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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15922
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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My 40 hp mercury run fine at near wide open minutes then

Customer Question

my 40 hp mercury run fine at near wide open for 5 minutes then starts beeping and goes into slow mode.
have changed the water pump and have checked the thermostat in hot water. we thought it was over heating due to porr discharge but since changing the water pump discharge stream is fine.
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** I will be helping you today. All Mercurys are cataloged by serial number, can I get that number. Next, is it a solid "BEEEEEEEEEEEEEEEEEEEEEEEEEEEP" or is it a series of beeps over and over, like a beep beep beep?
Customer: replied 2 years ago.
1c018405 its a soild beeeeeeeeeep
Customer: replied 2 years ago.
you can run wide open for about 2-5 min then it beeeeeeeeeps un till you let off the throttle
Expert:  Jason replied 2 years ago.
Got it.
The solid beep is either low oil pressure, or engine overheat, or a bad sensor respectively fooling the engines computer to think one of those scenarios is happening. If you have the ECM scanned with a scan tool there will be a record of which one it is.
In the field what I do is I do hook up the engine to my laptop and I see if it has a record of overheat or low oil pressure. Depending on what the laptop says I go an run the engine and test what I need to. For example, if the laptop says overheat, I run the engine and duplicate the problem and scan engine temps manually with an infra red temp gun. If it's hot then I work on the overheat issue. If it's normal temp, I replace the temperature sensor. If the laptop comes back and says low oil pressure. What I do there is remove the engines oil pressure switch and plumb in a mechanical gauge, and go and run the engine and see if it has acceptable oil pressure or not. If it does, I replace the oil pressure switch. If it does not, I change the oil and filter and say a little prayer for the customer that it's just a clogged oil filter and nothing worse.
And that's about it. That is what needs to be done. Does that all make sense? I do want to make sure you are happy with the service I am providing to you before you go. Did you have any other questions on the engine or do you think that covers it?

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