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  1. merc850

    08' Merc 90hp --Ditching The Oil pump/going mixed fuel..

    If you don't have a tach get one and make sure the motor is running near the hi end of its operating range at full throttle.
  2. merc850

    Mercury adjustment question

    Usually you have to have the motor running to shift into reverse, on land you turn the prop while shifting to line up the shift "dogs".
  3. merc850

    Mercury Mark 20

    Maybe someone has already changed it or Mercury dealer did, the serial Nr. is what you use for parts ordering and a service manual. The Nr. makes it a 1954. Remove the drain screws in the LU and see what comes out.
  4. merc850

    Mercury Mark 20

    The early versions used a 2 hose fuel line, the crankcase pressurized the tank which pushed fuel into the carb; this can be changed to a single line like the later ones - ask these guys http://johnsoldmercurysite.com/phpBB3/index.php?sid=c1eedb7960442074f2594ee023b0274f one important note: the...
  5. merc850

    Mercury 402 40hp 1970s prop unit removal

    I had the same problem with my 850, the carrier would not come out and the housing was damaged trying to remove the internals; I used a cutoff wheel to cut it in half and saved the gears and propshaft to use in another case. Another way is to buy a complete dead motor with a good LU.
  6. merc850

    Power Trim (A-45194A13) Question

    According to the manual "The reverse lock knob must be turned fully to the left before uncapping valve ports or oil will drain from the pump"! This is for removing the lines. You could also remove the cylinders which is what I'd do as it is easy. You could undo the lines from the cylinders and...
  7. merc850

    1973 85 hp Needs Ignition Help

    Here's the wiring diagram for the 4 cyl. engines, the BROWN terminal is for the Merc tach [NLA] check the timing belt to see if it is OK ie; turns the rotor, don't pull the plug wires out of the cap - they screw in. Do not try to pry off the rotor in the dist. it is molded on - you can clean the...
  8. merc850

    Mercury 402 40hp 1970s prop unit removal

    Here's a still from a video I shot of my 850 running in forward.
  9. merc850

    Mercury 85hp runs fine on Muffs but Boggs down in Sea

    Please don't rev it up to full throttle in the driveway, more that 2000 rpm's with no load can be destructive.
  10. merc850

    Mercury 402 40hp 1970s prop unit removal

    I'm afraid you are going to have to replace that LU because you have taken a piece out of the area where the exhaust goes into the prop. It will leak and cause cavitation and loss of speed.
  11. merc850

    Mercury 110 9.8 no-start

    That ignition relied on the points making contact to trigger the spark, if they are clean and set properly they should fire a plug. I don't have the gap setting info sorry.
  12. merc850

    Mercury 350 35hp stator

    I know where to find the parts - just look online. The points are set at .020" on the high side (lobe) of the cam.
  13. merc850

    MERCURY 200 20HP BASKET CASE QUESTIONS

    Here's the wiring diagram for the 75
  14. merc850

    Trim tilt pump

    The serial Nr. is at the top on that silver tag in pic 2. If your motor has the 4 hose cylinders you need a trim pump, all the fittings and the wiring harness - I wouldn't use just any hyd. pump the proper one has internal passages that allow the motor to kick up if you hit an underwater object.
  15. merc850

    What prop?

    A tach will help you get it right, the full throttle rpm range is 4800-5200, I would choose one that gives you 5200. A new tach can be hooked up to one of the yellow wires on the rectifier.
  16. merc850

    Missing serial and model numbers

    Look on the top of the block, a serial Nr. looks like [eg.] - "4085864". Yes a picture of the cowling will help.
  17. merc850

    Drain line on Mercury 7.5 hp motor

    Looks like an oil drain line that moves excess oil up to be burned/lubricate the upper bearing. The only way to get more water flow is to replace the impeller and make sure the water tube is clear.
  18. merc850

    No voltage regulator on older Mercury. Can I add one?

    Unregulated systems started in 1955 with the Mark 55 and were used up to the '80s and having been a boater for 50 yrs. I have never had a battery "boil over or spew acid" neither have the guys I boated with, the electrolyte would slowly go down over a season but no more than Granpa's old chevy...
  19. merc850

    Engine shutting off and bulb without pressure.

    Disconnect the fuel connector from the motor and pump the ball, if it gets hard and stays hard it's OK - if it pushes back into the tank the check valve is no good.
  20. merc850

    No voltage regulator on older Mercury. Can I add one?

    You can add a regulator to that system and then you can use a maintenance free battery, if you are using one now there is a possibility that the electrolyte will boil off - those systems were used with non-maintenance free batteries.
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