Idle Change - 200 EFI

[nitro24]

I have a 1997 Mercury 200 EFI. One day when I cranked the motor I could tell it was idling much rougher than normal. It won't die while idling, but sounds really rough. I've had the boat in the shop recently and was told that everything checked out--compression, spark, fuel lines, switchbox, trigger, etc. Everything runs normal at higher RPM's.

Any thoughts on why my engine doesn't run as smoothly anymore?

Also, I've had the motor die suddenly while running on plane two different times. When I cranked it again the idle RPM's were jumping around without me touching the throttle.

Thanks for any help!

 

[Faztbullet]

Re: Idle Change - 200 EFI

It sounds like you have a injector/s problem,fuel pump failing(shut off) or ECU problem(shut off/erratic)or ECU harness is loose(twist connection).Also do you have a battery guage and is it over charging? I ask this as I have seen the ECU act goofy if it has a bad rectifier on a dual set-up. You can send the ECU in to be checked and injectors cleaned which I suggest needs to be done ever 2 years with todays fuel..

 

[nitro24]

Re: Idle Change - 200 EFI

When I had the boat in the shop recently for an acceleration problem they checked the fuel pumps and ECU without finding anything wrong. I've replaced all 3 batteries, both regulators, and the stator.

I've read about the idle control module, could this be the problem? If so, how is it tested?