6beep alarm mercury 90 HP EFI outboard engine

[migmatic]

My 90 HP Mercury EFI engine starts and runs well until I have run the engine between 5 and 10 mins. It starts to run rough intermittently for a few mins. Then I get a 6 beep alarm. If I slow down the boat continues to run relatively smoothly and if I speed up it starts to run roughly. When the boat sits over night and start it up it runs fine and goes back into the problem about 5-10 mins after running the engine. I have changed the spark plugs, the fuel filters and last night the gas float was replaced. The problem has not been solved. Any ideas?

 

[galamb]

6 beeps "on start-up OR during a running failure" indicates a fault in any of the following:

MAT sensor (Manifold Temperature), MAP (Manifold Pressure) sensor, TPS (throttle position sensor) or the ECM itself (Flash Check Summary).

You will need to get this to a shop that has a diagnostic computer (DDT) to have it plugged in to see which sensor/module is throwing a code and replace accordingly (none of these are "fixed", you swap them out but at the cost of some of the components you need to make sure which one is jiggered).

 

[migmatic]

Okay thanks for the information. I will give that a try.

 

[Jgibson36]

Hi there, I’m experiencing the same issue on my 90hp EFI outboard. Do you remember what fixed this?