1985 Mercury 7.5 full speed problems

Discussion in 'Outboards' started by kenrahe, Jul 23, 2011.

  1. kenrahe
    Joined: Apr 2010
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    Location: pomfret ct

    kenrahe Sunseeker

    Having problems with running at high speed replaced fuel pump kit and it runs at full speed for a while then bogs down and runs shitty then dies start it back up and does the same thing again...took carb apart when first got it and cleaned bowl and jets but did not take carb completely apart...any ideas will be greatly appecated....
     
    Last edited: Jul 26, 2011
  2. El Sea
    Joined: Aug 2006
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    Location: St Petersburg, Florida

    El Sea Junior Member

    How old is the fuel?
     
  3. kenrahe
    Joined: Apr 2010
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    kenrahe Sunseeker

    the fuel is about 2 months but someone told me to put a fuel addittve that he said will help the fuel pump before that didn't work so i replaced the diaphram with a fuel pump kit...also i'm not sure of the year i can't find any numbers but on the side plate of the power head it say's kiekhaefer lighting......
     
  4. pistnbroke
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    when it goes shitty pump the primer bulb ..if it picks up you still have a pump problem /line blockage/tank vent ..
     
  5. kenrahe
    Joined: Apr 2010
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    kenrahe Sunseeker

    tried that but it does not change anything and bulb is nice and hard
     
    Last edited: Jul 24, 2011
  6. kenJ
    Joined: Jul 2005
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    Location: Williamsburg, VA

    kenJ Senior Member

    Might be an air leak. Check the connection where the fuel hose attaches to the engine. They eventually get loose and allow air in. Might also want to put some Seafoam into the gas. Run the engine for a while, then let it sit. Seafoam was designed to clean deposits out of carbs. The engine will smoke until the seafoam is gone.
     
  7. kenrahe
    Joined: Apr 2010
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    Location: pomfret ct

    kenrahe Sunseeker

    i throughly cleaned the carb but i noticed the float is very pourous so i ordered a new one but another thing i noticed is when it's running the water seems to get hot right away an when it stalls it pop's a little through the water discharge.it's got a brand new impeller in this year....
     
  8. kenJ
    Joined: Jul 2005
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    Location: Williamsburg, VA

    kenJ Senior Member

  9. kenrahe
    Joined: Apr 2010
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    Location: pomfret ct

    kenrahe Sunseeker

    Yes water is pumping through the powerhead but is always hot from the very start and it has no thermostat is it always hot because of being 2 stroke my 4 stroke nissanstarts out cold and always runs barley warm how can i check the reeds with the carb off i can see they are inside the powerhead and it looks like they can only be accessed by taking it apart...and how do I attach a pictur to show everyone what I'm talking about
     
  10. kenJ
    Joined: Jul 2005
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    Location: Williamsburg, VA

    kenJ Senior Member

    A bit confused. Looking at the '85 7.5hp manuals on the Crowley Marine site indicate all models have a thermostat. Are you sure you don't?

    Are you getting water out the exhaust? Maybe something in the cooling system is plugged up.

    The fact that it runs for a while would indicate to me that the reed valve is ok.

    I think you have a couple things going on. One with the fuel and another with the cooling. I would get the cooling fixed first or you will end up frying the engine once the fuel problem is licked.

    I run a 5hp 2 cycle. Water out the teltale takes quite a while to heat up, should be no difference between 2 cycle and 4 cycle.
     
  11. kenrahe
    Joined: Apr 2010
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    Location: pomfret ct

    kenrahe Sunseeker

    how do i attach a photo and i'll send you a picture ...the person said it was and 85 but the motor says Kiekhaefer lighting on side plate and i can fin no serial number
     
  12. kenrahe
    Joined: Apr 2010
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    Location: pomfret ct

    kenrahe Sunseeker

    when i try to add a photo it asks for an url not from my documents
     
  13. kenJ
    Joined: Jul 2005
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    Location: Williamsburg, VA

    kenJ Senior Member

    Photos

    Push the add a reply button, not the quick reply.

    After you type in your note, scroll down to the manage attachments button.
    Push it. use the browse button at the top to find your pictures, when finished, Upload them. Max size of a .jpg is 2mb, you may need to compress them. Other formats have different sizes, there is a chart that shows.

    Just saw your other note. Not sure. When I hit the browse button I get a windows explorer type window, it does not ask for an URL.
     
  14. kenrahe
    Joined: Apr 2010
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    Location: pomfret ct

    kenrahe Sunseeker


  15. kenJ
    Joined: Jul 2005
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    Location: Williamsburg, VA

    kenJ Senior Member

    I can't open photobucket at work.

    Looking at a couple of Mercury history sites, looks like the Kiekhaefer name came off the engines in the early 70's. Looks like the PO was a bit misleading.

    Might want to change the title of the thread to Kiekhaefer Lightning help, there are a couple folks on the board that really know the old motors.
     
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