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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11050
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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My boat will not go over 2000 rpm what can cause it

Customer Question

my boat will not go over 2000 rpm what can cause it
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.

Hello. My name is Tan.

The most common cause is fuel starvation due to dirty fuel oer debris in the fuel tank. Then the next is loss of spark and loss of compression. These are the 3 things you need for the engine to run correctly. Fuel, spark and compression. If you have all 3 the engine should perform properly.

Fuel starvation is where the engine isn't getting enough fuel volume to get the extra rpms and horse power. Loss of spark just causes one or more cylinders not to fire. Making the engine weak or low on power. As for compression fuel can't combust unless it is under pressure. No compression no power no rpms.

So your first step to diagnosing the problem is a compression and spark test.

To test for a fuel starvation issue run the engine on a different fuel source this will eliminate the boat side fuel system as a cause for your issue. If it runs better then the boat side fuel system is the problem. If no change then you have an engine related issue.

Customer: replied 2 years ago.
The eng runs good but I removed the eng cover to check the carb and at full throttle the 4barls don't open if you open them by hand the boat will pict up a bit more speed
Expert:  Tan replied 2 years ago.

Could I get the make model and serial number of the engine you are working on please?