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wendell posted 10-26-2009 05:22 PM ET (US)   Profile for wendell   Send Email to wendell  
I have twin 2002 115hp mercury 4 stroke outboards. one engine runs perfect and the other is giving me problems that I acannot figure out whats 2800rpm trolling the motor starts to drop rpm slowly and loses power and die.. Also, at idle there is a distinct miss as well at higer speeds...I can start up the engine right after it dies and just like nothing had happened it will start right up without hesitation and run fine. I have swapped out the low pressure fuel pump, coils, coil triggers, fuel filter, fuel bulb, plugs, ecm, cyl pressure is all good....I do not know if the stator has anything to do with this problem any info is greatly appreciated.
jimh posted 10-27-2009 08:52 PM ET (US)     Profile for jimh  Send Email to jimh     
It is quite common that boaters refer to a component as "the stator" when actually there are several components involved. "The stator" may be an assembly that contains several coil winding:

--alternator winding for battery charging

--winding for excitation of ignition coil primary

--winding for triggering of ignition timing

The winding for the alternator can be faulty and the engine will still run normally; the battery charging current will be affected.

The winding for excitation of the ignition coil primary windings can be faulty. This will affect the engine running characteristics.

The winding for triggering of ignition timing can be faulty. This will affect the engine running characteristics.

Obtain the service manual for your engine. There generally will be test procedures for checking the several windings of "the stator." Typically there are resistance checks and continuity checks that can be made when the engine is not running. There are also voltage measurements to be made when the engine is running.

Chuck Tribolet posted 10-28-2009 08:30 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
The good news is you have a full set of functional parts on
the other engine.

This smells like a fuel supply problem to me. It gets enough
gas to run at idle, but at higher RPMs the fuel supply system
isn't delivering enough gas and things run dry.

Is this EFI or carbed? (Sorry, I'm an OMC guy).

Try this: Create the problem, but have a buddy pump the bulb
like crazy. If the problem doesn't happen, you know you have
a fuel supply problem.

Trolling at 2800 RPM? That seems like a rather high RPM for
trolling, but I don't fish.


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