Saw Won't Run

[Bills Oak]

I recently was asked to work on a saw for an old friend & I agreed. It is an older large all metal sears saw--I'm guessing about 10-15 years old, sat a long time. Equivalent to a Poulan 3400, 3700, good older saw, ported piston model. I checked the compression--ok-cylinder & piston look good. I flushed the fuel system installed new fuel line & filter, rebuilt carb. Saw cranked up, smoked a little but finally settled down, adjusted carb to idle fine, lots of power & speed. Used saw to make a few cuts, shut down saw & it has not started since, great spark but does not seem to want to draw fuel out of the carb! I work on a lot of older McCulloch saws & have seen the block seals go bad but not this fast. I am stumped on this one!--Any help is appreciated--Thanks, Bill Irvine

 

[sedanman]

WHere does the carb get its impulse signal from? I had a little string trimmer that pi$$ed me off so bad I almost smashed it. It would run on carb cleaner and the carb would make another machine run, but wouldnt draw fuel n this machine. The impulse port in the jug was plugged with carbon. I de-carbonized the port and the trimmer ran fine.

 

[cbfarmall]

Can't help with troubleshooting from my computer, but I have one of those Sears saw like the Poulan 3700. Bought new on Aug 25, 1987 for $315. Original owner wrote that on the manual cover. Not a bad saw, though it doesn't compare to my Stihls. It has cut alot of wood in its day, including a few large oak stumps.

It's piston ported to be sure, but it has the unfortunate aluminum bore/chrome piston design.

Only troubleshooting I can offer, is if it runs when you squirt gas down the throat. Didn't notice if you ran that test. I don't suppose the flywheel key sheared?

Sedan, pretty sure that saw gets impulse through a port, not a hose.

Chris B.

 

[Mange]

Yes, I would proberbly look at the impulse port befor rebuild carb.
I have seen this many newer saws 1970-80-90.

 

[sedanman]

Chris, The trimmer in my example got its impulse though a port not a hose too. To check for a restricted impulse port, take the carb off and put a small dab of light grease over the port. Pullling the engine over should produce enough pulse to dislodge the grease.

 

[cbfarmall]

Sedan,

I wasn't arguing with you. You just posed a question and I answered. Maybe I misread your reply. Wouldn't be the first time.

I'll remember your diagnosis method for impulse. On my 042, I could feel the impulse with my finger when I cranked it over with the starter.

Chris B.

 

[sedanman]

Chris, Don't take my reply as an arguement, I was merely trying to make my piont more clear.

 

[Bills Oak]

Well it's running!----I checked the impulse port & it was clear, I also replaced the carb to block gasket in case it was leaking. Still would not start so I took out the spark plug & shot some Rust Blaster into the engine as a last ditch effort, put the plug back pulled it about 30 times & it came to life --smoked like crazy for a minute or so then I adjusted the idle jet & the high speed jet & it runs like new--GO FIGURE!--I guess it was carboned or clogged up some where. I let her cool off for a few hours & she cranked right up & runs great--Thanks for all of the suggestions---I'm finally over this one!--BILL IRVINE