Hard restart

[Dale Hatfield]

OK here  is the deal. We run a pretty big fleet of husky saws and a small run of others. Starting early this spring when we got the first hot spell. WE were having  a hot restart problem with certain model . Then a student  bought a new  Stihl saw in and we have same trouble with it.  As well as I had same problem over the weekend with a couple of my carving saws. It seams to be newer saws that are having the trouble. I have some older dogs that seam to be ok .
Now I know how to adjust carb. Saws really are running just fine, They sound the same as they always have. No increase in rpm, No lack of power in the cut. Not running  rich or lean.
See i thought this was just this model of saw but now problem is spreading to home saws and others around.
I have to think that its the fuel. I know whats in mine  Mid grade Marathon with Saber mixed at 50 to 1.  Work mix is 50 to 1 as well but i dont know what grade of gas but its Stihl mix oil. The gas station and the school both get their fuel from same delivery company.
I wounder what has changed in the fuel.  I will get with fuel company on Tuesday. The tank we have at school gets filled once a week,and id guess that about the same at filling station where i buy mine.  So I know the gas is pretty fresh unless its aged before delivery.

[jokers]

I wonder if your recent gas has more ethanol or something else that is causing vapor lock. Maybe you`ve been burning off the winter reserves of oxygenated fuel?

[joe_indi]

I  think the possible  reason, as Jokers pointed out, is a vapor lock.
To confirm this, open the fuel cap of the saw to remove any negative pressure and close it.
With the choke in the on position, crank the engine over slowly once or twice.This will help remove any air in the pumping and metering chambers of the carburator.
Try to start the saw now.
If the cause was  really a vapor lock, your saw should start easily.

Another possibility is that there is something wrong with the  fuel mix that is creating a partial blockage in the fuel pickup body.Possibly the oil.Gummy oil tends to do this.
A partially blocked pickup body could cause a vapor lock since the pump will create more vacuum in the fuel hose.The fuel then tends to release air into the fuel hose. Replace the pickup body of a saw and see if it runs differently, at least for some time, that is, till the pickup body gets blocked again.

[jbeat]

I agree, probably a vapor lock / fuel supply problem. I've actually seen gas boil in the tank during heavy useage in hot weather. Or, it may be saw gremlins telling you to go home and "fire up the skillmill".

[Dale Hatfield]

Update
The  answer I got from fuel deliver company was  winter /summer blend should be the only differance.
Its not a boil problem. Its like a heat sink problem. You can fill up cold and run the saw just fine. For One tank. then go to refuel and its all over. In the amount of time it takes for refuel, It has caught a case of i dont wont to run. PUll your guts out or wait it out is the only answer.
Dale

[olyman]

dale--if thats the case--id take the blow gun--and blow thru the recoil housing--as chips from sawing get in there---and start to plug fins and around the cooling area of the tank--had this happen over a period of a month with the 264 oly--and there was almost nothing on the recoil hsg--took it off--o my!!!!  blew everything out and clean--end of the same problem your having---

[karl]

I have, or rather HAD a new Husky 455 Rancher that won't start after the first run without further priming and choking and swearing.
Took it back twice to the dealer, they "ran a couple tanks of gas through it and found no problem- that I needed to learn to start it" Second time they decided it "Was the new epa compliant carb, they require more priming"

My solution was to give the saw to my son and continue using my old 55 that starts on the first pull when warm.

[thecfarm]

I think Dale is having a VERY hard time starting his.Like 10-20 pulls?On my 372 Husky,I set that down warm for 15-20 minutes,I have to use the choke.Takes 2-3 pulls to start.Something about the way the saw is set up to remove all the gas out of the carb?

[RaisedByWolves]

Heres what I would do.



Run the saw untill you anticipate that you will have the problem. Have the problem crop up and check the plug to see if its wet or not. This will tell you if its starving for furl or if it is flooding.

When the saw is hot and you let it sit or refill it with nice cool fuel the heat can soak into the tank, expand the fuel and flood the saw.


Since you may not have been expecting this, you will be choking a flooded saw in this scenerio when you should be trying to start at WOT.


If my saws dont fire in the first few pulls I generally hold the throttle open while pulling it. If that dont work I go for the choke, this method prevents me from flooding it out and fouling the plug.

[ehp]

Ok here is what I think is happening , first your older saws had a squish of .050 so lots of room to keep the motor running cool plus a non etech type of muffler saws today are running a squish of .030 so alot tighter to burn hotter plus cleaner , well thats what the factory thinks anyways . Now with the engine having a tighter squish it produces alot more heat in the motor plus the new cat mufflers run alot hotter to boot as well, so with this problem once you get the motor real hot and shut it off the heat raises in the saw to the point where it doesnot want to start , if you pull it a couple times and it willnot start put the choke on and pull it once, take  choke back off and you will have to pull it a 4 to 5 times to get it to fire with the fast idle on . How to fix the problem. open up the muffler to let the heat out of the motor . it will run alot better