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Thread: 1978 20 hp mercury outboard need help

  1. 08-13-2018, 11:17 AM #1
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    Default 1978 20 hp mercury outboard need help


    I have been trying to get this old manual start motor going. Rebuilt the carburator yesterday and it started right up. I let it run for about 10 minutes in a barrel of water. Water pump working good also. Then all of a sudden it just went dead. No spark at all. I had already changed out coils with new ones. I checked kill switch and then I decided to check stator and trigger. Now is where I really think I messed up. When I started to pull the flywheel I removed all the 7/16 bolts on top of the flywheel not knowing that it would separate and leave the center piece still attached to the shaft. Well now I need to know did I really mess up by doing this and how will I know how to realign the flywheel. I did put it back together by bringing the #1 cylinder to top dead center and align the timing mark on 33° the best I could. What I need to know now is did I do the flywheel right? I just know just enough to get myself in more trouble seems like.
    Be safe and good luck fishing
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  2. 08-16-2018, 06:47 PM #2
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    ttt
    Be safe and good luck fishing
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  3. 08-16-2018, 08:32 PM #3
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    Look that thing over real close. I would think it would have some kind of alignment mark or offset boat hole or something to help put it back together. If I can find it I'm going to PM you a number to a guy I bet can help you.
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  4. 08-17-2018, 08:44 AM #4
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    Thanks Cray. I didn't know the flywheel was a 3 part unit until it was too late. Should have marked everything with a marker before I started doing anything. With all the other electrical problems with this motor I may just take it to a mechanic one day. This is just a extra motor I have, as my main fishing motor is still running.
    Be safe and good luck fishing
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  5. 08-17-2018, 11:27 AM #5
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    Can't help on the flywheel issue. But in my experience with no spark scenarios, it is almost always the powerpack/switchbox. If you find any documentation on checking that with a multimeter you may also run into an answer about the flywheel.
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  6. 08-22-2018, 08:38 PM #6
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    Turn the nut with the plugs out by hand, use a zip tie or something to see when the top cylinder is all the way up, flywheel should have timing marks with a TDC line on it, that line should line up with the timing pointer for proper placement of the flywheel
    Tom

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  7. 08-23-2018, 04:03 PM #7
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    Quote Originally Posted by Archerguy1 View Post
    Turn the nut with the plugs out by hand, use a zip tie or something to see when the top cylinder is all the way up, flywheel should have timing marks with a TDC line on it, that line should line up with the timing pointer for proper placement of the flywheel
    Thanks for the information.
    Be safe and good luck fishing
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