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'88 70hp multiple problems

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  • '88 70hp multiple problems

    Hi all it seems i've joined the not-so-exclusive club of 70hp owners experiencing no power under load.
    Motor idles sweet on muffs..........
    Have had carbies off cleaned thoroughly, replaced raycor water seperator, replaced inline filter from inside cowling, flushed tank thoroughly, replaced spark plugs ......
    To begin with i could not get any revs over about 1500rpm - either in the water or with muffs, after cleaning carbs i can now get revs only with fast idle lever with muffs on, in the water it idles lower and will not rev above 1500 rpms.
    Why will it rev up on muffs but not in the water??
    Added to this i have now noticed water leaking from around spark plugs that was not present before and the telltale intermittently squirts water, when it does this water is very hot! have had hose off and cleaned it to ensure no blockages, water flow is still very weak.

    Any help greatly appreciated, thanks in advance.

  • #2
    Check compression on all cylinders and make sure spark is strong and blue using a spark tester. If compression is not good you may have hurt the motor running lean or hot.
    If that is all good then it is back to the fuel.
    Motor needs more fuel to produce power so there is no load out of the water.
    Sounds like you have a water pump problem or blockage in the cooling passages. When was the last water pump and thermostat change?

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    • #3
      Hi is there anybody that can help me,im still new in this and want to ask a question about my 85 yamaha,where and how do i do this?

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      • #4
        havent tested compression as yet, spark seems strong on all 3 cylinders and as i have only just aquired this motor i dont know of the last impellor change - am planning on doing this tomorrow, at which time i will try and flush the cooling passages. Pulled the cover off the thermostat housing today to find that the thermostat is non existent....
        Have also removed and disassembled fuel pump, whilst both diaphrams appear to be intact, the one on the outlet side ( without the spring ) appears to be stretched out of shape quite a bit and the gasket (also from that side) is perished and split in places. when removing the diaphram from the inlet side i noticed a lot of crap behind it - presumably in the void from where it draws air... is this normal? Looks like a fuel pump kit and water pump kit next on the to do list...

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        • #5
          check compression first. If that is bad then you may not want to buy the other parts.
          No thermostat means someone has been doing things incorrectly to this motor so there is no telling what all you will find.
          Hope you did not pay good money for it.

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          • #6
            Just a quick update, checked compression today to find cylinders 2 & 3 fairly even at around 115 psi, unfortunately #1 has little to no compression. time to pull her down and see what problems lie within.... fingers crossed its just a head gasket.
            Anyone know the best place to get top end rebuild kits in Australia???

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            • #7
              no such thing as a top end kit on that motor.
              its not a moto cycle nor a jet ski.
              its an outboard.
              time for a tear down and inspection.

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              • #8
                Originally posted by rodbolt17 View Post
                no such thing as a top end kit on that motor.
                its not a moto cycle nor a jet ski.
                its an outboard.
                time for a tear down and inspection.
                Well thank you for your invaluable contribution, perhaps (just a suggestion) instead of belittling me on the correct terminology for a powerhead gasket/seal kit (6 to 1, half a dozen to the other) you might advise where one might be sought ( as requested kindly).
                Oh and i am quite aware it is an outboard not a motor cycle / jetski - not sure what gave it away though, maybe the propellor..............

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                • #9
                  Info for those who might be following this thread with similar problems - found a powerhead gasket/seal kit on Ebay, located in QLD, Australia (bonus!!!) for $140.00 Quite a reasonable price tag compared to quotes from genuine dealer.
                  I guess the moral of the story is it pays to shop around......

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                  • #10
                    but without a teardown for inspection buying anything is most likly a waste of money.
                    that kit contains a lot of gaskets/seals your simply NOT going to use.
                    sorry you dont like corrections.
                    however I actually do this stupid work for a living.

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                    • #11
                      maybe you need an altenator?
                      The mechanic vs the Customer
                      http://www.xtranorma

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