Just bad gas?

[gemniii]

So I searched, did not find a pertinent thread.
Anyways -
My 660's had been sitting empty for a while. Both had been getting a little use last winter. Bought a new gallon of HO gas, made the 40:1 mix and 660a fired up. Sthil FS45? weedwacker fired up on same mix.
Short break for travel, 3 weeks later, bought a new gallon of HO gas, made another 40:1 mix (Bailey's synthetic oil) tried 660b. Darn near pulled my arm off, no fire. Tried the same mix on 660a - no fire and weedwacker, no fire at all.
Gas was bought at my local station I've been getting saw gas from it for years, but I suspect that I HAD been lucky before.

Bought new plugs and a $8 quart of 1:50 fuel at the local Stihl dealer. Using that and an appropriate shot of SeaFoam 660a runs well, 660b fires and dies. Both had run like a raped ape at freezing temps last winter, now it's 90 degrees F and 100% humidity. Both saws pump fuel, 660B compression is 145. Both at 1 turn out for low and high.

So - three questions -
How long should it take to get the carb "self cleaned" on 660b?

Do I need one of you to walk me thru a carb rebuild?

Has anyone else experienced this due to bad gas?
thanks in advance

 

[GASoline71]

The station could have got a bad batch, or there was water in their tanks.

Try a different station... see if it makes a difference.

Gary

 

[CTYank]

Can we assume that you dumped the suspect fuel out of the tanks before filling with the new mix?

Fuel probs can even be related to weather. Years back, my dad's car ran extremely lousy after filling up at a nearby station. Turns out, their access to fill their tanks was leaky and down-slope from a good section of their lot. What he got was about 1/3 water. Water in gasoline tanks is an ongoing challenge.

Once you get an engine running, it'll continually purge its carb with the fuel in the tank. As a last resort, a couple of drops of mix down the carb throat should help getting it to fire up. Small amounts of spray carb cleaner work too. For fire-safety, put filter back in place before cranking. Mix is better for lubing things, obviously.

 

[gemniii]

Oh yes, dumped the fuel out of all of them, gave them about 30 cranks with the plug out to try and get the fuel in the lines out.

 

[gemniii]

Update - score another for Seafoam


After doing a routine of going down and about every other day and pulling the 660b it started to fire a bit. Three days ago I put in carefully measured 2 glugs of Seafoam, it would still fire briefly and die. Same yesterday. Today fired and ran.

Note to self - "tune" saws weekly to keep them running. Don't get any more saws.

unless I get a good deal on an 880 size machine

 

[gemniii]

One more update.

All are up and running well. Seafoam to the rescue. Now I just need an inexpensive double ended 7' bar.

 

[galde]

fuel issues

Sometimes fuel problems can be due to wrong-season fuel. Winter formulated fuel has higher vapor pressure than summer fuel. If fuel is suspect ( I never trust fuel in equipment that I buy used or take in to work on ), I pour it into a transparent container and let it sit overnight. I then hold it up to the light and inspect for a gunky layer at the bottom. You might be surprised at what you find. Any fuel that I haven't mixed myself gets mixed with used oil and goes into my can for burning brush piles.

 

[fatboymoe]

This is the very reason I am now using Tru-Fuel @ 40-1 for all my saws. I know it's not cost effective for the everyday user, but for the casual user like myself it's been great insurance against the above stated fuel problems. I still use my own pre-mix for my lawn equipment that gets used weekly. I mix 2.5 gallons of mix and after 30 days, what's left goes into my truck. California gas just plain sucks!