200hp HPDI engine steam, and miss

[99yam40]

looking at plug wires and testing them are 2 different things.
also you did not comment on the testing in neutral or not

have you compared the reading of the 2 motors to see if and what all are different?

[SJCJACKST]

No testing of the plug wires/caps However ALL 6 plugs appearance are the same (oily/black). Yes, the readings of the starboard engine are all fairly close to the port readings above. Starboard engine runs noticeably better.....

A friend tech ran the YDS, I wasn't on scene. Presume it was tested in drive

[walleye1]

To test the plug wire caps, you will have to unscrew them from the plug wire. Then ohm test them, yamaha had some bad ones back then.

[99yam40]

If it was tested in gear and still was not firing all of the plugs, there is a problem like Rodbolt said

[SJCJACKST]

Wallleye, there was a problem with conductivity of the caps themselves?? easy to test, of course. Thanks much

[SJCJACKST]

End of summer update.....well, after hauling the boat out of the marina, and taking it to an Authorized Yamaha Service Center....diagnosis continued.... Eventually replaced six (6) injectors with rebuilt ones, a new oil pump, etc. Finally, I insisted we pull the power head to try to track down the steam issue. After much debate, the power head and entire exhaust system were pulled.....and every part was corroded to the point of large perforations (holes between the gas plenums, and the cooling jacket.... I located good, used parts and had them reassemble.... still steams, but less. I give up!!