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  1. merc850

    Merc 900 90HP ignition wiring help

    That's a point ignition ( 2 sets of points are under the cap); the red terminal cap must be removed first if you are checking the cap! It looks like you have a different control box than the original if all those wires in the 1st photo are from it. Here's a diagram that should match the engine...
  2. merc850

    Old Merc Model 200 tiller 20hp

    "Full handel had broke off" if you're talking about the tiller handle it's possible that it's not set up correctly and instead of "START" the spark is advanced to "RUN" which would be too far advanced for starting; see if this image helps.
  3. merc850

    Mercury outboard 140 spark issues

    The serial Nr. should be on the plate between the clamps. The blue switch is to cut off the ignition if the motor is knocked out of the water. I've found the serial range 3293234 thru 3502805.
  4. merc850

    Mercury outboard 140 spark issues

    Have you looked in the dist. cap maybe the rotor is cracked or the contacts are corroded; there's a timing belt under the flywheel and it turns the distributor, when you take the cap off see if you can turn the rotor gently - if it turns around the belt is ruined. Fig. 3 shows the belt and dist...
  5. merc850

    1957 silent 6 model 1056344

    This is from the 1965 and prior manual, the co-pilot locking ring might be accessible by tilting the motor up.
  6. merc850

    '76 Merc 85hp Wiring from Engine to Control Box Help

    Right from the manual; if yours is really a 1976.
  7. merc850

    Surface gap versus standard sparkplugs

    A little history on surface gap plugs
  8. merc850

    1977 1150 lose power when at load

    OK, the only thing that is not new is the trigger in the distributor? A failing trigger will work sometimes then not; do you have spark now? You can test the trigger by following these steps: The vent orifice is for the back drag carb fuel economy circuit it reduces the atmospheric pressure at...
  9. merc850

    85hp Mercury Trim Pump Nightmare

    Does the motor turn over? If so but the rams don't move then you should bleed the system; if not then check the brushes in the end cap; there's also a circuit breaker in the end cap that might be dirty - you can clean it with fine sandpaper
  10. merc850

    1973 Mercury 850 Thunderbolt issues

    I had the same problem but it was the trigger that was going, before you throw money away use these steps to trouble shoot. CDI sells the trigger and switchbox.
  11. merc850

    Mercury 65 HP 4 Cylinder Wiring Diagram

    After you clean the carbs and check the fuel pump you should check the magneto; if you're serious about this motor a manual is a must.
  12. merc850

    Mercury 65 HP 4 Cylinder Wiring Diagram

    If you haven't found a wiring diagram here it is
  13. merc850

    Forward and reverse

    It's possible that the upper shift shaft has twisted especially if is on a motor that has been sitting in salty or highly acidic water for 40+ years. This happened to me it will go F - N but because it's twisted there isn't enough travel to reach R. I bought another motor with a perfect shaft...
  14. merc850

    Mercontrol problems 85 hp model 850

    If the pump motor is working then maybe you should bleed the system
  15. merc850

    Buying 1970’s Mercury power trim?

    You need the switches/wiring harness, the cables for power from the battery, 4 hoses,rubber bushings for the shock mounts and you remove the reverse lock cams from the LU. You will also have to bleed the system. One thing that can happen is the motor brushes wear down so the motor won't work...
  16. merc850

    More 1977 850 Merc problems

    If it really is a 1977 this wiring diagram is it, the rectifier only charges the battery the ignition is fired by the stator/trigger assembly and this requires the motor to turn over quickly; you can even run it with the harness disconnected. I would check the ground wires at the switchbox and...
  17. merc850

    Mercury 500 water pump replacement questions the

    The long piece goes into the outlet - taper facing up, the round piece looks like the slinger which goes on the driveshaft after the pump is assembled. Push it down until it's just above the pump housing but not touching. You'll also need the long plastic piece that guides the water line into...
  18. merc850

    replaced water pump problem..I think

    Here's a cut thru showing the internals; the exhaust goes down the tube to the prop and water surrounds it.
  19. merc850

    Possible new trim pump?

    If it's the older system with the pump inside the boat you have to bleed the system if it has the pump and rams between the clamp bracket you cycle it a few times.
  20. merc850

    80s mercury classic 50 overcharging

    I put a regulator in my motor last year, the regulator is a Mercury one that I had lying around and I bolted it to the front cowl support (I think it should be grounded). This gives me 13.5 v constantly.
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