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Dominick
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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I have a 1998 25 hp, it starts fine, idles fine. When I put

Customer Question

I have a 1998 25 hp Johnson, it starts fine, idles fine. When I put in in gear it will not open up. (About 25%) . Put in in netural and it will open wide open. ????
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

The engine will rev with no load even if it is running on one cylinder but will not with a load. We need to do a spark and compression test. The compression must be 90+ psi with no more than 15% difference between cylinders. The spark must jump a 7/16" gap on a spark gap tester. Now since the engine runs you can check for spark by removing the spark plug wire from each cylinder.You should hear the engine rpms change and hear the spark jump or crack when you remove the spark plug wire from the spark plug. The compression has to be tested with a compression gauge.

Can you do these checks and post back with findings?

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