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  1. #1

    2016 Ultra 310X misses at full throttle

    Hello Forum
    I stripped out the complete engine, pump, fuel system and electronics from a 2016 Kawasaki 310x (that only had 5 hours total on the boat since new) and installed it into an 11' aluminum white water jet boat.
    The engine performed perfect for the first 10 hours and now misses on hard acceleration and full throttle.
    It seems to get worse the longer you run it as in only 10-15 minutes.
    At first it starts to miss at 6900 RPM and as time goes by the miss starts at lower to say 6200 rpm.
    Normally the engine will rev to 7400 rpm.

    When you put it in ECO mode it runs without missing but has less power, acceleration and speed as expected.
    I tried new spark plugs and checked all electrical and plumbing connections.
    From my years of turbo charging car engines, it feels like the ECU is not getting the message to give more fuel under boost from the supercharger.
    On cars the presence of boost signals the fuel pressure regulator to raise the fuel pressure and the boost pressure to the ECU also increases the duration of the injectors.

    The 310X fuel pump is in the tank and is designed to not have a fuel return line to the tank.
    Next I will check the fuel filter/sock in the tank but after only 15 hours I doubt that is the issue.

    I assume the mass air flow sensor controls the fuel flow under boost.

    I would appreciate your consideration and suggestions.
    Thanks
    Highroad 2

  2. #2
    Belt slipping? Tensioner working correctly and not stuck?

  3. #3
    mwhc
    Checking the super charger belt was a good idea that I had not thought about.
    I removed the hose from the supercharger to the intercooler and it makes a big blast of wind when you rev the motor.
    The belt and tensioner appear to be in excellent condition.

    I took apart and checked all the electrical connections and coated the pins with dia electric grease.

    I removed the fuel pump and cleaned and back flushed the fuel filter/sock, made sure the tank was venting, removed the fuel and filtered it to make sure there was no debris or water in it.

    I also hooked a fuel pressure gauge directly to the fuel pump and it made 57 psi.

    I took it out several times today with little or any improvement.

    Nearest dealer is 3 hours away so ordered a shop manual from Kawasaki.

    I wonder if the spark plug wires are failing, but doubt it since they only have 15 hours since new.

    Any other ideas????

    Thanks
    Highroad

  4. #4
    @Highroad 2

    Did you find solution for this? I'm facing the same issues with my 310x

  5. #5
    steve45's Avatar
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    Hey, Highroad 2, how about some pictures of your project?

  6. #6
    Update on my 2016 ultra 310x engine and pump that is in a boat that misses at full throttle.

    I would post photos if there was an easy way to do so from an iphone.

    Fuel pressure guage indicated around 55 psi fuel pressure at idle and 30 psi at full throttle/boost, which would be a good reason for the engine to miss.
    I installed a new stock replacement pump from kawiperformance.com and now the pressure at full throttle goes from 55 to 50.
    Steve at kawiperformance says the fuel pressure should always be at 55, idle to full boost.
    So I removed the internal fuel pressure regulator and filter and installed an external fuel pressure regulator and filter that returns excess fuel to the tank.
    The fuel pressure can now be adjusted externally so I set the pressure at 60 at idle and at full boost it goes to 55.
    Steve says that I need a higher volume pump when using an external regulator because 30% of the fuel gets returned to the tank.

    Now that I kind of have the fuel pressure issue figured out it still does not run right.
    By having adequate fuel pressure it now revs to 8000 when it was 7400 max with bad fuel pump.
    Problem is that it will rev immediately to 8000 and then in 2 seconds start to miss and drop to around 7300.

    Steve at kawiperfomance thinks that I may have what he calls a "traction control" issue.
    I purchased the 310x service manual and have yet to find anything about "traction control"
    He said the traction control can be removed by re flashing the ECU.

    Can someone clue me into what traction control on a ultra 310x is and is that why some users install a SCOM device?

    Thanks
    Highroad

  7. #7
    .
    Last edited by madandy; 07-03-2020 at 07:23 AM.

  8. #8
    Take the time to smile sirbreaksalot's Avatar
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    Quote Originally Posted by Highroad 2 View Post
    Update on my 2016 ultra 310x engine and pump that is in a boat that misses at full throttle.

    I would post photos if there was an easy way to do so from an iphone.

    Fuel pressure guage indicated around 55 psi fuel pressure at idle and 30 psi at full throttle/boost, which would be a good reason for the engine to miss.
    I installed a new stock replacement pump from kawiperformance.com and now the pressure at full throttle goes from 55 to 50.
    Steve at kawiperformance says the fuel pressure should always be at 55, idle to full boost.
    So I removed the internal fuel pressure regulator and filter and installed an external fuel pressure regulator and filter that returns excess fuel to the tank.
    The fuel pressure can now be adjusted externally so I set the pressure at 60 at idle and at full boost it goes to 55.
    Steve says that I need a higher volume pump when using an external regulator because 30% of the fuel gets returned to the tank.
    That is incorrect to saying that.... doesn't matter if the pressure regulator is intank or external, they only return the excess fuel pressure above the set point..( not a % )
    The real issue is more than likely the cheap WALBRO copy fuel pump you probably got sold.


    Now that I kind of have the fuel pressure issue figured out it still does not run right.
    By having adequate fuel pressure it now revs to 8000 when it was 7400 max with bad fuel pump.
    Problem is that it will rev immediately to 8000 and then in 2 seconds start to miss and drop to around 7300.

    When are you feeling this power reduction?...... WOT on smooth or rough water
    Steve at kawiperfomance thinks that I may have what he calls a "traction control" issue.
    ( note all 310's have it lol ) it not a desease you catch.... and it not an issue as in a fault !!
    I purchased the 310x service manual and have yet to find anything about "traction control"
    He said the traction control can be removed by re flashing the ECU.

    Can someone clue me into what traction control on a ultra 310x is and is that why some users install a SCOM device?

    Traction control was a description that we started using back in 13.5> to describe the new feature of the ECU's in the new skies coming out
    Predictive RPM control is a more accurate description, it ONLY activates in high RPM maps, its designed to control RPM if the ECU thinks the rate of rpm increase is going to exceed the internal RPM values ( 99% of the time you only feel it when at WOT and the ski comes unhooked due to leaving the water), The ECU see's the sudden rapid RPM rise and knows its out of the water so it activates RPM control, then when you hit the water a split second later you feel a slight dead spot before the power comes back on fully.
    the skies without this feature just pull instantly once you reload the pump because the engine power wasn't interrupted....

    hopefully that makes sense lol


    Thanks
    Highroad
    Kspeed Reflash........is the ticket for your ECU Re-flash....
    especially when you do the currency exchange..

    Waz
    Last edited by sirbreaksalot; 07-05-2020 at 04:36 AM.

  9. #9
    Let me out of here......I need to go on Greenhulk!
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    Does the 310 use a speedo paddle wheel and did you install it on your boat?


  10. #10
    Hurricane1000's Avatar
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    Check your supercharger belt....make sure that there are no leaks spraying on the belt which can cause it to slip.....
    This slip changes everything! Motor will not run correctly with the belt slipping or not enough tension on the belt tensioner....
    Do a search on it....

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