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  1. #1

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    2003 Polaris msx 140 HO wont does not rev up

    Hi I am brand new to owning a PWC and Green hulk so please be patient with me. I am fairly handy and have worked on my own cars, motorcycles, and boats. bought two 2003 MSX 140ho's. the #1 ski starts and idles fine but when I give it gas its seems like it has no power and wont rev up.

    the #2 the guy told me he was having issues and last year had the fuel pump replaced-its would turn over and try to start but would not. so I decided to work on this one first. pulled plugs and inspected gap and ensured I had spark and compression- both were good on all three cylinders.
    Then pulled 3 injector assembly lose and pressed start to see i was getting fuel and it was, but injectors looked dirty so I removed and cleaned, while pumping injectors I noticed the fule looked funny. it looked like almond milk or skim milk and I could see water in fuel. I emptied fuel pump dry and looked it to see a white silty looking material in the bottom. so I washed out the tank with hot water and a little simple green, dried it, and put new gas in it.

    With the injectors still off I thought i would just pump through to the fresh gas and be good to go. Not the case. the fuel is still milky looking. there is no water anymore but still this white looking fuel. I pumped at least 1 gallon about (7 oz. at a time) of the new 5 gallons of gas through the system into a clear container and still no clean fuel coming through. so I am thinking that there is something dissolving in the system like a line or screen or filter .
    has anyone experienced this?

    AS a note I took some gas and oil mix in a spray bottle and can keep the machine running just fine by spraying into throttle body I kept it running for at least five minutes ( with water source connected )

    I need a place to gain knowledge and assistance.
    thanks for any info.

    I am new so please if you use acronyms let me know what they are the first time used.

  2. #2
    radio-active's Avatar
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    I won't speculate on why your fuel is milky. I can't imagine a component in the system dissolving.

    5 minutes running out of the water is a long time, you may be damaging your thru hull bearing which is cooled by the lake water. And remember that you can't run these engines on premix alone -- there must be working oil injection for the bottom end.

    The other ski may have low fuel pressure -- you can measure that at the fuel line schrader valve with a proper pressure gauge (many common ones don't work, won't reach the valve core). If it's not in the 20 - 25 range your regulator may have dropped off the pump. There are a couple of well vetted fixes for the regulator problem, search the forum. In any case that fix is mandatory on both skis. Running the engine with low fuel pressure, even briefly, can destroy your engine.

    You could also have a throttle position sensor problem.

    I am certain others will weigh in here with more helpful suggestions.

  3. #3

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    Thanks for that tip about running out of the water. I assumed I could hook up the hose and it would take the place of the cooling system from the lake water.

    I will check the pressure on the fuel, do I just use a normal tire pressure gage?
    I will also look up that fix on the pressure regulator.

    Can you tell me how to verify or test the oil pumps to ensure they are working. I pulled the line off the throttle body and pressed the "start" to rotate the engine and no oil was injecting. but when I ran it it was smoking so I am pretty sure its getting oil. I just want to really be sure

  4. #4
    Click avatar for tech links/info K447's Avatar
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    Note that ‘hook up the hose’ to the water manifold bar on top of the engine, also does not supply ANY cooling water to the EMM.

    That Reverse Flush garden hose connection on the top of the engine is essentially useless.

    Reverse flush does not properly cool the engine, as some cylinders get more water flow than others. If the thermostat or pressure bypass valve are not present then almost no water goes through the engine, most of the water just dumps out the water exit fitting into the pump tunnel.

    Reverse flush does not ‘flush’ the engine water jackets with sufficient vigor to accomplish much at all.

    And as noted the jet pump and driveline shaft seals are not water cooled when the engine is running on land.

    There is a place to connect a garden hose that will provide proper engine cooling and feed the EMM, but it is not a quick connect. It is the main 3/4” water feed hose, located very low in the hull next to the pump tunnel, on the right side.

  5. #5
    martincom's Avatar
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    #1 Check the throttle position sensor (TPS). It has three leads: one is ground, another is 5 volts and the third will be the wiper and the voltage will vary with throttle position. Fully closed is just less than a volt and wide open is just below or above 4 volts.

