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  1. #1

    Help... 2003 msx 140 ho problems

    I own a 2003 Polaris MSX 140 ho. Owned for two seasons. Here is my current problem..

    The problem started out by the jet ski bogging down while riding hard... not fast but jumping waves, spinning around.. the bogging occurred while having the jet ski out twice. The second time the bogging became more normal. The jet ski showed signs of normal idle, engine was a little warm to the touch but not really hot. I could easily start the jet ski up and it would drive good up until 30 mph or so. when you hit the throttle it would pick up speed but it would just die after hitting about 48 or so. the jet ski became hard starting after this occurred. after letting the jet ski skit for about a minute it would start back up and the same symptoms would happen. I am pretty handy along with having another identical jet ski I did the following at the lake..

    swapped injectors and emm together (injectors stayed in correct cyl.)
    swapped tps sensor
    swapped coil packs
    swapped good battery due to turning over

    seems like a lack of fuel upon demand of more throttle...

    checked the fuel pump pressure regulator hose in the pump. The hose was off but there was a pressure regulator hose on the air outlet.. strange?? so there are two on my jet ski... Someone was in there...

    Repaired the fuel pressure regulator hose. brought to lake and same issues happened as before only getting worse.

    started looking into the cooling portions of the jet ski.. everything seems ok there.

    jet ski wont even start now, backfires a little. but while looking in engine compartment noticed the oil pump bracket by the front of the engine is not mounted in at all...

    low compression now, pulled heads and jugs off. lost skirts on 1 and 3 cyl. ??

    what happened.... and why..

    now my questions are.. was the bogging down in the beginning the start of internal engine parts? I can get two new pistons... should i split the crank case. the engine turns over all day...

  2. #2
    Join Date
    Apr 2009
    Jacksonville FL
    There are several symptoms/issues listed.

    When you say oil pump bracket, do you mean the oil pump itself? With this bracket not mounted (if it is not the oil pump) does it stop the oil pump from operating (cable not actuating the arm on the oil pump)? Do the index marks on the oil pump align?

    Have you checked your fuel pressure? K447 has links posted on how to do this.

    Engine backfire and hot ... Have you driven your ski in shallow water? It does not take much sand to clogg your cooling system. One low point that is very susceptible to clogging is the water passage through the stator cover. If this becomes clogged it will starve the emm of cooling water. One symptom of a damaged emm is backfireing. Can you blow low pressure air through the water ports on the stator cover? Also, pull the cooling lines off of the emm and make sure it is not clogged or the nipples melted.

    What do you mean when you say "Lost Skirts"? Is the area on the pistons under the rings scored or broken? How are the cylinder walls? Any scoring or plating chipped? If the pistons are missing chunks of metal, the metal will be in the lower end (crankshaft/cases).

    K447's links in his signature are a wealth of information. He has replied to many, many threads.

    I would verify the oil pump was operational and that the fuel pressure regulator did not fall off in the gas tank (see K447's links for full discription). Additionally, check those cooling lines and the emm cooling passage (it is aluminum and corrodes internally).

    It sounds like the internal engine degridation was caused by either a lean fuel condition (pressure regulator), insufficient lubrication (oil pump bracket), or overheated/failed emm.

    I am an aircraft mechanic 22+ years and have done a lot of work on cars/boats and a few jet skis. I have a 03 MSX 140 that I purchased as a basket case. I spent last winter building/fixing/troubleshooting it. It is now a very fast reliable ski. I used this forum for alot of info. I am giving you this info to let you know that I specialize in high performance aircraft, not jet skis. I am making recommendations off of personal knowledge and do not work on ski's for a living. I am sure a few more senior board members will jump in with more info or be able to elaborate more!

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