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Chainsaw will start when primed, but not run

S

sam dupont

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Jonsered 910. Ran last year, not now. Cleaned the carb, but still won't run. Pour fuel down its throat and it starts and idles fine, for 2 seconds. 10 drops of fuel down the spark plug hole and it pops right off; idles. So I know it's fuel related. Fuel line clear, pulse hose good. S199 Carb.
 
Last edited:
Runs a short time

- getting spark
- Getting air
- fuel only what you dump in

So . . .
- fuel line cracked, broken or clogged
- you cleaned carb, did you assure venturi hole is not clogged ?

That's my best guesses
 
Nice old saw, Johnsred are the best.
Primer bulb is pulling fuel fine?
I'd check the pickup, had a chunk of plastic from an old cap fall off once in the tank and plug the pickup.
 
I have mostly Stihl stuff and an older Echo line trimmer, but when they start acting up I have had pretty good luck using seafoam mixed in the fuel. The fuel sucks these days and plays havoc with the little venturis and gaskets. All of the other suggestions are good places to start too.
 
This stuff works awesome too, I was skeptical, but its really good. Stabil rep hooked up a few years ago.
upload_2021-6-15_11-14-0.png
 
Dealer installed new carb on my Stihl last fall. Said the ethanol ruined carb. Now I run fuel in the 1 qt. cans. No problems so far. A plus is that it smells like race fuel. :lol:
 
UPDATE
93 octane, no alcohol
Carb cleaner passes through every orifice, using the little red tube. Blew out with air afterwards.
No primer bulb, blew through supply line successfully.

Looking like the diaphrams, though they didn't show any cracks holding them to the Sun.
 
Didn't most replies my $.02 clogged jet, small strand of wire works well.
 
Moms68 said:
I have mostly Stihl stuff and an older Echo line trimmer, but when they start acting up I have had pretty good luck using seafoam mixed in the fuel. The fuel sucks these days and plays havoc with the little venturis and gaskets. All of the other suggestions are good places to start too.
Click to expand...

I've found a gas station that sells non ethanol gas - it's a bit more but very cheap "insurance" for small engines as it never does what the ethanol stuff does - clogging up the carbs . . .

Try and find one that sells it - it's the only gas I use for small engines, chainsaws, tillers, lawn mowers
 
If you need a small amount of alcohol free gas premix at home depot.
 
super-bee_ski said:
See if there is a Diaphram in carb, sometimes they develop a leak
Click to expand...

Sometimes on those the gas cap has a check valve... can pull a vacuum on the tank real fast and let no gas in.... id try it with a loose cap and see if any difference to test.
 
Double check the line in the tank. You are sucking air.
 
sam dupont said:
Jonsered 910. Ran last year, not now. Cleaned the carb, but still won't run. Pour fuel down its throat and it starts and idles fine, for 2 seconds. 10 drops of fuel down the spark plug hole and it pops right off; idles. So I know it's fuel related. Fuel line clear, pulse hose good. S199 Carb.
Click to expand...
I had a two stroke engine with similar symptoms, the spark arrestor on the muffler was blocked with carbon and cleaning it fixed the problem.
 
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