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I have an older CS400 chain saw and it has been a dream. This morning I got it out and it will start and idle, but when I pull the trigger, it dies. I very recently changed the spark plug, air filter, fuel filter and has new gas. Any thoughts
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(06-02-2018, 03:49 PM)wannabedivin Wrote: I have an older CS400 chain saw and it has been a dream. This morning I got it out and it will start and idle, but when I pull the trigger, it dies. I very recently changed the spark plug, air filter, fuel filter and has new gas. Any thoughts
Is the chain brake engaged?
John
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(06-02-2018, 05:39 PM)jteneyck Wrote: Is the chain brake engaged?
John
Brake not engaged, it just dies like it is out of gas when I pull the triggers. starts and idles fine
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Spark arrester clogged ? Roly
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Adjust the carb. It is best done with a tachometer, but can get "close enough" without.
Let it idle for a while so it warms up. This doesn't work well unless the engine is warmed up.
Disengage the chain break.
Turn the "I" so it idles faster just until the chain starts to turn on its own. Then back it off about 1/4 turn.
Then, open the "L" a little bit. Most often when the saw dies at rev up, this is set too lean. If it idles fine, back that out until it doesn't sound so good...then slowly turn it back in until it sounds good again.
Try squeezing the trigger now. If that stalls it, start it again, and see if you can get it up to speed by slowly squeezing the trigger.
If you can't get it to go after trying that a few times, you may well need a new carb. Ethanol is heck on small engines - especially carb seals. Replace the carb and see if you can find ethanol free fuel to run in it. Use high quality 2 cycle oil. Echo Red Armor is one of the best. Better than Husqvarna and Stihl as I understand it - but either of those will do just fine. I use Amsoil Sabre at 50:1.
If you get it up to speed, hold it wide open (or, better, have somebody else hold it wide open so you can make adjustments while they keep 2 hands on the saw in case it kicks back). Turn the "H" screw in until it "4-cycles" or skips strokes. Then back it out a little. Repeat the "I" and the "L" screws again.
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Will it rev if you ease the choke out a bit? If it does, it's starving for gas in some way.
Steve
Mo.
I miss the days of using my dinghy with a girlfriend too. Zack Butler-4/18/24
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WaterlooMark 02/9/2020
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(06-02-2018, 08:33 PM)Stwood_ Wrote: Will it rev if you ease the choke out a bit? If it does, it's starving for gas in some way.
Backing out the "L" screw gives it a richer mix at acceleration...
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(06-02-2018, 03:49 PM)wannabedivin Wrote: I have an older CS400 chain saw and it has been a dream. This morning I got it out and it will start and idle, but when I pull the trigger, it dies. I very recently changed the spark plug, air filter, fuel filter and has new gas. Any thoughts
Another possibility is the fuel pump diaphragm. They get hard from the new gas and won't pump enough gas. Could also be gummed up fuel or dirt in carb. Roly
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(06-03-2018, 07:43 AM)Roly Wrote: Another possibility is the fuel pump diaphragm. They get hard from the new gas and won't pump enough gas. Could also be gummed up fuel or dirt in carb. Roly
Could also be fuel lines that are going soft from the ethanol gas. Or a clogged fuel tank vent. There are a lot of possibilities. Start with the simple ones and work your way up.
John
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Some things I've learned about small engines.
Do a methodical search of the saw's systems before changing any adjustments. If it hasn't been adjusted recently, the problem probably is not an adjustment issue. IMHO, Adjusting a simple 2-strolk to get it running is not fixing the problem.
Is the carb getting air? Wrapper still on the new air filter?
Will it run with the fuel cap off/loose? Vacuum locked?
Does the chain slide freely?
Are you sure the gas is fresh and not that old stuff from the back of the shed?
Is the fuel filter clogged? New
Is the choke working properly?
Did the fuel delivery hose kink when you put in the new fuel filter?
Is the fuel filter in backwards?
You already know it's getting spark but possibly too weak? Is it gapped right?
