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2010 50 hp Mercury slow to idle down

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Dodgeman

New member
I just purchased this engine, it has 3 carbs on it, I was told it hasn't been ran much in the last two years.

My boat has 20 year old remote controls, I think I have the shifter and throttle cables in the correct positions.

We took the boat out this past weekend for the first time. I did crank it on muffs when I put the engine on my boat. It was a little hard to start and when we idled it down really slow it would idle a little while then die. After running wide open or half wide open, when we would slow down and go to neutral it would take it several seconds to idle back down.

The boat started out running about 32 mph and after we ran it a while it ran 35 when we headed back to the ramp.

Any ideas would be appreciated.

Thank
 
Sounds like the carb idle screws need adjustment. You might want to ask someone knowledgeable for help --an old guy (like me) who's messed with carbs for decades.

Jeff
 
Just tuned a 115 Mariner. The idle jets were out a mile. When I set them right it idled way too high. Had to readjust the throttle cable a few times to get here to idle down.

Sound familiar?

Jeff
 
When mine idles down it's fine, but when you put it in gear and go up with the throttle a ways or even wide open it doesn't idle back down when you go to neutral, it takes it a few seconds to idle down all the way.

Is there a starting point on the three idle screws, from all the way in?
 
It rained all weekend and didn't get to put the boat in the water but did look over the linkage and adjusted it a little. When you went to neutral the arm for the timing and idle wouldn't go all the way to the stop, we adjusted it and it's a lot better.
 
Goodman! Be sure to re-adjust those idle mixture screws when (or if!) the weather breaks.

As the song goes, "Rainy days and Mondays get me down!" We had BOTH today!

Jeff
 
Can you give me a heads up on how to adjust the idle screws, is there a starting point, so far out from all the way in, does one need to be more than the others?
 
1. Warm up motor with boat on the trailer or tied to a dock (so it can't move and trick you).

2. Put it in gear. If it won't stay idling in gear, add enough throttle until it does (but the least it needs to stay running).

3. Take one idle mixture adjustment at a time and SLOWLY turn it IN until the motor either stalls or--hopefully--picks up rpms.

4. If it stalls, add a full turn OUT (CCW) and get her running again. Boot it good in neutral to 'clean the plugs'.

5. If the motor picked up as you turned the screw inward, keep going until the motor starts to slow down, then quickly add a turn OUT. Go to the other carb and repeat, then go to the first one and repeat again. Take your time and let the motor 'smooth out' as you slowly turn the screws a bit at a time.

6. When you have the smoothest idle, add 1/4 turn OUT on both idle screws, then see if the motor picks up nicely as you add throttle. (Good time to take her for a ride.) If not, add another 1/4 turn OUT.

Jeff

PS: Make sure you have lots of fresh gas in the tank and the vent is OPEN.
 
Great information Jeff, I will do this. This engine has three carbs on it so I assume the procedure is the same.

I'm sure everyone here appreciates the people that take the time to help people, that's what it's all about right?
 
Jeff one last question, we use this boat to troll and we need it to idle in gear as slow as it will go, any tricks to get it to idle slowly?
 
Proper carb idle adjustment, but the smart move is to use a small "kicker" outboard instead, something like 3 to 5 hp.

Jeff
 
Thanks Jeff, we don't use it all the time, but going against the wind, use trolling motor to go with the wind.

Pulling crankbaits for crappie, it doesn't get any better than that.
 
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