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Motor often cuts off when engaging gear

O

osifuentes

New member
I have a 1986 75hp Mercury outboard 4 cyl. Whenever I start the motor it will idle just fine. My problem comes in when I go to put it in gear it will shut off unless I give it a bit of gas. I am not sure if the idle screw needs adjusting or if it is something else causing this. Any suggestions on what the problem may be and how to fix it would be appreciated. Thanks
 
It will run on 2 cylinders. Verify that all cylinders are getting spark...it needs to be a loud snapping blue colored spark that will jump 7/16" gap. White, yellow or orange colored spark is too week to fire the cylinder. Get a spark gap tester at an auto parts store so you can see the spak from each cylinder at the same time to compare them to each other.
 
You need to readjust the idle mixture screws.

Warm the motor with the boat on the trailer or tied to a dock.

Turn the idle screws out a 1/2 turn.

Put it in gear anyway you can and idle it up enough to keep it running. SLOWLY make an adjustment, 1/ 4 turn at a time, letting the motor settle in a few seconds at each one.

When you have found your best idle setting for both carbs, open the mixture screws OUT 1/2 turn and go boating.

Jeff
 
Jeff :
I only have a hose flusher for the 75 horse power boat motor , Is It safe to put the motor in gear to check the idle using the hose flusher ? I have located ONE carb, Where is the other one?
 
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