Buy Yamaha Outboard Parts

Announcement

Collapse
No announcement yet.

250HP OX66 O2 Sensor and Timing

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 250HP OX66 O2 Sensor and Timing

    Hello everyone, new to the forum. I usually post in another forum but figured I would also ask here since its geared towards Yamaha engines.

    I currently have an 00 250HP OX66. Currently it has sort of a “lean sneeze” and surging around 2200-2500 RPM. Since everybody says to check the O2 sensor, that’s where I started. I did the idle/cover hole on intake test and recorded a little video. How fast are the numbers supposed to move within the range? Should I clean/replace sensor?

    https://youtu.be/KZ-lGlqkDak

    Second question is about timing. Don’t have a winky blinky so wanted to confirm if I had a bad sensor and timing was off. I know its supposed to be at 7*ATDC if its running correctly. There are two ranges on flywheel (negative and positive). Where exactly is 7*ATDC? My timing is currently at the orange line (750-800 RPM):

    47EF9CD5-97D0-40AE-9BA1-9D03B28BF180.jpeg
    ​​​​​​
    Things I’ve done:

    -Replaced VST filter
    -Replaced LP fuel pumps
    -New Spark Plugs
    -Tested Coil Caps
    -Cleaned Injectors
    -Adjusted Oil link
    -Decarb “Dunk” Method with seafoam
    -Checked gas (no water/non-ethanol)
    -Swapped Stator/Pulsor coil from spare engine
    -VST has fuel pressure under load (35-36PSI)

    Thanks for any help or info provided,

    Jay

  • #2
    Forgot to mention that the timing goes to the left of 1TDC and rpm increases to 1200 when I disconnect knock sensor. So I'm assuming my timing is correct (so to the right of 1TDC is ATDC and to the left BTDC).

    Comment


    • #3
      that sounds correct to me

      Comment


      • #4
        Originally posted by 99yam40 View Post
        that sounds correct to me
        Thank you for the reply. Any guesses on my O2 specs from video? I had read it was supposed to go down to .3 and up to .8 fairly fast when I would cover the intake hole.

        Comment

        Working...
        X