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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11052
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have a 1978 omc 115,motor will run on ears perfectly,when

Customer Question

I have a 1978 omc 115,motor will run on ears perfectly,when in lake dies when put in gear.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.

Hello. My name is Tan.

This is most likely a carburetor issue possibly spark.

We need to check spark on all cylinders with a spark gap tester. The spark must jump a 7/16" gap on the tester.

Now when you are running the boat have you tried choking the engine when getting on plane?

Have you tried squeezing the primer bulb when getting on plane or throttling up?

You have eliminated the compression as a possible leaving spark or fuel as the cause of the issue.

There is one other check you can do if the boat is on a trailer. Remove the bottom drain plug # ***** on the top carburetor then remove the jet # ***** with a very small slotted screwdriver.. Both should be shinny brass color.

The high speed jet is in the bottom of the carburetor and if the boat has been sitting for awhile the jet will clog with old fuel residue and cause the exact symptom you are having.

Do these checks and post back with findings.