Mercury engine idle - dying

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dlandersson
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Mercury engine idle - dying

Post by dlandersson »

For the first time since 2011, I find my Mercury 50HP engine - when at idle - dying to "off". This is unpleasant when I'm approaching the slip and I might need it again. :?

Any suggestions? Fuel additive? 8)

From another site:

PROBLEM: The engine stalls in neutral, at idle, only.
When your outboard starts right up, keeps running with throttle applied in neutral, but shuts down the moment you come back to idle speed in neutral, the issue is likely to be a sticky or broken AIS (automatic idle speed) valve. This valve controls idle speed by regulating air intake, and when it gets stuck in the wrong position, it can shut you down cold.

QUICK FIX: You need to clean or replace the valve; replacing is the favored option, because once the valve fails you, it always seems to get stuck again at some point down the road. This isn’t a tough job, but most folks will want their mechanic to tackle it. Meanwhile, you can save your trip by starting with the throttle slightly advanced in neutral, and bringing the throttle back as close to idle as possible without actually going into idle. In most cases, you’ll be turning about 700 RPM. Then shift into idle and then directly into forward, without any hesitation or pause. It may take a few tries, but when you do it fast enough, you can get the engine into forward while it’s still running. Once it’s in gear and running, your problems are over (throughout the RPM range). Just remember not to shift back into neutral, or the engine will cut out again. And obviously, shifting this fast can be hard on the engine; it’s okay to do it once or twice to save the day, but before taking the boat out again get that valve fixed.
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seahouse
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Re: Mercury engine idle - dying

Post by seahouse »

The AIS is one possibility.

How old is the fuel, do you use fuel stabilizer in it? If it's convenient, try fresh fuel and see if it improves, that's sometimes the easiest thing to try first.
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dlandersson
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Re: Mercury engine idle - dying

Post by dlandersson »

Yeah, that's a really good point, the fuel was mostly from last year with far too much "Sea Foam" in it - I don't use much fuel - mostly just to get in and out of the marina. But I don' need no engin' quittin' just when I'm making my slip approach. :|

I'm going to put in some fresh fuel (7 foot waves tomorrow, may as well do it then), a little "Sea Foam" and let it run for 30 minutes. 8)

seahouse wrote:The AIS is one possibility.

How old is the fuel, do you use fuel stabilizer in it? If it's convenient, try fresh fuel and see if it improves, that's sometimes the easiest thing to try first.
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kurz
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Re: Mercury engine idle - dying

Post by kurz »

is ist possible that this AIS is able to shut down the motor during normal use (gear in)?
My EFI 60hp all some hours turns off... But why????
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Sea Wind
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Re: Mercury engine idle - dying

Post by Sea Wind »

A few years ago, with my old 2-stroke I had a similar problem. It was solved with new sparkplugs. Are you getting the right number of RPMs in neutral?
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DaveB
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Re: Mercury engine idle - dying

Post by DaveB »

Using Reg. 10% ethonol will only last for 3 mo. if you use a additive maybe 6mo. Best to find reg. gas with no ethanol at your local marina and good for 1 year.
Even Sea Foam and others won't last compared to Reg. gas no/ethonal.
May cost you more per gal. but safer on your outboard, you seldom use it so try it.
Dave
PS: had same cutting out on my previous BF 50, changed the sensor and was fixed.


dlandersson wrote:Yeah, that's a really good point, the fuel was mostly from last year with far too much "Sea Foam" in it - I don't use much fuel - mostly just to get in and out of the marina. But I don' need no engin' quittin' just when I'm making my slip approach. :|

I'm going to put in some fresh fuel (7 foot waves tomorrow, may as well do it then), a little "Sea Foam" and let it run for 30 minutes. 8)

seahouse wrote:The AIS is one possibility.

How old is the fuel, do you use fuel stabilizer in it? If it's convenient, try fresh fuel and see if it improves, that's sometimes the easiest thing to try first.
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Re: Mercury engine idle - dying

Post by Ribbonslinger »

My 9.9 Mariner would run great but when I slowed down after a long run time it would stall. Replaced the gas, cleaned carb, new plugs, checked tank breather and checked fuel line to see if it was scavenging air but it still would die after a long run. Searched the problem on the internet. Lots of people had same problem with all types of motors. Most advised that mounting the primer bulb vertically would solve the problem. Tried it and it does not stall anymore. The steel ball in the bulb has to have gravity helping it out or it won,t work properly.
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Highlander
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Re: Mercury engine idle - dying

Post by Highlander »

I had a similar issue about 4 yrs ago & it was sticking rpm limiting switch telling the ecm the eng was over revving & would cut the rpm,s back to 1/4 throttle in gear & shut the eng. down as soon as u went into nuetral was an intermittent problem for 1 1/2yrs would not throw an eng, code until it finally completely failed :evil:

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Re: Mercury engine idle - dying

Post by powersailor »

My 60 hp EFI did the same thing because I didn't run it often enough. Added new fuel (it was low anyhow), added SeaFoam treatment to it and ran it on the water under power for about an hour just to be safe - problem has gone away. That would be a good thing to start with. My mechanic said it was the injectors clogging up from lack of use.
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dlandersson
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Re: Mercury engine idle - dying

Post by dlandersson »

That's my first plan of action. 8)
powersailor wrote:My 60 hp EFI did the same thing because I didn't run it often enough. Added new fuel (it was low anyhow), added SeaFoam treatment to it and ran it on the water under power for about an hour just to be safe - problem has gone away. That would be a good thing to start with. My mechanic said it was the injectors clogging up from lack of use.
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opie
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Re: Mercury engine idle - dying

Post by opie »

Try adjusting the idle screw up a tad to increase RPM's at idle. That fixed my similar problem.
raycarlson
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Re: Mercury engine idle - dying

Post by raycarlson »

waste of time guessing without knowing EFI or Carbs. only common shared problems would be small air leak in fuel tank primer bulb line or sparkplugs.
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