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Thread: Merc 2.5 dies without any warning??

  1. #1
    My 2.5 keeps dieing? When im going down the river it just dies. It acts
    like some just turned the key off. It is a little hard to start afterwords unless
    I let it sit a few minutes then is starts no problem. It happens anywhere from
    idle to wide open. Does anyone have any suggestions....this is killing me I
    cant seem to figure it out???
    Any hepl would be appreciated!!

  2. #2
    I have a simular problem. I am running a A10 box and svs intake. My motor will shut off atomaticly also just like you turn off the key. But, right when it turns off if i play with the throtle back off it and give it alittle it will fire right back up, not even having to turn the key. I belive it is a vacum problem Ive heard that the svs style intakes sometimes have vacum problems. I have been through 5 differnt efi's all of them do something different. But, each one may do something different when there is a vacum problem. I have also changed everything from switch boxes to staters, coils, wire looms, rectivefires, anything that you can think of I have done and changed. Leading back to posiblity of vacum to the efi. Thats my next thing that Iam working on. So dont feel to bad you ant the only one having messed up problems. Your motor might not be the same problem, but I would check everything it might be something small and stupid like a vacum problem. Sorry for not helping more. Good like with the trouble shooting.

  3. #3
    Tom Brown
    Have you pulled a plug right after it dies?
    If the plugs are wet with fuel, it's probably a spark problem. If the plugs are dry, it's probably a fuel problem.

  4. #4
    Tom I have not tried that ... I will give it a try and see what they look like.
    Chris....Thanks for the info but I am already familiar with your problem...
    this is Ed....I talked to you all last weekend about it. :rollside:

  5. #5
    Ed whats up man, I didnt know that was you. Where did you get blueduck from? When are you going to the river again? I have a efi box that we can try on your boat just to see. If its dieing like you say it is, then it really wont be a fuel filter or a stater, or switch boxes. Its sounds like you efi is shuting off. Reason for this, is if it was one of the others it would just knock off silenders not kill the hole motor. Give me a call when you get a chance.
    cell # (760) 427-7535

  6. #6
    i jsut went through a very similar situation with my 300X which turned out to be a loose pin in the wiring harnesses
    hope this helps

  7. #7
    Hot Shot Merc
    If you have switch boxes it must be a 260 2.5 then it could be the harness.Zip tie the plugs together so it cant wiggle loose.If its a 280 its the fuel pump.It will shut the motor down without the correct pressure.

  8. #8
    Hey Chris I will give you a call.
    F26 I saw and read your post but I thought it sounded like yours was doing
    a little something different.
    HOT SHOT my motor is a 1995 2.5 200hp efi....does it have a harness like
    the 260 you refered to??

  9. #9
    The Ecu for you efi most likely has a short in it. This is very common. Injector drivers short out and this makes the motor die. I work on alot of these motors and see this same problem many times a year. You can get a reman ECU from a merc dealer or send it to Shawn at Repair Inc for repair. New ECUs are very spendy so either of these will be your best bet.

  10. #10
    Hot Shot Merc
    Yes it still has the harness that can get loose but there also might be a short in the computer like stated previously.Run the motor on the trailer and wiggle the harness in the engine cowl on the right side where it plugs together and see what happens.

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