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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 1990 Evinrude XP 150 on a 18ft. Bass Cat boat, the

Customer Question

I have a 1990 Evinrude XP 150 on a 18ft. Bass Cat boat, the over heat horn will come on when I go full throttle and motor will start cutting out till you let it cool down. It idles great and mid range speed its ok. But if I really get into it the horn comes on and it cuts the power down. Can you give me an idea what is causing this?
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

This may take more than one reply to solve your issue.

This is caused by over heat or a fuel restriction. If the alarm shuts off as soon as you back off the throttle it is a fuel restriction.

Run the boat till the alarm sounds then squeeze the primer bulb does the alarm quit and the engine smooth out?

The other option is to run the engine on another fuel tank to eloiminate the boat side fuel system as a cause for the issue.

This engine has a vacuum switch that will sound the alarm if you have a fuel restriction. This is designed so you will slow down and prevent burning a piston.

If the engine run better on the other fuel tank then you have a fuel restriction in the boat side fuel system. Either debris in the tank or a bad fuel line or possible vent clogged.

Now if the alarm continues even after you have backed off throttle then you need to service the water pump, thermostats and the pressure relief valves.