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  1. #1
    jetskibum1's Avatar
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    155 giving me nightmares ...

    Hey guys I am posting in this section as I know it is where all the clever techs look.
    I have a 155 hp single engine sports ( 2003 )boat and it has had a rebuild by a repair shop after it dropped a valve.
    When it came to me it would not start.
    I found the cam timing to be out some and reset it. Now it winds over for very short bursts then the starter disengages and you have to hit it again. This is not its issue as persistence and it will start. ( but I do wonder if there are ramifications of incorrect placement of the encoder wheel that will not trip a crank shaft to cam shaft implausible fault )
    Once it starts it runs at about 1800 rpm for a few secs then jumps up to about 3200 and stays there.
    Now the throttle body idle screw had been butchered before I got it so I put on a complete second hand unit from another ski complete with idle bypass valve and tps. No change
    Reset TPS
    Remove intake manifold and check seals, ran up with hose off the front of throttle body and stuck my finger over idle bypass hole and it stopped instantly so I have discounted an air leak.
    Swap engine temp sensor with exhaust temp sensor and both read correct in BUDS either way.
    Air temp sensor reads correct.
    No faults recorded or active while running
    ECU replaced with new one, install set and adj TPS..... No change

    What am I missing here ?????

    I even hunted for a OPAS steering sensor which it did not have as I thought it may be upping the revs for something like that.

    Any one have any ideas ??
    Thanks in advance


  2. #2
    Boost addict hotbird's Avatar
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    so the ecu is commanding the IAC to that RPM level.

    Need to find out why.

    The boats up the idle during steering?

    engine temp sensor reading correctly?

  3. #3
    GOT BOOST? Dockside's Avatar
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    I had a 155 sportster an if i remember correctly i did increase the idle when steering but don't thinking was as much as your seeing. my boat also had the same starting issue and it was never apart. Have you swapped the starter to rule that out? Does it have a high idle in the water?

  4. #4
    jetskibum1's Avatar
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    Quote Originally Posted by hotbird View Post
    so the ecu is commanding the IAC to that RPM level.

    Need to find out why.

    The boats up the idle during steering?

    engine temp sensor reading correctly?
    Temp sensors are all reading ok on buds and I have swapped them all to eliminate
    I cant find an idle up set up on it and the steering is straight so I assume that would be ok
    Thanks for your thoughts, I have just spent another day on it and got no where.
    I tested the comps and they are ok
    It has had head welding done I can see through the middle inlet valves.

  5. #5
    jetskibum1's Avatar
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    Quote Originally Posted by Dockside View Post
    I had a 155 sportster an if i remember correctly i did increase the idle when steering but don't thinking was as much as your seeing. my boat also had the same starting issue and it was never apart. Have you swapped the starter to rule that out? Does it have a high idle in the water?
    I have not replaced the starter as I don't want to make a new one second hand if I cant fix the main issue.....its a bit like no win no fee to be fair on the customer eh

  6. #6
    jetskibum1's Avatar
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    [QUOTE=hotbird;2342236]so the ecu is commanding the IAC to that RPM level.

    Need to find out why.

    The boats up the idle during steering?

    QUOTE]
    Also if I start the ski and quickly un plug the idle bypass stepper...... the revs still go up like it is in timing
    I have done fuel pressure testing today and it is rock solid at 44 even when the revs go up
    engine temp sensor reading correctly?[/

  7. #7
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    Air leaks? Pinched manifold o ring or similar?

  8. #8
    Boost addict hotbird's Avatar
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    Ok thats strange.

    Vaccume leak?

    On cars ive seen the map sensor do weird things like that.

  9. #9
    GOT BOOST? Dockside's Avatar
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    Do you have a smoke machine you can use to double check for leaks?

  10. #10
    jetskibum1's Avatar
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    Quote Originally Posted by brendanm View Post
    Air leaks? Pinched manifold o ring or similar?
    I just took the manifold off for the second time and put a cup of brake cleaner into it.......no leaks
    O rings all mint and if you stick your hand over the throttle body it stops like a light switch

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