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1977 Johnson 75HP Bad Pack, Stator, or Timer Base

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  • 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

    Hello all,

    Thanks in advance for any help or advice I may receive for my problem.

    Motor: 75ELR77S
    I have a Seloc manual that covers this motor.

    Compression is as follows:
    130
    125
    120

    Items I have replaced:

    Water pump
    Fuel pump
    fuel lines (from tank to carbs)
    rebuilt carb's...completely including carb kits.
    Installed Tell-Tale on block.
    New oil in lower unit.
    Spark Plugs
    Starter soleniod

    I just purchased this motor to fix and put on my bass boat. I had this motor running before the carb rebuild, but in the water it would die if put in gear. Forward could sometimes be eased up in RPM's before it would die out, but reverse would die immediatly.

    After rebuilding carbs, exact same problem, it would die in gear. Both before and after, it would idle great and RPMs could be increased with the warm up lever. So, I decided to do a decarb just for &^%'s and giggles. Ran a product my boat shop recommended (made by teleflex?) through the carbs, let it sit, and during the run period after letting it soak, after about 5 minutes the RPM's jumped slightly and had a very smooth idle for about 4 seconds then died. Now it has no spark.

    I have eliminated the key switch by disconnecting the appropriate wire from the power pack. I disconnected the rectifier, but still no spark. My manual says I need a neon tester to check the stator and power pack, but I can't seem to find one. I tried taking a few measurements with my multi-meter, but the manual is a little hard to follow. If I did it correctly, my stator resistance is about 6 ohms throughout. I can't seem to get the 150 volt reading that I found on the internet. In fact, I can't find any high voltage readings while cranking.

    My question is this, should I replace the power pack, stator, or timer base first? Money is tight this day and age, and my wife is about to make me live in "that stupid boat"...

    Thanks again for any input.


  • #2
    Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

    First, check coils for insulation cracks. Then, check primary and secondary coil winding resistances. If that's ok it could be the power pack or the stator. I have a neon testor, bought it during my racing years 1977-1985, and they weren't cheap. Best to go to a JohnRude dealer who was active in that era and let him test the powerpack. I've had both powerpack and stator fail on a 1975 75. By the way, the compression's low, 150 psi is very good but 130 is not. Motor will run ok but you won't get top acceleration from it. That hurts, because the 75 (as opposed to the 70) was built as a racing motor with port timing built for high RPM. 6500 RPM (with 50% more oil) is moderate for that motor. Use a prop that lets the motor turn at least 6000 RPM.




    Originally posted by DoubleBarS View Post
    Hello all,

    Thanks in advance for any help or advice I may receive for my problem.

    Motor: 75ELR77S
    I have a Seloc manual that covers this motor.

    Compression is as follows:
    130
    125
    120

    Items I have replaced:

    Water pump
    Fuel pump
    fuel lines (from tank to carbs)
    rebuilt carb's...completely including carb kits.
    Installed Tell-Tale on block.
    New oil in lower unit.
    Spark Plugs
    Starter soleniod

    I just purchased this motor to fix and put on my bass boat. I had this motor running before the carb rebuild, but in the water it would die if put in gear. Forward could sometimes be eased up in RPM's before it would die out, but reverse would die immediatly.

    After rebuilding carbs, exact same problem, it would die in gear. Both before and after, it would idle great and RPMs could be increased with the warm up lever. So, I decided to do a decarb just for &^%'s and giggles. Ran a product my boat shop recommended (made by teleflex?) through the carbs, let it sit, and during the run period after letting it soak, after about 5 minutes the RPM's jumped slightly and had a very smooth idle for about 4 seconds then died. Now it has no spark.

    I have eliminated the key switch by disconnecting the appropriate wire from the power pack. I disconnected the rectifier, but still no spark. My manual says I need a neon tester to check the stator and power pack, but I can't seem to find one. I tried taking a few measurements with my multi-meter, but the manual is a little hard to follow. If I did it correctly, my stator resistance is about 6 ohms throughout. I can't seem to get the 150 volt reading that I found on the internet. In fact, I can't find any high voltage readings while cranking.

    My question is this, should I replace the power pack, stator, or timer base first? Money is tight this day and age, and my wife is about to make me live in "that stupid boat"...

    Thanks again for any input.

