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  1. #1
    Member
    Join Date
    Jun 2020
    Location
    Jasper Texas
    Posts
    15

    1996 Mercury 200 EFI Ser# OG318597 Low power, random firing plugs

    Hello guys, back on here again with a problem. The motor ran great after our last fixes you helped with. New switch boxes, removed preignition system making it run super rich.

    Now after it sitting for 6 months from health problems, I take it out and it won't get on plane. Checked it out and saw that #6 cylinder wasn't firing or randomly, and #3 looked like it was firing at the wrong time. Pulled plug wires off while it was running and 6 and 3 made no difference in sound or rpms. Then restart it up later and it runs great on the water hose. This morning put it on the hose and started it 6 was firing but running rough. Checked voltage on outer switch box (red and white) was 57 AC volts. Blue and White wire was 126 AC volts @ 1000 rpms and went up to 167 volts when I raised the rpms up to about 3000. I see the manual says 180 volts minimum. Am I checking it correctly by putting my regular volt meter on it and checking to ground? Ohmed the trigger out and it came out to 1229 ohms +- 1 ohm. Zero ohms on all 6 trigger wires to ground. Trigger was changed out in 2014 (tag on it), didn't own boat then. Stator looks new and very clean. All wires look good.

    I had blueish garbage around the coils so I went ahead and put new ones on there along with new plug cables. All that looked like it was 25 years old. Lol.

    With those readings on the stator wires outer switch box, should I go ahead and get a new stator? Would this cause the random firing problem?

    Thank,
    Scott

  2. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
    Posts
    14,036
    #2
    got a built in direct voltage adapter in it capable of reading 400 or higher ???? test volts at coils running on green wires
    .................................................. ...the scariest thing in life is the unknown ...................................

  3. Member
    Join Date
    Jun 2020
    Location
    Jasper Texas
    Posts
    15
    #3
    No I dont have one. Will have to research what a DVA is. Probably will need one for the volts at the coils also right?



    Thanks Joe54, I know what I need now. My Volt meter I have now has it on DC but not AC. Will get back after I get one.
    Last edited by Wildride58; 04-14-2021 at 07:25 PM.

  4. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
    Posts
    14,036
    #4
    .................................................. ...the scariest thing in life is the unknown ...................................