Stihl 031 AV Starts and dies after 5 seconds

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Ronald Montenieri

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Joined
Feb 6, 2019
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Location
CT
Hi Guys, I have a Stihl 031 AV chain saw that suddenly won't stay running. I put a new tank of freshly mixed gas (40:1), a new plug and cleaned the air filter, which really didn't need it. I thought it was the carb so I pulled it off and cleaned it and blew it out with compressed air. It looked perfect. Same thing.... starts and runs for a few seconds and shuts off. I took the carb apart again... no improvement. I pulled the muffler and checked for blockages... none. It is so old so there is no spark arrestor but the muffler was clean. The piston and rings look great and show no scoring or buildup of carbon. I also put in a new fuel line and filter.

Thoroughly frustrated, I did something I rarely do, I took it to 2 repair shops in mid-CT and was told by both to take it home and bury it because parts were no longer available. I know it is 40+ years old but it still looks almost new and ran like a race car until it quit. I ordered a new Walbro carb to replace the Tillitson carb... same thing, starts and dies. I started it without the gas cap too thinking it might be the vent. Still dies. It starts up immediately on starting fluid and runs fiercely for the 5 seconds, but still dies just like it does when the throttle is locked wide open and the choke is on, although it sounds like it wants to stay running longer when choked.

I SWEAR it's a fuel delivery problem but I don't know what to try next.......?????

This thing ran like a bear and doesn't even look its age. I bought it brand new and cared for it like a baby. Any suggestions before I buy a new suit for its burial would be greatly welcomed. Thanks, Ron
 
Fixed an old 031av the other day for a friend and said he cleaned the carb out but he missed the screen and it was plugged solid with the fine stuff. Cut up a down oak with it - Runs like a champ now? Very Good saw!
 
Took HarleyT's advise and went for the points but never got the flywheel off. When I split the fuel tank housing to expose the flywheel I saw a large tear in the fuel filter line at the top of the fuel tank. Don't know how I missed it before. I can order that molded fuel line with no problem but I can't find a fuel tank gasket anywhere. Can anyone guide me to one?

Also, that fuel line is also the grommet at the top of the tank and a white plastic thing pushes into it. Is that white plastic thing just a fancy 90 degree elbow or is it a valve of some kind? Thanks, Ron
 
There should be two access plugs on the flywheel that are easily removed by just loosening the screws a little and wiggle them out.
Then the points can be cleaned and adjusted.
 
My bad. This is the first time I have taken that side of the saw apart this far, but as it turns out it was a blessing also because I never would have seen the tear in the fuel line way up by the grommet if I didn't. I suppose there's no harm done as long as I can get a new gasket. Thanks very much, Ron
 
I was able to order 2 fuel tank gaskets (because I know me), the elbo connector, and 2 fuel lines for around $20.00. The parts won't be here for almost a week which gives me time to clean all the gook from that side of the saw with spray cleaner and compressed air, and then take a peek at the points. Whether it runs or not when I'm done I want to thank you for all of your help because I never would have gotten this far without your help and encouragement. I don't want to jinx this, but I have a good feeling about this. thanks, Ron
P.S. You da man
 
Good luck Ron, keep everyone posted. the 031 is a legend of a Saw - in that it's both a strong performer (I know only by reputation) and can be a real PITA to get running right (I know by experience).
 
Mine was starting and stopping after 5 seconds also .Mighty vac found clutch side crank seal was leaking bad .Love this saw .
 

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