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  1. #1

    Just bought two MSX 150's.. Looking for some advice.


    I just purchased two MSX 150's. One seems to run fine and does the normal high rev at start since it is not in the water. I have not pulled the reverse lever on it yet.. The other starts but has a real low idle and feels like something is plugged when you rev it.. The guy I purchased it from said he was riding normal speed and then boom out of no where low rev..

    both skis are very clean on the inside engine compartment. I did not see any water inside at all ( I know this can be a common problem with these skis)

    First thing I am going to check is the intake grate. I want to make sure he did not suck up any debri.. (wouldn't that be an awesome fix!) Next I will make sure the exhaust is clear and I will check the oil for any water.

    I want to check the intercooler also but appears like that is a pain in the ass.. anyone have some easy steps for this or short cuts? I also will check the map sensors and make sure there is no oil in them.. I was told you can get them from an auto parts store for way cheaper than a Polaris dealer.. anyone have the part or number I want to ask for?

    Anything else I should look for?? anything I want to check on these? I have always been a seadoo guy so these are new to me... but any project is fun as hell! well depending on the cost lol

    Thanks again for any help..

    If anyone is close to Sacramento I will probably sell these in a package deal. I would like 5k for both with a double trailer.. However, always open to offers.

  2. #2
    found this also... anyone have any bypass shortcuts?

    "The System Interface Box (SIFB) is a mushroom shaped module that plugs into the wire harness above the battery... below the ECU. If you're having starting/stopping or rev limiting at 3400rpms... this is the likely culprit."

    I found this for a possible MOD ..

    "There now exists an aftermarket SIFB (called BT-5033) which can be had from WeberPower. This does handle reverse rev-limiting as the original, but removes the auto-powerdown feature so be sure to pull your lanyard."

  3. #3
    martincom's Avatar
    Join Date
    May 2010
    Brainerd, MN
    I want to check the intercooler also but appears like that is a pain in the ass.. anyone have some easy steps for this or short cuts? I also will check the map sensors and make sure there is no oil in them.. I was told you can get them from an auto parts store for way cheaper than a Polaris dealer.. anyone have the part or number I want to ask for?
    About the only instance the intercooler becomes an issue is if the watercraft is capsized. Assuming they still have the original oil tanks and no "catch can" modification, oil flows from the oil tank, through the breather hose, to the air intake. In turn, it makes it way through the intercooler and coats the MAP sensors with oil. Once coated with oil, they no longer report correct barometric pressure. As the readings are out of range, the ECU goes into "limp mode".

    When I had this occur, I never replaced the MAP sensors, I just pulled them, flushed them with tuner wash (electronic component cleaner in an aerosol can) and re-installed. The issue with the intercooler is that it is still coated with oil and once you've cleaned the MAP sensor, it doesn't take long for more of that oil, that was retained in the intercooler, to coat them again. So the intercooler needs to be cleaned to remove the oil residue. As you figured out, no small job. The work around is to disconnect the intercooler inlet and outlet, connect a shop vac to one end and add Dawn wish washing soap and plenty of hot water to the other. Flush until clean. Still not easy, but nothing is on MSX150, but it beats removing the intercooler, which is pretty much an engine pull.

    The fuel injection system is made by Bosch. I believe the Bosch part number is stamped on the sensor and from that, you should be able to locate replacements. If not search, the forum, it has been posted. K447 may have them posted on his info pages.

    Tip: Google or other search engine works much better than the forum search tool. I have found the forum search tools is only effective for single word searches.

    The real fix for the oilingestion was the updated oil tank--which is now NLA and wasn't a cheap fix. The cheap fix is to disconnect the breather hose and connect it to a "catch can".

    The weber engines have a number of other issues:

    -the nikasail plating of the cylinder walls is known to fail
    -the water pump gear is known to fail
    -the overheat sensors are, for the most part, a one time fail
    -the ECU tends to run rich and there is an aftermarket re-flash/map to correct this

    I had purchased two new and sold both of them when they had less than 60 hours on them. At the time, I tallied up the known repair costs, without addressing the cylinder plating, and it was around $2000.00 for each to correct the issues, with no allowance for my own labor. I decided to cut my losses and sell them. They are a nice ride and handle rough water great. At the time, they were probably the fastest thing on the water at a top speed of 65 - 70 mph.

  4. #4
    Thanks,.... I purchased these to resell them... i knew I would be buying a polaris which was not the best machine... probably why they quit making them.. I got both with a trailer for 3k.. once I fix this issue I will sell them for about 4k out here in Cali..

    Thanks for the intercooler short cut... if thats an issue I will try it.

  5. #5
    OK So...... The map sensors are squaeky clean!! I did the jumper and nothing.... I checked the intake grate no blockage.... SOOOO being the whiley veteran mechanic that I am ... I went back to basics... lest check the plugs...... boom a dark black fouled plug!! ordered plugs from Oreilly.. going to grab batteries also... lets see what this does! Stay tuned ... I will update tonight!

  6. #6
    ripcuda's Avatar
    Join Date
    May 2010
    Newman Lake, WA
    Make note of the exact RPM you are limited to (if consistent). You can tell alot about issues based on the max RPMs you are seeing.

    If ~3400... then it's likely the SIFB module... if you have an original one, pull it and do the paperclip mod to eliminate it as a possibility. (search 'MSX paperclip mod'). The paperclip is in-place of the original SIFB or aftermarket BT-5033.

    Are you seeing any dash indicators when it won't rev? Could be common, exhaust manifold overheat sensor (switch). It limits RPMs to around 1800.

    Also check your turbo isn't seized. A seized turbo restricts intake air and won't let it rev. Remove intake hoses from turbo to IC and IC to hardpipe... then unbolt IC (2 bolts) and push it forward out of the way. Remove single bolt holding plastic "airbox" to front of turbo inlet. Push "airbox" forward and stick your fingers into the turbo inlet... see if it freely spins and/or has any shaft play.

    Also... agree with your idea to inspect the pump. I'd just pull the main pump (the 4 LONG bolts + steering linkage + reverse linkage + 2 siphon hoses) out the back. Tug hard... it'll pull right out the back. Could be a swollen wear ring dragging on the impeller.


  7. #7
    Mike Greenwood's Avatar
    Join Date
    Jun 2015
    Tulsa, Oklahoma
    There is a easier way to clean the 150-110 intercoolers. You will need a shop vac that is set up for wet removal. Disconnect the both charge air hoses off the I/C.
    Purchase some Purple Power degreased that is readily available at most auto parts stores. Get a couple of gallons of water boiling. Mix a 1/2&1/2 solution of hot water and degreaser. If your shop vac is one of the bigger units. It will have a hose that perfectly fits where the charge air hoses go. Go ahead and hook up the vacuum hose to one end. It does not matter what side you pick. Now take one of the charge air hoses that you previously took off and hook it up to the other side. Make sure to have the loose end of the charge hose pointing up. This will assist in the complete flooding of the I/C.
    now fill the I/C with your degreaser mix and let sit for a few minutes. Kick on your shop vac and evacuate as much of the soiled water as possible. Dump out your shop vac and wipe it clean. Don’t skip the cleaning process with the shop vac. It is your best way to grade the cleanliness of the I/C. Now repeat this process until your extracted fluid matches what you are pouring in.
    Now comes the task of drying out the I/C. Having compressed air will greatly assist with this chore. Although it is not absolutely necessary, it speeds things up. To dry, leave your shop vac on and wait. If you have compressed air, attach a blower and assist the drying process by agitating the moisture in the I/C by blowing in the side that you previously were pouring your solution in.
    hope this helps

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