idles rough

[johndoe]

2004 Merc 6.2L MPI with Bravo 3.
Engine runs great, but at idle it, in neutral, it seems to have begun running a bit rough, and when shifting into forward gear, (first detent) sometimes it dies, but restarts immediately, sometimes it fees like it is not in gear, but boat is moving. When I press down for a little more throttle, it slams into gear... with a clunk, even though it is already in gear.
Could it be a simple idle adjustment, or a throttle cable problem... I checked and lubed the cable(s) per the manual (#28) but still has same problem.

Also wondering about one of these code scanners... Will the OBD code scanners work on this motor?

 

[JustJason]

Re: idles rough

When was the last time the motor had a complete tune up?
What are your in gear and in nuetral idle rpms?

For a code scanner you need a marine specific one. Google Rinda. OBD is the language cars use, boat engines use their own propietrary MEFI language.

 

[havasuboatman]

Re: idles rough

You also want to check your water separater. End of the season and all you may have some water in there. Once the water reach's a certian point it will effect engine performance.
Pull it off and dump it into a clear container. Check for water. Do not reuse the filter. fill the new filter with gas before putting it on.

 

[johndoe]

Re: idles rough

Not sure what a "tune up" on an MPI engine consists of, but recently, the plugs, pcv valve were replaced. Perhaps it time for the plug wires, rotor and cap...etc.
The fuel/water separator filter was replaced last season as well as the in-line fuel filter.... hmmm good be bad gas.

the code scanner was just to see what it costs to read the codes... Do you know of a less expensive alternative?