115 hp Merc stalls when shifting

petemoe

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Apr 24, 2004
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I have a 1980 Merc 115 IL 6 that stalls going from high idle back to neutral, and shifting back into gear. Runs very good otherwise. Any ideas?<br /><br /> Pierre
 

phatmanmike

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Oct 24, 2003
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Re: 115 hp Merc stalls when shifting

sounds like your carbs are dirty... have they ever been rebuilt... typically that is the problem when your idle jets/ idel circuit , also known as low speed jets, get dirty....<br /><br />i had similar problem with my suzuki 65 then it blew up
 

petemoe

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Apr 24, 2004
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Re: 115 hp Merc stalls when shifting

Originally posted by phatmanmike:<br />sounds like your carbs are dirty... have they ever been rebuilt... typically that is the problem when your idle jets/ idel circuit , also known as low speed jets, get dirty....<br /><br />i had similar problem with my suzuki 65 then it blew up
Thanks for the reply, I'll tear down the carbs and rebuild them.
 

emckelvy

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Jan 16, 2004
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Re: 115 hp Merc stalls when shifting

Before you tear apart the carbs, just take each idle mixture adjusting screw and turn it approx 1/8 to 1/4 turns CCW (rich). It may just be a case of slightly lean idle mixture, which the Big Sixes don't like.<br /><br />This may make your idle a tad 'lumpy', but it should make the motor less prone to lean-stalling.<br /><br />If you really want to get it tweaked in, with a warmed-up motor and idling in gear in the water, adjust each needle. Find the range by very slowly moving CW until it leans out and begins to slow down. Then, back out CCW (rich) until it begins to slow again. Leave each needle adjusted about 1/8 or so turns to the rich side of the midpoint of the lean-rich range that you find while tweaking the mixture needle back and forth.<br /><br />What this'll do is optimize the adjustment on each carb, and overall you'll have a smoother idle and more consistent takeoff.<br /><br />If you find that you bog down upon acceleration, take each needle 1/8 turn CCW (rich) and then see if it improves.<br /><br />This, of course, assumes no other problems such as dirty/incorrect spark plugs, dirty distributor cap (inside), low compression, etc.<br /><br />Note that a dose of Deep Creep spray in the carbs and Seafoam in the fuel will likely improve running, too.<br /><br />Check out the particulars at www.seafoamsales.com<br /><br />HTH.......ed
 

ZmOz

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Aug 13, 2003
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Re: 115 hp Merc stalls when shifting

Originally posted by Ed Mc.:<br /><br />Note that a dose of Deep Creep spray in the carbs and Seafoam in the fuel will likely improve running, too.<br /><br />Check out the particulars at www.seafoamsales.com<br /><br />HTH.......ed
I had the exact same problem in my 150hp inline 6. Sprayed a can of deep creep through the carbs, problem went away. :)
 

petemoe

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Apr 24, 2004
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Re: 115 hp Merc stalls when shifting

Thank you to everyone for your advice. You guys are a huge help. Happy boating.<br /><br /> Pierre
 
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