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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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Last year before I put the boat away winter I had a new

Customer Question

Last year before I put the boat away for the winter I had a new tilt/trim switch put into the shifter handle. The marine mechanic told me that he had to adjust the cables in the shifter. This past spring I am only getting 3000 rpms when the throttle/shifter is all the way forward-down. When I am in neutral and I move the lever on the shifter box upward I get full rpms 4400-5000. Why am I not getting on plane or the needed RPMS with the throttle arm shifter in the full forward position? The boat has a quick silver shifter and an 80 hp 2 cycle Mercury outboard.
Submitted: 11 months ago.
Category: Boat
Expert:  Tan replied 11 months ago.

Hello. My name is Tan.

We need to start with a spark and compression test. The spark must jump a 7/16" gap on a spark gap tester. The compression must 90+ psi on all cylinders with no more than 10% difference between cylinders.

The engine in neutral will rev all day long up to wide open throttle with no load. It could be running on 2 cylinders and would turn up to wide open throttle. So in neutral is not a test and this is a good way to blow your motor up. Would you get in your car and with in neutral push the gas pedal to the floor?

The chances are you have an engine run issue not a control issue. To be sure the control isn't the issue put the throttle to wide open engine off. Now look down the throats of the carburetors is the throttle plate full open? If yes then control is fine.

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