Happened again, no idle...

[CaseyForrest]

Well, after 3/4 gallon of fuel milling some siding, it started acting up again. Wont hold an idle, it'll re-start every time, but only if I lock the throttle half/full open. It doesnt seem like the coil as it slowly dies out rather than just quit. It runs fine wide open, a little rich in mid throttle, and anything less it starts to stumble and hesitate.

Any help is greatly appreciated.

 

[Lakeside53]

Sounds like it's flooding... Pressure test the carb...

Where is your L needle set (turns). I've seen where there is a seal problem and the carb had to be set way too rich to compensate for the leak to idle, then every now and then the seal "seals" and now it coughs out due to too rich a mixture. Did you pressure test the saw after assembly?

 

[CaseyForrest]

No, I did not pressure test after the rebuild. I know I should have, but everything seems to be allright except idle.

How does one pressure test the carb? Id have to go out and mess with the needle to count, Im not completely sure. It didnt smoke while I put that 3/4 gallon throught it, and it would sit and idle for a couple minutes after a cut while I was stacking and stickering the wood. And then boom, idle problems with no messing with carb adjustments.

 

[havvey]

test

use a crankcase leak tester a bulb type put it on the fuel barb and pump up to say 4 lbs or bars. if it falls right back to 0 or refuses to pump up you have a problem. (i would not get real worried) if it fell real slow and i mean real slow.

 

[Lakeside53]

No, I did not pressure test after the rebuild. I know I should have, but everything seems to be allright except idle.

How does one pressure test the carb? Id have to go out and mess with the needle to count, Im not completely sure. It didnt smoke while I put that 3/4 gallon throught it, and it would sit and idle for a couple minutes after a cut while I was stacking and stickering the wood. And then boom, idle problems with no messing with carb adjustments.

So.... you can still a have a leak though.... and idle is where it will show up...


Carb test is as harvey says, but I usually pump them up to .8 bar.

 

[CaseyForrest]

Ok, So tell me what happens if I do find a leak. And if I dont find a leak.

 

[HiOctane]

Ok, So tell me what happens if I do find a leak. And if I dont find a leak.

If its leaking or losing pressure,its probably by the inlet lever tip.If not leaking,then look for inlet lever level.

 

[Lakeside53]

It can also be gaskets.. If it leaks, put the entire carb in some fluid and watch where the bubbles come from. If nothing is found with the carb, to eliminate a bunch of variables, you really have to do a pressure AND vacuum test of the engine assembly..

 

[GASoline71]

How old was the fuel you used?

Gary

 

[CaseyForrest]

How old was the fuel you used?

Gary

fuel was about an hour old.

 

[CaseyForrest]

ok, i know i can get a vac pump, but where do i get a pressure pump for these tests?

 

[GASoline71]

fuel was about an hour old.

Cool... jus' tryin' to cover all the bases.

Gary

 

[thompson1600]

My first pressure tester was an old manual blood pressure gauge. Just cut the tube off at the cuff. Worked great. Just had to go online to find a conversion for the units of measurement with the BP gauge vs what is given. For stihl it's usually listed as BARS.

Tom

 

[Lakeside53]

ok, i know i can get a vac pump, but where do i get a pressure pump for these tests?

Even a tire pump works fine...

 

[CaseyForrest]

Did I find my problem?

You can see where the intake boot comes through its split at the bolts, all the way back to the metal ring. The carb checks out otherwise.

 

[Lakeside53]

Looks like it to me... Needs replacing anyhow, but something doesn't look right about that boot. Find the part numbrr on it (it is there... tiny, but cast as part of the rubber) and compare it to the replacement part.

 

[CaseyForrest]

Called my shop and ordered the manifold, impulse tube and a carb kit, all in stock. Hopefully Ill have it going again this weekend.

Thanks for your help Lake.

 

[West Texas]

I like bold decisions; otherwise you could nickle and dime that thing to death with tests and parts.

 

[CaseyForrest]

I am notorious for nickel and diming chit too. I look at it as an investment, or it needed replacing anyway!!