on it was sparyin out gas from around the gasket so I dont know if that would cause it, so Im going to go to a Stihl Dealer and get a gasket kit for the carb and replace all the gasket and see what it does.
Also theres no clutch on it due to one of the shoes breaking so Im not sure if that would cause,but I dont think it would.

But thanks for all the help you guys have given me, maybe I can get it running like it should be.

 

[bwestbrook]

Did you ever get saw fixed. I had one do that and it was the crankshaft seals allowing air to be sucked in and it would only run at full throttle. Changed them and it worked great. But I diagnosed this with a leakdown test.