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  1. #1
    Member
    Join Date
    Dec 2022
    Location
    Ohio
    Posts
    3

    80s Model Johnson Gt150

    New to the forum..

    Bought an 82 Starcraft Islander V5 with a Johnson GT150 2 stroke that needed some TLC this summer. It's my first boat, and I got everything "working" (or good enough) and took it out a few times. Now that it's off season and I have some time to do some tune up there are two main issues that I need to address and need some pointers as I have limited knowledge on this motor. I know the year is between 80-88, and the compression is decent on all 6 (98-90).

    1.) The first issue is the motor acts like it doesn't pull fuel consistently. When I first got everything working, it would start up second crank almost every time with only using the key-in choke. The gas and oil primer bulb would get firm. As the season went on and I had taken it out a few times, it began to take much longer (10-15 minutes of cranking) to get the motor to fire up. The oil primer bulb is always firm but the gas primer bulb will never get firm at all now. When starting, I will prime the bulb 3-5 times, crank 5 or 6 times and it will act like it wants to start. It'll run for just a second but act like it's lacking the fuel to keep running. I'll use the key in choke and the choke lever all over the place, but it doesn't seem to matter. Eventually it will always start up, just takes a lot of play. I've replaced all the fuel lines going into the motor and the primer bulb, but no difference. It seems like it will get close after priming, but after 5 or 6 cranks, all the gas I pumped into motor will be sucked out and I have to prime again as the bulb will be completely empty. I'm afraid of too much priming or draining my batteries from all the cranking. What could be causing no pressure in the bulb or such an inconsistent fuel pull? Once it starts running, it will run fine as long as I dont let it idle for very long with no choke at all. Not sure if this is related but after starting, I'll make my run and it will be fine. But if I leave the motor idling with no gas or choke, it will die after about 45 seconds.

    2.) The tilt trim I have is in rough shape. When I first got it, I knew the tilt trim had a very slow leak, but the nut that it was leaking from is completely inaccessible unless you take the motor off, I've tried every redneck trick I know. Which I was fine with and just always kept tilt trim fluid with me. But on my last trip, got the boat on the trailer and the motor would not raise. After 5 minutes of frustration, I was able to tap the motor with a wrench while lifting up on the motor and eventually it raised (no problems trimming the motor down). When I would try to raise the motor, all I would hear is a clicking in the main fuse box with a contactor. I checked the relays, and they are fine, so I'm 95% sure its the tilt trim motor going bad. The boat did come with a 'spare' tilt trim. It's definitely used, I'm not sure if it's good or not. My question is, could I test the spare tilt trim I have before I switch them? I know I can, Im just not sure how accurate a test will be, seeing as it doesn't have the weight of the motor on it. I just kind of hate to go through all that work to put a tilt trim on that doesn't work.

    I know it's a can of worms, but any guidance at all would be a huge help. I love to fish and be out on the water, but being a first year teacher with student loan payments, my budget is limited. I'm pretty handy and it would be much more practical for me to fix these myself instead of taking it somewhere and paying for labor. Even if its just making it work instead of working like it should lol. Appreciate it!

  2. Member
    Join Date
    Apr 2014
    Location
    SW, Ohio
    Posts
    17,205
    #2
    not sure where you are in Ohio but a few of the gurus on here are in SW Ohio and know these older motors well
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  3. Member
    Join Date
    Aug 2011
    Location
    Erie
    Posts
    2,382
    #3
    You first problem sounds like my '88 Johnson 50 hp VRO engine. It's a S L O W build up of blocked fuel lines and carburetor from ethanol fuel. I put up with it for the last few years I owned it but once started for the first time that fishing day it ran very well. I would suggest replace ALL fuel lines, bulb and a good carb cleaning and don't forget the small fuel filter if it's like my 50 hp.

    On your second problem mine was just a internal leak in the Trim n Tilt system. It didn't lose any fluid but the engine would slowly come down on it's own. My dealer told way back the that no parts are available to rebuild it. Not sure if that was true or not so I just put up with it.

  4. Member
    Join Date
    Dec 2022
    Location
    Ohio
    Posts
    3
    #4
    Thanks Fireball. My plan is to start by tackling problem 1 first. I have replaced everything (lines, filter, and bulb) going into the motor. My next step will be to replace all fuel lines inside motor and cleaning all the carbs and seeing if that has any effect. Not as concerned with problem 2, just because I know I can make it work. Will update when finished.

  5. SC Club Moderator ChampioNman's Avatar
    Join Date
    May 2004
    Location
    Crawfordville, FL/Lake Hartwell, SC
    Posts
    71,248
    #5
    Install new carb kits when you tear them down, don't tear down, clean and reassemble.