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Problems: 1976 85 HP V4 Johnson

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  • Problems: 1976 85 HP V4 Johnson

    Hello,

    I am trying to help my brother get his boat going, long distance. He is in NY, and I am in FL. I have more experience than him, but you guys are the infinite source of info. I was hoping, together, iboats, my brother and I could solve his problems.

    He told me that the engine runs fine on land, and idles up in the water with the warm up lever, but when he tries to plane out, he has no power. He said it sounds like the engine is running on one or two cylinders. he can't even plane, so I bet it's only firing on one cyl.

    He checked spark with a new spark plug grounded to the block, and found weak blue spark, even on all four. I'm not sure he could tell the difference between massive blue and weak spark without seeing them side by side, but nonetheless, he has even spark. Next, he switched out power packs, with a used one we had lying around. No change. He is trying clean and rebuild the carbs as we speak.

    I told him to check compression, but he doesn't have a gauge. He will check this tomorrow, but I think he is going to water test the boat tomorrow also.

    What do you guys think, especially about the spark?

    Any thoughts are welcome.
    Those people who don't provide closure on the threads they started SUCK!


  • #2
    Re: Problems: 1976 85 HP V4 Johnson

    we need a compression check. could be linc n sinc, if they are not coordinated, they will act like that, flood before the spark catches up.
    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.

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    • #3
      Re: Problems: 1976 85 HP V4 Johnson

      We are going to do a compression check ASAP. When you do it, what is the correct procedure? I have been told to pull one spark plug out at at time, insert the meter hand tight, remove all plug wires from the remaining plugs then put throttle at WOT. In order to do this, you will have to get around the neutral safety switch. I would just keep the ign key off and jump the solenoid. Good so far?

      When it comes to link 'n sync, how do you know if it needs to be done? I have always started with the engine in neutral, and checked the gap between the throttle and the carb, then compared the two results. This would be the sync part right? Meaning that the tow carbs were syncronized? I know there is a spark advance issue also, but this is where it gets fuzzy for me. I know there is a linkage that can be adjusted, opening and closing the throttle, very minimally. Is that all?
      Those people who don't provide closure on the threads they started SUCK!

      Comment



      • #4
        Re: Problems: 1976 85 HP V4 Johnson

        Take all the plugs out. Use a screw in compression tester that will hold pressure until released by you. Ideally the engine should be warm and well lubricated. Consistency is the point. You take all of the plugs out to maximize the compression. Same with a spark test. The engine needs to turn 300 RPM for the ignition to work as intended.

        Make sure to use the short fitting or the piston will hit it. It is important to record the measurements cylinder by cylinder.

        Comment



        • #5
          Re: Problems: 1976 85 HP V4 Johnson

          If you look up under the flywheel, you can check to make sure that the potting on the stator isn't melted and you can check to see if the timer base is connected and that the advance is moving freely.

          If you want to recheck the powerpack wiring I can post the wiring diagrams. The wires to the ignition coils are all the same color so its easy to get them out of order.

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          • #6
            Re: Problems: 1976 85 HP V4 Johnson

            Thanks for the quick reply. I guess ayou don't have to open the throttle to WOT?
            Those people who don't provide closure on the threads they started SUCK!

            Comment



            • #7
              Re: Problems: 1976 85 HP V4 Johnson

              2 cycle crossflow engines have multiple large ports on each side of each cylinder that are passed by the piston on each compression stroke. So no, it does not matter if the throttles are open or not.

              Comment



              • #8
                Re: Problems: 1976 85 HP V4 Johnson

                Thanks.

                I have seen the stator potting melt before, I will check with my bro to see if it has. Should this be ok if the advance is movint easily? If it is sticky, which I have seen, should you just pull the fly wheel, stator, timer base and just clean with degreaser or acetone then put back together? Do you have to replace stator or reseal it with something? I believe the CID wires are all ok. I know he has a few cracked coils. Theey are all sparking evenly, are they ok?
                Those people who don't provide closure on the threads they started SUCK!

                Comment



                • #9
                  Re: Problems: 1976 85 HP V4 Johnson

                  If the ignition coils are warped, swollen, melted , cracked or discolored, they should be replaced. Ignition coils are unpredictable and can bench test fine and fail when warm. A bad ignition coil can destroy a good powerpack.

                  An open circuit, such as the kind that sometimes occurs with a bad rectifier, can allow battery voltage to reach ignition components such as the stator and cook them.

                  Sometimes the wires drag and keep the timer base from moving properly.

                  All of ground wires need to be checked and thoroughly cleaned on the motor, especially the ones on the component rack where the ignition coils are nested. Include the grounding strap between the rack and the starboard cylinder head in the cleanup.

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                  • #10
                    Re: Problems: 1976 85 HP V4 Johnson

                    Thanks. What do you think about a lower unit for this engine that can only get forward or reverse, based on the shift cable adjustment, but not both at the same time? Shift dogs worn out?
                    Those people who don't provide closure on the threads they started SUCK!

                    Comment



                    • #11
                      Re: Problems: 1976 85 HP V4 Johnson

                      The shift rod has a foot on it that makes that end not adjustable, but the top has a swivel barrel that can be out of sync. It should be turned all the way down and then turned no more than two turns to get the flat face facing forward.

                      Once that is correct and the gearcase remounted, you need to take the control arm all the way forward and then back to neutral and disconnect the shift cable at the engine.

                      Now with cable disconnected, using the shift lever and bellcrank at the engine, shift into reverse and back to neutral and test the propeller to see if it is locked. Then do the same with forward and back to neutral and test to see if the prop is locked.

                      If you find that the propeller can be turned in neutral from both tests, adjust the cable length with the black shift trunnion adjustment nut until the cable slips on without moving the shift lever at all. Then reconnect.

                      It is not unusual for the prop shaft to move some while the gearcase is in neutral, especially when on muffs. If it moves a lot, you may be a few years late on an oil change.

                      It is virtually impossible to have no point at which there is neutral, there is just too much space between the gears for the dog to run free.

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