Very frustrated with my saw.

[Stihl 031AV]

Hello, I'm new to this forum. A while back my uncle gave me a Stihl 031AV and said it worked. I could never get her to start. I stopped working on it until now, because i take a class on small engines and was required to bring one in. Well, I've been working on it for a while and it wont get any fuel.

-Set the H and Low to their correct positions.
-It's got real good compression.
-Fuel Filter is clean
-Fuel Line is new
-Carburetor has been opened and is as clean as a whistle.
-I have spark. Its a brand new plug with correct gap.
-If i splash a little fuel directly into the cylinder it will start, but only for a few seconds.

Gas is getting through the carburetor, but not being pulled in. (Plug is not wet and it looks dry inside.)
I'm getting very frustrated because I don't know what else could be the problem.... Could it be vacuum? How do i check?
Thank you in advance for anyone who has ideas.

 

[WoodChuck'r]

Rep the n00b.

 

[Unit44]

Get a carb rebuild kit and install it, the ethanol has probably killed the diaphragm in the carb and it's not moving enough with the pulses to pull fuel. When you take it apart it may be pliable but probably nothing like a new one. This happened to me and a $16 carb kit cured it.... good luck!

 

[Dillio187]

give the impulse line a good look as well.

 

[jus2fat]

Pull the carb and get the model number off it...very important..!!
Make sure you get the right kit to match the model of your carb..!!

And as suggested...for sure...check the impulse line..!!

J2F

 

[Stihl 031AV]

Ok, thanks guys. I will get a carb rebuild kit. But after, if for some reason that doesn't work either, what would be the next step? Besides checking the impulse line for cracks/tears/etc? Thanks.

 

[jus2fat]

Check and replace the impulse line (if needed) first.

If that's your problem...??...maybe no need to do the carb kit..??
Ya probably will need to...but I have been surprised before..!!

If you have good compression and good spark...all ya need is fuel..!!
That's just to get it started..
I'll assume in your class you've learned how to adjust a carb.

J2F

 

[Stihl 031AV]

Yea i can adjust the carb. Alright thank you.

 

[brownbuttlover]

theres a couple screens in a carb,one is under a plug have to remove it to see it, may just buy a new carb

 

[Snyper438]

Be sure to check the rebuild guide for your carb. (most manufactures have guides available online) Make sure all gaskets and diaphrams are in the correct order. Pay close attention to the metering lever, if it's set too low you'll never get fuel. From there, given all fuel lines are good, i'd be suspecting a possible air leak keeping fuel too lean. Good luck.

Ed.

 

[Adirondackstihl]

I bet the metering diaphragm as are both diaphragms are stiffer than a wedding night woody. As mentioned before, put a carb rebuild kit in her....don't just opt for the diaphragm kit either...go full out and put a new needle and such in her. Carb rebuild kits run around $15-$20.

 

[Stihl 031AV]

hahaha alright. lol um once i find out the exact carburetor tomorrow, do you know of a good site i could order one? I'm pretty sure its a tillotson but not sure which model. I guess i could just Google it, but i mean is there a website that you would go to yourself?

 

[jdemaris]

Could it be vacuum? How do i check?
Thank you in advance for anyone who has ideas.

If you're confident the carb is OK and the fuel pump in it is hooked up to good vacuum - I'd suspect a big vacuum a leak. If I had the saw here, I'd just pressure check it. But that's hard to too unless you've got the 031 block-off kit (I do).

In most cases, a vacuum leak big enough to cause a "no start" is going to be the crankshaft seal on the sprocket side. It's easier just to pull the sprocket and look at it, rather then try to pressure (or vacuum) test the crankcase.

I don't want to insult your intelligence or skill - but did you check the little fuel filter inside the carb? That is a common problem area, especially in homeowner saws that don't get the chains sharpened properly. Dull chains make dust instead of chips and that dust gets past the tank filter and plugs the little carb filter. I've had to unplug many over years. Very easy to get to on an 030 or 031.

 

[Stihl 031AV]

haha not insulted all ideas are welcome at this point. Haha Im pretty sure that the filter was clear when I had it apart a week or two ago. But just for the heck of it i'll look again tomarrow morning. Thanks.

 

[vhmtach38]

Snyper438
Be sure to check the rebuild guide for your carb. (most manufactures have guides available online) Make sure all gaskets and diaphrams are in the correct order. Pay close attention to the metering lever, if it's set too low you'll never get fuel. From there, given all fuel lines are good, i'd be suspecting a possible air leak keeping fuel too lean. Good luck.


Yes pay attention to the metering lever if its set too low ...little or no fuel...too high and it will flood and spit fuel out the carb...those metering levers on the 031av are very sensitive to their position.....good luck....:msp_smile:

 

[Eric Modell]

If you are not getting fuel to the engine You can prime the engine through the air intake. I use a squirt bottle with gas oil mix. The bottle I use is similar to a mustard bottle. a small squirt will let the saw fire,

If the saw has bean sitting for a while this might get it started and let you move forward.

 

[Stihl 031AV]

Ok, I want to try and check the vacuum before I mess with the carb more. Is it possible to like put my finger over the impulse line and have somone to pull to see if I have suction or something like that? (I dont know much about the vacuum stuff.) and I dont have a pressure tester...

 

[Stihl 031AV]

Thats a good idea too, Eric. Thanks.

 

[SawTroll]

How can you be frustrated by a saw that old - afterall this isn't about the much superior Jonsereds of the early 1970s......

 

[sugarbush]

Ok, I want to try and check the vacuum before I mess with the carb more. Is it possible to like put my finger over the impulse line and have somone to pull to see if I have suction or something like that? (I dont know much about the vacuum stuff.) and I dont have a pressure tester...

remove the carb and put a little grease over the impulse hose, pull over and should suck in.