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  1. #1

    Default Help Identify Late 80's(?) 70hp Mercury 2 Stroke.

    Hi,
    Just purchased a 1990 17ft" Boston Whaler and having a hell of a time tracking down the model number or year of the 2 stroke 70hp Mercury it came with.

    Serial Number placard on the transom bracket is worn away. Can't find anything on a block plug or the flame arrestor cover. Took a look at NADA and doesn't look like Mercury made a 70hp 2 stroke in 1990-1993, so I'm assuming it's a 1986-1989. Possibly 70ELO or 70ELPO? Does anyone know by looking at it? Or another location I can look for a serial number?

    Grateful for any help, thanks in advance!

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    Last edited by analogjk; 01-01-2020 at 12:59 AM.

  2. #2

    Default Re: Help Identify Late 80's(?) 70hp Mercury 2 Stroke.

    Some More Photos:
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    I see "M 70" in the above photo - and do see some references online, but not an actual Mercury model number.
    Last edited by analogjk; 01-01-2020 at 02:10 AM.

  3. #3
    Join Date
    Sep 2010
    Posts
    18,179

    Default Re: Help Identify Late 80's(?) 70hp Mercury 2 Stroke.

    They only MARKETED that engine as a 70 HP in 87 / 88 / 89.------Other years as a 75 / 80 / 90 HP model.------Parts are generally all the same.------Install a new water pump impeller and test oil injection output before launching the boat.

  4. #4

    Default Re: Help Identify Late 80's(?) 70hp Mercury 2 Stroke.

    Quote Originally Posted by racerone View Post
    They only MARKETED that engine as a 70 HP in 87 / 88 / 89.------Other years as a 75 / 80 / 90 HP model.------Parts are generally all the same.------Install a new water pump impeller and test oil injection output before launching the boat.
    Much appreciated and I’ll definitely take your advice. Ordering a service manual today - happen to know the procedure to test oil injection for each of the cylinders?

  5. #5
    Join Date
    Sep 2010
    Posts
    18,179

    Default Re: Help Identify Late 80's(?) 70hp Mercury 2 Stroke.

    Oil is injected into the fuel BEFORE the carburetors.-----You basically hook up a 50:1 fuel supply.----Then run the motor and measure the volume of oil pumped over 10 minutes.----A factory manual outlines how you do this.

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