    Comment



    • #3
      Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

      look here http://www.******************/page29.asp
      FLORIDA GATORS
      TEBOW Country



      Please, NO PM's (Private Messages) regarding boat/engine problems. they will not be answered.
      That is what these forums are for. Post your questions, in the appropriate Forum.

      Comment



      • #4
        Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

        Originally posted by tashasdaddy View Post
        Thanks for the link. I found that same page yesterday, but the problem I ran in to is it says check stator resistance from the brown wire to the brown/yellow, but I don't have a brown/yellow wire.

        My wires are as follows:

        to the power pack from the timer base:

        3 white/black
        1 black/white

        to the terminal block from the stator:

        yellow
        yellow/gray
        brown
        brown/orange

        Should I be checking resistance from the brown to brown/orange?

        Thanks,

        Cory

        Comment



        • #5
          Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

          Ok, I went back to the drawing board. Using the info found on the link tashasdaddy provided, here is what I have found (swapping Brown/Yellow for Brown/Orange):

          Stator resistance (brown to brown/orange): 672 OHMs
          DVA output from stator (Brown to Brown/Orange): 3.8VAC
          Timer Bases resistance(black/white to all white/black): 8.7 OHMS, 8.7 OHMS, 8.6 OHMS
          DVA output from timer base(same as above): .08 VAC, .08 VAC, .12 VAC (DC was 0,0,.2)
          DVA output from black/white to ground: 1.2VAC (DC was 1.5)
          Disconnect trigger wires retest: .4VAC

          I visually checked the ignition coils, but they appear to be fine. I know that doesn't mean much, but they are not cracked.

          Thanks again.

          Comment



          • #6
            Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

            Well, I talked to my boat shop (over an hour away), and told him the situation. He said he would put money on the power pack. I went ahead and ordered it, so we will see if I end up with a $130 dollar paper weight. I'll keep you posted if it fixes the problem.

            By the way Sandhammaren05, what did you mean by 50% more oil. Should I be running a higher gas/oil ratio? I run 50:1, should I run something different for this motor?

            Comment



            • #7
              Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

              your compression is fine, you are running 50:1 which is correct.
              FLORIDA GATORS
              TEBOW Country



              Please, NO PM's (Private Messages) regarding boat/engine problems. they will not be answered.
              That is what these forums are for. Post your questions, in the appropriate Forum.

              Comment



              • #8
                Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                I think power paks are like VRO's. Everybody. gets one wether they need it or not. I would like to have all those burned out pak's

                Comment



                • #9
                  Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                  6000-6500 RPM 50% more oil.
                  over 6500 RPM double oil.
                  alternative: use E-tec XD-100 oil at 50:1 at
                  any RPM. Powerpacks are cheaper on Ebay if
                  you can find one for your model ... .



                  Originally posted by DoubleBarS View Post
                  Well, I talked to my boat shop (over an hour away), and told him the situation. He said he would put money on the power pack. I went ahead and ordered it, so we will see if I end up with a $130 dollar paper weight. I'll keep you posted if it fixes the problem.

                  By the way Sandhammaren05, what did you mean by 50% more oil. Should I be running a higher gas/oil ratio? I run 50:1, should I run something different for this motor?

                  Comment



                  • #10
                    Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                    Wrong. No one knows 75s better than I do, including the mfr. (now defunct).


                    Originally posted by tashasdaddy View Post
                    your compression is fine, you are running 50:1 which is correct.

                    Comment



                    • #11
                      Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                      Originally posted by tashasdaddy View Post
                      your compression is fine, you are running 50:1 which is correct.
                      Exactly.

                      The 75 was not designed to be a racing motor, though it made a good one correctly modified. The problem is that if you treat it like a racing motor it will be temperemental as all get out.

                      Your SELOC manual probably has you misguided on the link 'n' synch. Get an OEM Manual.

                      On your ignition problem. What do you suppose the odds are that three coils that were working fine a minute ago ALL fail at once? There is room for some logical thinking here.