    #2 The replacement fuel pump could be trouble. Most of the aftermarket pumps, except the Quantum, draw far too much current. See this thread for details. Check the current draw of the pump: Remove the large, 40 pin connector, from the Engine Management Module (EMM). Locate pin 40, which has a brown wire terminated on it. Ground pin 40 through a current meter. Be careful not to deform or damage the pin receptacle. The engine need not be running. If the pump draws more than 3.0 amps, it is too much. OEM pumps draw less than 2.0 amps.

    Both #1 & #2: The fuel pressure regulator (FPR) falling off is a very common problem and must absolutely be reinforced before operating. No ifs or buts. The regulator falling off while running will result in a lean mixture that can cause catastrophic damage in minutes. See this thread. And this thread for details. Check the intake screen, at the bottom of the pump (not the filter at the bottom of the canister), for foreign matter.

    As the oil tank has to come out to pull the fuel tank ahead or out, add an O-ring or two to the body of the oil level sending unit and a gear clamp around the tank neck. They are known for leaking profusely and even coming out. Clean the oil filter by back flushing or replace.

    It is also a good opportunity to correct the reverse mechanism, as it should be accessible. See the stickies for details.

    Through hull bearings and seals should be replaced every 100 hours on a MSX.

    Did you make sure to re-install the injectors in their original positions? Their flow characteristics are measured during manufacturing and programmed into the EMM, per assigned cylinder. Do not intermix the bottom nozzle between injectors. If you need to purge or flush fuel, it would be much better to gently pull the fuel line tees from the injector body.

    The fuel lines are probably hard as a rock from age/heat. Disturbing them at all will almost always result in their leaking. It would be a good time to replace fuel lines, with marine grade fuel hose, and only utilize Oetiker clamps.

    You can find more detailed service info here.


    Trim the flame restrictor (air cleaner) boss that digs into the top of the intake air temp sensor. See K447's info pages for details.

    You can purchase an affordable fuel pressure gauge here.


  6. #6

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    well I thank you for all this info. I have a lot to do.
    I am not sure I did install the injectors back in the correct spot so I may be in trouble on both of my ski's.
    the good news is I did clean the contacts on the tps and try and it still did not idle. the guy that sold these to me gave me two brand new tps units, i installed one and it did not change a thing, it does idle when I disconnect the tps though.
    so anyway I noticed the plugs in the machine were not the correct number so I bought some PZFR6H plugs, installed them tonight before reading this and the engine stared right up and idled fine. I did not run more than 30-60 seconds cuz I learned there is no cooling today in this forum.

    now both of my skis start and idle, but when you give it throttle they both bog down like they have a govenor on them.

    i will look into all you mentioned and will do the preventative stuff as well.

    any ideas on this lack of rpm when giving throttle?

    thanks much

  7. #7
    martincom's Avatar
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    Start with checking the fuel pressure. It should be approximately 25 psi. If the regulator fell off, there is still enough fuel pressure for it to start. Once you have a gauged connected to the Schradrer valve test port, if the fuel pressure is low, pinch off the return line between the Schrader valve and the fuel tank, with a needle nose pliers. If the pressure jumps to 30 psi or thereabouts, the FPR has fallen off. You can ground pin 40, as I described in my previous post, to run the fuel pump without starting the engine.

  8. #8
    casey67's Avatar
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    Reverse ? Unplug the reverse motor. I have a Genesis here that is stuck in reverse ( reverse gate removed), although gauge shows forward.

  9. #9

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    2003 MSX 140 ho idle but wont rev up

    I purchased two of these machines.

    I now have both of them able to idle and start.
    both machines when I give them gas hesitate and bog down like they have no power.
    I purchased a gas pressure test gage and the #1 ski has zero pressure when running, is that possible?
    Ski #2 has 20psi when idle and when i give throttle it does not go up.

    what should the gas pressure be?
    And what would cause this issue?
    thanks


  10. #10
    martincom's Avatar
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    Please do not create a new thread on the same issue. I answered your questions in your other thread on this topic. Creating a new thread will not give you different answers.

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