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is my stator bad? or do i have another problem?

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  • is my stator bad? or do i have another problem?

    i have a 1995 Baja Jetboat 90hp mercury motor.

    the boat will startup fine, and then after about 3-5minutes will die in idle and we cannot restart it. The motor turns, fuel pumps, and we see spark on the plugs, but the engine will not fire. Also all the plugs are tyically wet at this time as well. From doing alot of reading i'm starting to think it is the stator that is bad. I've already read about the switchbox going bad. I have a multimeter and called CDI Electronics today and we run a ohm test on the red and blue wires. the blue came back at 3280 and black at 69/70.

    the CDI tech told me the ohm test is totally unreliable and only a DVA test wouuld prove with 100% accuracy. He said if i were to guess and trouble shoot that it is likely the stator.

    I also called mercury marine who thought the problem was the fuel pump.

    I called the local boat mechanic who thought it was a cracked coil (due to the boat shutting off after warming up).

    I should also mention the idle seems alittle rough and irratic.

    we have new gas in, checked all carbs (look good), new plugs, new wires. We even had the boat running down the river or 10 minutes at full throttle(very slow felt like 1/2 power...but this is a new boat and no clue how fast it should go if running correctly).

    Technically the red wire test on the stator failed so is it the stator? I really want to order parts asap and get the boat up and running. the local boat mechanic is expensive and said it will be 2 weeks before he can even LOOK at the boat. Any other tests i can run? Any questions i can answer? My brother , who is helping me to fix the problem, is a 10yr diesel mechanic (not marine), i am just a guy with little mechanical skill who wants to get this fixed

    one last thing i should mention is that we did have a problem with the carb when i first bought the boat (as full of varnish and had a stuck float) we didnt know it at the time (before we rebuilt the carbs) and sprayed a bunch of ether into the carb...which actually started the boat and the idle became extremely high, the boat was started out of water, we pulled the key, pulled the kill switch, unplugged the spark plug wires, and the motor was still running! It ran at full throttle like this for a good 2-3 minutes before we had enough common sense to both pinch the fuel line and try to suffocate the air intake, which did stop the motor finally. My fear is that this excess heat caused some damage to something in the electrical system, but again i'm NOT a mechanic and the problem could be totally unrelated before i spend $200 on a stator. The motor appears to have decent compression and no other unusual mechanical problems appear apparent.

  • #2
    Re: is my stator bad? or do i have another problem?

    anything else i should add? i really want to diagnose this better or buy the correct parts asap.


    • #3
      Re: is my stator bad? or do i have another problem?

      Take it to somebody with a little experience and common sense, and pray you haven't totally wrecked it yet.


      • #4
        Re: is my stator bad? or do i have another problem?

        uh no, thats why i'm asking here.


        • #5
          Re: is my stator bad? or do i have another problem?

          I'm amazed that the engine ran away that bad, especially with no cooling, and survived. Have you actually measured compression, or are you guessing? The symptoms you describe are usually caused by low compression. (Got gas, spark, and no fire) Are you guessing on the spark or have you checked it out with a spark gap of 7/16".

          Speaking of guessing, the way to diagnose the ignition system is to check stator output, coil drive, etc. with a DVA. Anything else is guessing. It is, on average, less expensive to acquire the needed test equipment and properly diagnose the problem to a single part than throwing parts at it till it's fixed.

          hope it helps


          • #6
            Re: is my stator bad? or do i have another problem?

            compression 120 120 135


            • #7
              Re: is my stator bad? or do i have another problem?

              we just tested the compression and pulled off the flywheel almost have stator out. should we see visible damage (melting) to the stator?


              • #8
                Re: is my stator bad? or do i have another problem?

                stator out, we see no visible damage. stator reads on my multimeter 71 ohms at blue 3280 on red on brothers more professional meter 104 ohms blue 3340

                according to CDI should read between 70-90 on blue and 3250-3650 on red


                • #9
                  Re: is my stator bad? or do i have another problem?

                  Compression is uneven enough to be a concern. Variation from specification that is uniform and proportional is usually a meter out of calibration, not the stator.

                  You obviously aren't (listening). The proper diagnostics don't require major disassembly, but they do require the right meter and instructions.

