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  1. merc850

    1977 merc 150 outboard bogs at WOT

    DON'T scream it in the driveway with muffs! You have to set the low speed needles to 1 1/4 turns out in F in the water underway @ 800 rpm.
  2. merc850

    1979 40hp lower unit stuck

    I have 7 old Merc's and I've never had anywhere near the problems you've had; what an ordeal! The driveshaft with the pin forces the tapered bearing together - the one without uses a ball bearing like the older ones. The O ring on the shaft is there to prevent water from entering the crank...
  3. merc850

    1979 40hp lower unit stuck

    That pin is a bearing pre-load to keep the tapered bearing in the lower unit tensioned, if you cut it off everything goes to hell.
  4. merc850

    1978 mercury outboard

    This is your wiring layout
  5. merc850

    89 Mercury outboard 100 hp shift shaft alignment

    Does it shift correctly? Turn the prop while shifting into reverse.
  6. merc850

    89 Mercury outboard 100 hp shift shaft alignment

    If you can tilt the motor up, it makes the gearcase lighter - try to get it as horizontal as possible, since you don't have the manual reverse lock installed you will need to grab the shift shaft with a needlenose plier and move it into place Some driveshafts have a pre-load pin that gives some...
  7. merc850

    7.5 mercury comet/lightening setting 30 years

    The wiring looks good, the fuel lines look good - I would replace the impeller (the serial Nr. makes it a 1972 model) check for spark and see if it runs. I've run many motors in worse condition.
  8. merc850

    7.5 mercury comet/lightening setting 30 years

    Plugs: SPARK PLUG - CHA833 (L78V)
  9. merc850

    1998 40ELPTO gear oil from weep hole?

    Looks like it could only be water coming from that area, does it smell like a hi-sulfur content liquid like gear lube?
  10. merc850

    Spark Plug Half-Fouling

    Looks like a weak spark caused by failing stator or trigger. See if the spark will jump a 7/16" gap. Do not use regular reach plugs unless manual says so, they will hit the piston top.
  11. merc850

    No spark on Merc 85hp

    Are you following these steps? https://forums.iboats.com/threads/starting-a-2-cycle-merc-verified.670882/
  12. merc850

    1968 20hp lower unit seals

    A manual would help but in lieu of one I'm posting some starter pages: (before you start soak the cover nut area with a penetrating oil for a few days too loosen it up.)
  13. merc850

    No spark on Merc 85hp

    One marine starting battery not a deep cycle one.
  14. merc850

    Waiting to launch

    Almost launch time (except in canada) and many guys will be changing their impellers re-installing their lower units and having shift problems: This is how I do it in about 60 sec.: Turn the LU shift shaft by hand counter-clockwise until it stops, then with Vise Grips tight on the bottom of the...
  15. merc850

    No spark on Merc 85hp

    If you put a voltmeter on the + starter terminal and the cowl ground read the voltage while turning over the motor, it should be 10-12 volts if your battery is good. If it does fall in this range your starter probably needs rebuilding/cleaning (brushes). A small engine electrical shop could fix...
  16. merc850

    Merc outboard serial number question

    Good that you've worked on one before so you know the plug wires screw into the cap, CDI has the engine harness https://www.cdielectronics.com/product/414-2770/, or Marine Engine.com I bought the last one Mercury had this year
  17. merc850

    1965 3.9hp plug fouls

    I don't know what brand of oil you're using but I've found that Amsoil synthetic smokes less and if you live in the US you can get 100:1 blend which lets you go from 50:1 to 100:1. I was mixing it at 70:1 and of course I used less oil and reduced smoking.
  18. merc850

    Merc outboard serial number question

    i think you should rewire it - there seems to be some incorrect connections and corroded wires which can cause a major fire. I am wondering about the connections on the terminal block in image 2 they look like they are coming from the stator but one disappears into the cowling and one is...
  19. merc850

    1965 3.9hp plug fouls

    The Nr. refers to heat range - The middle number indicates the heat range of the spark plug, the higher the number the hotter the heat range the hotter the plug the less it will foul.
  20. merc850

    1965 3.9hp plug fouls

    According to the Merc manual the 1964-66 3.9's used a J7C plug and the gap is .025"/ the points should be set at .020". Your motor falls into those years.
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