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'89 Mariner 175 No hole shot power

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  • '89 Mariner 175 No hole shot power

    Motor starts up just fine. Seems to idle just fine. Really boggy on hole shot and takes a good bit to get on plane. Once on plane though, it runs pretty good. Probably running a little low on RPMs at WOT. This issue has gotten worse over time. I'd say about 4-5 years. So I don't think it's a prop issue. It used to jump out of the hole pretty good.

    I just went through the carbs and replaced needles and seats. All floats calibrated and functioning. New fuel filter late last summer.

    Where's a good place to start trouble shooting? Electrical, fuel, timing or ????. Could it just be compression? (I need to test this asap but need to get a tester first.)

  • #2
    Check the compression, go rent a tester at autozone, orielys ETC, or buy one. That's usually the first place I always start.

    Compression, then spark, then fuel.

    As long as all the cylinders are pretty even, you can safetly mark that off the list, I believe it's 15%, but I like to see within 1-5PSI of each other, but that's just me.
    Spark is another possibility, a weak spark would cause issues like you are describing.

    Unless you've chewed your prop up a LOT, or it's slipping on the rubber hub, I wouldn't be looking at the prop.


    • #3
      Thank you for the response. Compression test is first on the list of to-dos. Just curious, if compression tests out ok, what parts could I be looking at in terms of spark issues? Coils and wires? Or switch boxes and rectifiers? Or all of the above? Thanks again!!


      • #4
        If compression tests out, then I would pull all 6 plugs out, ground them to the block, and have someone crank the engine and watch for good spark on all 6 plugs: Alternatively you can get a spark plug tester for under $10 at any autoparts store, and check each plug plug with that tool. If there is no spark, weak looking spark, or only spark on certain cylinders we can start addressing that. If it comes to that, it could be stators, triggers, coils, switch boxes ETC.


        • #5
          Hello - I got a chance to get a compression tester on the motor but I'm afraid I didn't get accurate enough readings. The test I borrowed from Oreilys didn't have a long neck screw in for the plug hole so I don't think I was able to seal them up well enough. Regardless I tested them all anyway. They all were topping out at about 90. I feel like that's low and I've heard numbers like 110 or 120. Then again I wasn't getting a solid seal on the tester either. So either they're all pretty even or because of the tester not being sealed they were just showing to be mostly even. I'm going to find a different tester and try again.

          I did have another question though that's carb related. I feel that I should get a carb sync tool on this motor to check that. Where exactly do I hook up the vacuum lines for a sync tester on this motor? Thx again for any help.


          • #6
            All gauges read differently, if theyre even thats the most important thing, however get the correct gauge and fitting and check that just to be positive. As for the Carb Synch, I'm not aware of a tool to do that, there's a procedure in the manual for a "link and synch" However, if it used to run fine, I wouldn't think that would be the cause of the issues you're experiencing. The way I always "checked" them, was make sure they're all opening all the way together, and closing completely together. Should be able to pull the airbox off the front of the carbs and move the throttle cam on the side of the carbs and see if they're opening and closing in the same manner. Wouldn't hurt to clean the carbs if you haven't done that..... Run that compression test on it, and then check your spark, if those two things check out we can move to the fuel system Carbs, linkages primer bulb, fuel lines things like that. Get the easy stuff out of the way first.


            • #7
              Did you do a link and sync as per your service manual after putting your carbs back on? My 175 black max wouldn't get out of the hole, did a link and sync and problem solved.


              • #8
                I have only owned this boat for 1 month and only been in the water twice.

                I agree with above posts, fuel, spark, carbs, bulb etc first.

                i too am having those issues on an 86 mariner magnum 150hp, ran really rough in the lower RPM and stalled out a bunch. Some guy said to rebuild the carbs.

                I ended up buying a carb cleaner tuner from johnson. Spray it in the carbs while running. Also put concentrated yamalube ring free in a small tank and ran that.

                I had another mechanic check the stator and he said the stator is testing outside the normal range. and that the stator would give me those problems of low rpm irregular acceleration. We have ordered a stator replacement anyway.

                I took the boat out for a water test on the weekend and after the carb cleaning I did and it runs very well. No stalling at low idle or low gear. no stalling in reverse.

                I actually was able to get the boat up to 80km/h or 50mph.

                I did find it a little tough to get up on plane, not sure if that is an issue or not.

                I will still change the stator as the mechanic said it tested outside the operating range and the stator can give me the issues i was experiences.

                One other thing that might be the problem and you may want to consider if your only complaint is the slow to plane. Could the boat be absorbing water in the back? Is there excess weight in the back part of the boat b/c of a leaking motor bolt holes or anything else? The reason I say this is that I took out the batteries and the inside deck was full of screw holes through the fiberglass. I also suspect a motor bolt is leaking into the boat. I need another water test to confirm and may do that before too long.

                Best of luck


                • #9
                  Originally posted by 444 View Post
                  Did you do a link and sync as per your service manual after putting your carbs back on? My 175 black max wouldn't get out of the hole, did a link and sync and problem solved.

                  This is refreshing to hear. No I didn't yet. Thanks for the insight.


                  • #10
                    A little update. Through a friend I got a tech to check out my motor. He had a proper compression tester. All cylinders were right around 125. whew, happy for that. Spark checked out perfect. I think he said it was jumping like a 1/4 inch on his tester. He also brought a probe camera and checked all of the cylinders visually.

                    In the end, he seems to think that it's likely a buildup of carbon that is robbing the power. So he suggested getting a can of Power Tune and following the directions. I'm planning to do that tomorrow night. Spray into carbs until it dies, also spray into plug holes and then let it sit overnight before starting back up to flush it out.

                    He seemed to think it was not a timing issue or anything to do with electrical components. Just purely mechanical. Any thoughts on the above? I wasn't thinking it could be something so simple but maybe that's all it is. I have been using it much less the last 3-4 years (kid #2 and a job relocate are the cause of that).


                    • #11
                      you mentioned you changed the spark plugs and the fuel filter. The pump bulb is good and there isnt any debris in the gas tanks that would clog the fuel line.
                      So that is where we are starting.

                      I also suggest you start putting the stabilizer into the gas every fill up.

                      I cant believe how bad my engine was. stall outs in idle or low gear, really rough on low speed. Stall out in reverse.

                      The thing runs great now. I had guys telling me I have to rebuild the carbs.

                      I had my stator checked and it check outside of normal so I changed it anyway.

                      Like one guy said, its a $20 can of carb cleaner, or yamalube ring free. Start there and see what happens.

                      I wonder how often you should run the carb cleaner?

                      I also put a full can of ring free into a 1/3 gas tank .


                      • #12


                        • #13
                          engage tha enrichner when it acts up... if it improves then its a fuel delivery deal.. lines, pump, primer bulb, float settings all could be suspect......


                          • #14
                            Gee, a decarbon treatment is not going to fix your issue, IMHO.
                            Those motors have low and high speed stator windings. Since you were able to achieve high speed operation, it is likely the ign system is good.

                            Some of those older V6 carbs had no adjustments for low speed fuel mixture. The carbs must be spotless to maintain correct mixture. Low speed Mixture is very important to allow proper hole shot. Hopefully your carbs are spotless.

                            I would check the link and synch next. I would expect 0-9* ATDC for idle pickup timing and 21* BTDC for max spark advance.


                            • #15
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                              Chris - If the link and sync has never been touched would it make sense that it would need to be checked? Could the motor get out of time, over time and usage?

                              Would a bad stator still produce good spark when turning over the motor but not have good spark or the "right"(?) spark when up and running and trying to run the boat?