                      Sandy probably know a lot about the 75 as a racing outboard. That does not make him more expert than the guys who designed it. He surely is no expert in dealing courteously with other JohnnyRude experts.
                      sigpic

                      Comment



                      • #12
                        Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                        Wrong again. The 70 was designed for normal use, the 75 powerhead was designed only as racing motor, the port timing is completely different than on the 70, and the standard compression is 140-155 psi insterad of 120-130 psi (the 70 has a thicker head). No modification whatsoever was necessary for racing (the shortshaft is the racing model, and the longshaft powerhead is exactly the same), and in both APBA and NOA no modification was permitted. the motor turned 6000-7000 RPM on pad-V-bottoms, and 7000-8000 RPM on tunnels. Double oil over 6500 RPM or pay the price.



                        Originally posted by JB View Post
                        Exactly.

                        The 75 was not designed to be a racing motor, though it made a good one correctly modified. The problem is that if you treat it like a racing motor it will be temperemental as all get out.

                        Your SELOC manual probably has you misguided on the link 'n' synch. Get an OEM Manual.

                        On your ignition problem. What do you suppose the odds are that three coils that were working fine a minute ago ALL fail at once? There is room for some logical thinking here.

                        Sandy probably know a lot about the 75 as a racing outboard. That does not make him more expert than the guys who designed it. He surely is no expert in dealing courteously with other JohnnyRude experts.

                        Comment



                        • #13
                          Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                          Easy folks, I didn't mean to start a fight. I was just looking for some input on my problem. Like everyone here, I don't want to spend money on parts that I don't need, so that's why I came to you folks.

                          Whether it is a racing motor or not, it is not setting any speed records while it is sitting in my shop, and if I ever get it running, it won't be used for racing in my situation. It's just going on a 16' tri-hull bass boat to go to and from fishing holes. What ever is decided in the end, I will run the required oil to gas ratio. You fine folks know more about this stuff than I do. I'm just looking for help on getting my combination racing/non-racing motor running...

                          Thanks again.

                          Comment



                          • #14
                            Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                            Just feed her 50:1 and don't exceed about 6,000rpm, DBS, and you will be fine.

                            You probably need either a stator or a powerpak. Sorry I can't tell you which.

                            Perhaps someone will come along with good advice and no colossal ego to protect.
                            sigpic

                            Comment



                            • #15
                              Re: 1977 Johnson 75HP Bad Pack, Stator, or Timer Base

                              My two cents on the matter is as follows:

                              First, the 75hp triples was not the only OMC triples to have compression values in the 140 - 150 range. My 1972 Johnson 65hp motor had values in the high 140s when I bought it a little over three years ago, and it still shows values in the 130s, even though I have run it for hundreds of hours since then. It also runs very nicely the way it is, TYVM.

                              The only thing that concerns me about your motor, is that the difference between the low number and the high number, is approaching the 10% differential that most people don't like to see. For the cost and time involved, I might be tempted to slap a new head gasket in the motor, just to see what happens. A manual decarb of the head and pistons might not be a bad idea, while your "in there." None of this is to say, however, that your motor will not be perfectly usable for some time to come.

                              I would be less inclined to think in terms of a timer base for an "instant" ignition failure on all three cylinders, than I would of either a powerpack or a stator. I also would not be looking at the ignition coils as a starting point, simply because it would be extremely rare for all three of them to "roll over and die" at exactly the same time. As JB said, the odds of this just don't favor the supposition that this is the problem.

                              On the other hand, this scenario is quite common in regard to powerpacks and can happen with a stator. Since, in my experience, the powerpacks seem to be more "finiky" than stators, I'll stick my neck out and say that my guess is that this is where your problem lies. Even if it is not, it has also been my experience that motors this old, tend to need a complete ignition system rebuild for maximum reliability, so it isn't the end of the world if the stator turns out to be the culprit.

                              As far as internet sources of info for "ohming out" ignition components, go with the OEM service manual for your year and model. If I had a buck for every time I have seen incorrect info published on the internet or in generic manuals for these motors, I could buy you a new powerpack as a gift.

                              BTW, Sierra and CDI make ignition parts for these motors. Since the parts that OMC/BRP is selling these days for motors of this vintage are aftermarket items anyway, you may as well save a few bucks by going directly to aftermarket sources.

                              Let us know how you make out.
                              Please don't PM me on advice issues - let's keep that in the forums, so that everyone can benefit. Please note that I do not email PDFs, etc. I have a bandwidth limited aircard for internet access. My avatar does not mean I have any offical link to iboats. I just like it!

                              Comment

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