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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4716
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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Jeff I have a 1976 85 hp 850 mercury outboard motor.It starts

Customer Question

jeff I have a 1976 85 hp 850 mercury outboard motor.It starts easy idle fine .when I shift it in gear it stall out.if you turn up the throttle be real easy on pushing it forward it will gradual move out you can open it up all the way.runs like new.what cuses the delay.
Submitted: 1 year ago.
Category: Boat
Expert:  Jeff G. replied 1 year ago.
Typically there is a bog from a lean condition in the midrange. The high speed doesn't have an adjustment, you have a fixed jet in the carb. The low speed has an adjustable mixture, the slotted screw near the top front. At a point, around 1800 rpm or so the engine switches over form the low speed to the high speed side of things. If during this switch the carb is too lean it will bog down and most of the time stall.Sometimes you can test for this by hitting the choke quickly and if it goes on you know it is too lean on the low speed.Just when you get the low speed adjusted for a really great idle you run into this.The fix is to run the low speed mixture slightly on the rich side. The idle won't be as good but will be fine, you won't stall.To do this adjustment take the engine cover off the front. Using a long skinny slotted screwdriver adjust the idle mixture screw out about 1/8 turn on both carbs. Then see if the boat will get on plane. If not then repeat the richening of the idle mixture. You should find a happy medium.Try this and post back how it goes.

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