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  1. #1
    Join Date
    Sep 2017
    Location
    So. Colorado
    Posts
    12

    Default 1971 Mercury 7.5 hp Model 751- Coils??

    I have a previous thread on this motor, but thought I would start another to slightly change the subject. This may be helpful to others. When I came in to possession of this motor, there was absolutely no spark. I have NO experience working on outboards, but do have a basic knowledge of mechanics, and how engines work. Went online to get as much info as I could find on this "OLD" motor. This lead me to replacing the insulators, which were cracked, and the wires that connect the points to the coils, as they were severely rotted. Whilst doing this work, I noticed that one of the coils was loose in its' housing. I removed both coils and noticed that on one coil the "ground wire" was on the same side as the connections and the two parts of the coil were not solidly connected together, while the other coil had the ground wire to the back side, both parts solidly connected. Both ground wires were laying on the outside of the rubber boot that cover the coils. Thinking I had coil problems also, I found information on the internet about testing coils. One, on youtube, showed a fellow testing with an ohmmeter and each of his readings at, or near, zero on the x1000 scale. I then found a site, I believe it was Fluke Instruments, that stated the resistance in the secondary coil should be upwards of 4k ohms!!!! All of my readings were at, or near, zero on each of my coils using the x1000 scale. Believing I had bad coils I searched for new ones. "Holy Cow"!!!! $130.00.......... each??? I did not want to invest this much money so decided to proceed with repairs and see what happened. Well, I got her all back together, and pulled the rope starter twice......"voila"...the motor started. I believe I still have some fuel problems, which should be easy enough to deal with. It is difficult to find information and parts for these old motors, and finding "correct" information seems even more difficult. Really looking forward to launching this 46 year old lady. Some measure of satisfaction in reviving her, also!!!

    Gary

  2. #2
    Join Date
    Sep 2017
    Location
    So. Colorado
    Posts
    12

    Default Re: 1971 Mercury 7.5 hp Model 751- Coils??

    The motor is a model 75!!! Cannot figure out how to edit the title. Sorry

    Gary

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