                  You keep guessing. I'm outa here


                  • #10
                    Re: is my stator bad? or do i have another problem?

                    then tell me what else to do do diagnose the problem. I am NOT going to buy a DVA meter, if it were available at local hardware store i'd pick one up immediatly. I'm also NOT going to wait a month for the dealer to diagnose my boat when i'm more than capable (minus a DVA). What else should be tested next and what specifically does the variance in compression point towards?

                    also anything above 120psi means no damage. from what i've read 135 is compression at factory. 120 is typically a used motor. Unusure why the lack of uniformity


                    • #11
                      Re: is my stator bad? or do i have another problem?

                      just called mercury marine and they said the numbers although high are still within range. He also asked if the bottom cylinder read the 135 which i said yes to. he said that is what he expected since the bottom cylinder typically reads higher. Anything higher than a 10% deviance is a problem and although we are right at that mark he said it is still within range and he would assume the motor is just fine. Also lower than 100lbs would indicate a problem or greater than a 10% difference. (typically GREATER than (not equal to) 15 points higher)


                      • #12
                        Re: is my stator bad? or do i have another problem?

                        Lack of uniformity is probably due to your motor running away without any cooling water. It's not great, but other than maybe a slightly rough idle, you shouldn't have any major concerns with a 15 psi difference. It is about a 12% difference between them, we like to see <10, but you should be ok. Order a DVA meter online, if you want to save money by only ordering the parts you need, you obviously have internet service. I did my ignition system on a 115 inline 6 without using a dva, HOWEVER, i was planning or replacing EVERYTHING anyway because the wiring was shot and becoming a fire hazard. So you have two choices, throw money at the motor by guessing and getting parts to throw on to see if it helps, or spend money on a tool to diagnose exactly what part is wrong, it's up to you. Also, NEVER, and i mean NEVER NEVER NEVER start a 2 stroke outboard with Ether or any other starting fluid! This is probably another reason for your uneven compression numbers. Ether does not contain any lubricant and actually washes the lubricant off of the cylinder walls! It's bad ju-ju.

                        EDIT: oh btw, the main problem is the motor is on a Baja!
                        Just messin with ya man. Checkmate Forever.


                        • #13
                          Re: is my stator bad? or do i have another problem?

                          J was trying to tell you, the most expensive way to repair a motor is to ASSUME the stator is bad and start replacing parts. This get VERY expensive.

                          A DVA adaptor isn't expensive, you can build one quite cheaply.

                          DVA testing is THE only reliable method of determining which ignition component is at fault, IF a spark test shows a fault.

                          The ignition MUST BE capable of generating a 7/16 inch spark in free air, any less and the motor will not fire under compression. Without a valid spark test you have NO IDEA if, or what your problem is, other than an inability for follow good advise.

                          Also, minimum cranking speed is 300 RPM, and less and the ignition will not function. Battery, cable connections, starter, any/all can seem to be fine and your motor still will not start.

                          Learn to accept solid advise from people that have forgotten more than you may ever know.


                          • #14
                            Re: is my stator bad? or do i have another problem?

                            "you can build one quite cheaply" my brother and i are extremely proactive, is there a thread somewhere where i can read how to build my own? Also i got impatient and ordered a new stator.

                            and yes believe me we learned our less about ether and starting the boat out of water. You have to realize we never owned a boat before and my brother has 10+ years as a desile mechanic, obviously 2 stroke marine engines are a different animal. Hopefully i guessed right on this being the stator (or switchbox...yikes). The stator appears to have zero external damage (no clue internally, but it did FAIL the ohm test).

                            Again if you know how to build the adaptor i will follow suit and do so and report our readings

                            found it, but no instructions on how to build it for dummies


                            • #15
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                              Re: is my stator bad? or do i have another problem?

                              hey i was in your shoes a few years ago when i got my first boat. I took a look at the outboard and electronics and went "oh boy, what did i get myself into." Understand i have always done work on cars and trucks (have multiple engine swaps under my belt), but these are different beasts. But i got a repair manual and got to it. All it is to me now is a multiple cylinder chainsaw. I see you have chosen the potentially expensive route of "hoping", and i sincerely hope you are correct and the stator is the problem. However, this could very easily be a switchbox problem as well.