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HELP! '98 250 OX66 won't fire -weird problem!

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  • #1

    HELP! '98 250 OX66 won't fire -weird problem!

    In February 2017 I replaced the low pressure fuel pumps, cleaned the O2 sensor and did some other routine maintenance on this motor. Put it back in the water and it ran great. Put it on the lift, went back about 36 hours later and it wouldn't start. Have been trying to figure this thing out since. Have had 2 different mechanics (one of which is a certified Yamaha mechanic)work on it to no avail. The 2nd mechanic got a 1,3 code with the winky-blinky tool and concluded the issue was the pulser coil. He replaced it last week (I bought it from Boats.net) but it made no difference. He subsequently determined that the fuel injectors were not firing - made some sort of a jumper wire and got the motor to at least cough - more than it's done since February. He then swapped out the resistor assembly on the injectors with an assembly off another 250 OX66 which is running. That made no difference. He concluded it had to be a problem with the CDI. Got the new CDI in today (from Boats.net), installed it and it still did not fire. What the heck is going on?!?!?!?

    Any help from the Yamaha gurus here would be VERY much appreciated! For complete context here is a list of all the things that have been replaced on this motor since last October:

    - Fuel line& bulb to H20/fuel separator
    - H20/Fuel separator
    -Onboard fuel filter
    -High pressure fuel pump & regulator
    -Stator
    -Low pressure fuel pumps
    -Plugs
    -Pulser coil
    -CDI

    ~$3500 later and I still don't have a motor that will start....and it's so weird how this cropped up just sitting on the lift.

    Surely there is someone here that can figure out what the heck is going on with this motor - please help!!

    Thanks for any insight into this weird problem that no one seems to be able to figure out.

    Tim
    Tags: None
  • #2
    did anyone monitor fuel pressures?
    or did they just throw parts at the motor and hope?

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    • #3
      Originally posted by 99yam40 View Post
      did anyone monitor fuel pressures?
      or did they just throw parts at the motor and hope?
      The 2nd mechanic told me he checked the fuel pressure during his first visit (I wasn't present that time) and that the pressure was, in his words, a bit low but not enough to be a problem. Which I thought was curious since all of the fuel pumps have been replaced within the last 6 months.

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      • #4
        you need more info from them about what all they checked.If fuel pressures were in spec why did they replace the pumps and pressure regulator

        the injectors have drivers to get them to open, but I do not know much about where they are located.
        But i would think the techs could test fire the injectors

        Comment

        • #5
          Originally posted by 99yam40 View Post
          you need more info from them about what all they checked.If fuel pressures were in spec why did they replace the pumps and pressure regulator the injectors have drivers to get them to open, but I do not know much about where they are located.
          But i would think the techs could test fire the injectors

          The tech that replaced the high pressure pump and pressure regulator was the 1st mechanic and it became clear pretty quickly he was just throwing parts at it - but that's a whole other story. The HP pump and regulator had already been replaced when the 2nd mechanic checked the fuel pressure and found it 'a bit low' whatever the heck that means. Also, he did test fire them when replacing the pulser coil didn't solve the problem and we knew there was good spark across the board. Perhaps I forgot to mention that in the OP or wasn't clear but he took a piece of romex and did something to make them fire. It was at that point that he concluded the issue was either the resistor assembly or CDI so he swapped out the resistor assembly with another one from a different 250 OX66 that is running with no success.

          Other than the CDI and resistor assembly what could cause the injectors not to fire?? Could there be some sort of issue in the wire harness from the CDI to the injectors?

          Comment

          • #6
            using a piece of romex does not sound like something a good Yamaha tech would be using.
            I would think they would have the proper tools and equipment to test properly.

            being as old as it is, I have no idea what is needed to test fire them

            wiring and connections can always fail

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