2003 Mercury 250XS Stalling When Under Load

Discussion in 'Performance Outboard Motors' started by JWolff, Jul 6, 2017.

  1. JWolff

    JWolff Active Member

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    This is a continuation of my stalling issues on my Merc. If you remember the story skip to the attachments and let me know if the diagnostic results show anything that jumps out at you. If you don’t remember my story, read below.

    My 2003 Mercury 250XS has been stalling out for the past year and I am at my wits end trying to figure out a solution. Two separate shops have looked at it. First shop found nothing wrong. The second shop put it on the river and got the issue to repeat while hooked up to all their instruments. Attachments below are the paperwork I got from them showing the codes.

    Thinking it was fixed, we took it out this weekend while on vacation and it worked fine in the morning (about 15 minutes of running on plane on a little 1000 acre lake) but then we started tubing in the afternoon and it died twice (about 30 minutes of pulling the tube). No alarms, no warning, just dies. Like if you turn off the key or pull the kill switch. Hoping it was a load issue we tried boating around at approx. 35mph with just the family in the boat (less than 2 miles). Died again. Got back to the dock and let it sit for 3-4 hrs. Went out again to take the boat to the ramp with just me in the boat and it died 2 more times going about 1 mile across the lake. Boat starts right back up and idles with zero issues.

    Replaced the battery over the winter with an 1150cca AGM.

    Humminbird reads 13.8V when running the motor.

    Shop 2 replaced the trim relay since that was the main fault they found. Shop 2 also said fuel pressure is good so they don’t believe it is degraded fuel lines being clogged by ethanol fuel (which is what I was thinking the issue was). Found no loose wires.

    Any other ideas?

    Also, the “frequency counter” on the diagnostic print out is how many times the issue has happened, correct? Because the top two faults have a count of 128 and 121 times they have happened with an engine state of “stall”. It has not happened that many times to me over the past year. Starting to wonder if someone dumped their problem child on me since they couldn’t get it fixed. Engine had 88 hrs when I bought the boat. 117 hrs now. I am the 3rd owner. Love the hull but really starting to dislike Mercury.
     

    Attached Files:

  2. Tim Powell

    Tim Powell Active Member

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    131 is a faulty trim sending unit or a broken wire in the circuit. Do you have a 2 wire or 3 wire trim sensor? Its located on the port side of engine near clamp pivot point.

    104 is a faulty or disconnected lake/sea water temp sensor...you probably don't have this feature...most bass boats don't. It shouldn't cause your problem.

    75 is a fuel sending unit, do you have analog or digital gauges?

    82 is for the oil tank sending unit...you probably to not have the fuel/oil/paddle wheel harness....this would explain 75 and 104 as well.

    2 is low voltage, and that happened 5 hours ago....have yo confirmed that your "new" battery is good? Have it load tested if not. Low voltage will cause all kinds of crazy issues.


    Nothing just jumps out at me in the freeze frame printout.


    When was the fuel filter last replaced? Did anyone look down into the VST housing where the filter goes? If so, was there any debris in the bottom?

    The pulse pump will cause them to die at idle.
     
    Last edited: Jul 6, 2017
  3. bassracr

    bassracr Active Member

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    fuel.jpg


    we had one that acted similar , replaced the pulse pump and filter, and was disappointed when they looked good ,because i knew that was not the problem..when i cut the fuel hose ..different story. tapped on it and all kinds of crap came out. replaced line and bulb and all the problems disappeared .
     
  4. Tim Powell

    Tim Powell Active Member

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    Thats why I asked if anyone looked into the VST when the filter was changed.
     
  5. bassracr

    bassracr Active Member

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    I included the picture to illustrate your point. When I read your reply I was thinking Tim is on to something.. we recently went through the same issues and was happy to get it resolved
     
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  6. JWolff

    JWolff Active Member

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    The fuel lines are my thought too but they say the fuel pressure is good. Would fuel pressure check be able to find the clogged filter/line/pump or is the pressure taken farther up stream and just proves the fuel pump is working?
     
  7. GotMyAlly

    GotMyAlly Well-Known Member

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    Did they check the fuel pressure at idle? Or at speed?

    Another thought - anything in the tank that may be moving around and blocking the fuel pickup?
     
  8. JWolff

    JWolff Active Member

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    Having them replace the fuel lines, fuel filter, and check the other things related to fuel. They are thinking it might be the ecu being intermittent and shutting down fuel flow.
     
  9. JWolff

    JWolff Active Member

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    Neal,
    They said the gauges showed all good on fuel pressure even while at speed. Because of that they were very resistant to change it out. I told them to just do it so it is one less thing to question.
     
  10. Tim Powell

    Tim Powell Active Member

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    Any updates?
     
  11. JWolff

    JWolff Active Member

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    Not yet. Found whipple superchargers and simon motorsports for ecu repairs if the fuel line stuff doesnt fix it. Any body have experience with either of the above. Whipple calls out fuel pump shutting down as a common issue with my ecu.
     
  12. Jr in Jax

    Jr in Jax Active Member Supporting Member

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    My ECU before I went to an ACU had the fuel pump problem.
     
  13. JWolff

    JWolff Active Member

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    Update: fuel lines, pulse pump, fuel filter all changed out. 10 minutes into pulling the tube, shut down again. I removed the ecu and plan on sending it to simon motorsports tomorrow. Hopefully they find something.
     

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