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Joe
Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7136
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
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I have an ongoing problem with my 2012 Mercury 90 HP 4

Customer Question

I have an ongoing problem with my 2012 Mercury 90 HP 4 stroke EFI engine. It will run fine for a while and then all of a sudden it makes a high pitch sound and loses all power. I have to put the boat in neutral and then after a few minutes I can coax it to run again but cannot ever get it above 3,00 rpms. I have taken it to the dealer numerous times and they cannot seem to find the problem. I am about to see them again this Friday to take it out so they can see what it is doing but I need to understand what the root cause is. I see that this is an ongoing problem for others on the web so was hoping you could help. The motor has a 5 year warranty on it.
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
Are you still working on an answer?
Expert:  Joe replied 1 year ago.

Hello,

Thank you for allowing me to assist you, my name is Joe and I will be happy to assist you with your concern today.

I am just seeing if you still need assistance with this problem? The reason I ask is because I see that your question has not been answered sooner and I wanted to make sure if you still needed help.

In some cases a question may sit due to several different reasons. My objective that I wish is to make sure that if you still need help that I can at the very least reach out to you and attempt to help you.

At this time please feel free when you are ready to reply back to me and ask to continue working with me, another expert or if you no longer need help please just let me know exactly what you wish to do.

If you need any further assistance you can reply back at any time for my help.
I'd be happy to answer any other questions you have even if not related.

Thanks,
Joe

Customer: replied 1 year ago.
No one has answered yet and I still need assistance.
Expert:  Joe replied 1 year ago.

Once it stalls it cannot be restarted right away, correct?

If so have you then checked spark, compression (hot), and fuel pressure?

Thanks,

Joe

Customer: replied 1 year ago.
Most of the time i can get to neutral and the engine keeps running. Just does not let me get above 3k rpm before it sputters again.
Expert:  Joe replied 1 year ago.

So it does not stall?

Have you checked for misfires (timing light), fuel pressure during the problem and hot and cold compression?

Thanks,

Joe

Customer: replied 1 year ago.
They have checked all those things. This engine has less than 50 hours so it is essentially new. There are videos on youtube with the exact same motor doing the exact same thing but could not find the answer to the cause.
Expert:  Joe replied 1 year ago.

What exactly has been tested/check and replaced already?

Customer: replied 1 year ago.
I know the have replaced the fuel pump and have hooked it up to their diagnostic computer
Expert:  Joe replied 1 year ago.

Are you trying to fix this yourself or just have an understanding of the problem? I have a feeling since it is under warranty that you are not trying to fix it. The problem is that while there are always things online that can be found it doesn't mean the solution is always the same and testing must be done to correctly diagnose the problem, this does unfortunately mean the only way to find the problem is with testing. With the scan tool connected the dealer can evaluate things that without are not as easy and or cannot be done esp all in one location, these newer engines really require this for proper diagnosis with certain problems esp when it is not the basics. They would be going in and viewing many many different sensors and seeing how the engine is responding, they can also run tests and evaluate via the tool.

Thanks,

Joe

Customer: replied 1 year ago.
Not trying to fix myself but this seems to be a common problem and i want to have an understanding of what it could be.
Expert:  Joe replied 1 year ago.

Unfortunately that is what I was explaining, which is that there is no 100% way to know what the problem is without proper testing and diagnosis and thus why I started off asking about testing things for me as that is the only way. I can assure you that it only seems common because a few others have wrote about it online, if it was that common there would be an tsb and or would be able to have already been fixed by now.

Thanks,

Joe

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