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  1. #1

    Default 40hp 4 stroke starting issues

    I inherited a older boat with a newer engine , mercury 40hp 4 stroke, year 2000. It has been out of use for years. My brother said it has less than 40 hours on it. last year I used it once and it never seemed to run smooth. it did start every attempt. I disconnected the fuel line between bulb and tank and discovered lines were plugged with varnish. So I cleaned tank and filter, replaced lines, fuel filter. verified fuel gets to filter with no problem. disconnected fuel line marked OUT at fuel pump and cranked motor, gas came out. And that is where im at. Any ideas what to do next? hoping to mess with it this weekend. Thanks

  2. #2
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: 40hp 4 stroke starting issues

    You can try using seafoam in the carb. Get a can of seafoam and start the motor and run it out of fuel. Then put the fuel line in the can of seafoam and pump the carb full of seafoam and start it for a couple seconds and then let it sit overnight. Connect it to the fuel tank and start it the next day and run it until it stops smoking. That should dissolve all the varnish in the carb and just burn it up. Be sure and run the engine out of fuel between uses and keep the fuel tank topped off after each use. If that dont work you will have to rebuild the carb and possibly the fuel pump.

  3. #3

    Default Re: 40hp 4 stroke starting issues

    Quote Originally Posted by kimcrwbr1 View Post
    You can try using seafoam in the carb. Get a can of seafoam and start the motor and run it out of fuel. Then put the fuel line in the can of seafoam and pump the carb full of seafoam and start it for a couple seconds and then let it sit overnight. Connect it to the fuel tank and start it the next day and run it until it stops smoking. That should dissolve all the varnish in the carb and just burn it up. Be sure and run the engine out of fuel between uses and keep the fuel tank topped off after each use. If that dont work you will have to rebuild the carb and possibly the fuel pump.

    Thanks for input!I will try this.

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