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  1. #1

    1994 polaris sl 750 dies after running it all out for a 5-10 minutes

    I have a 1994 Polaris sl750 I bought last summer. The guy I bought it from elminated the oil pump and went too all premix ( 40:1 mix ). I have 170 lbs of compression in each cylinder. Only took it out twice and this has happened twice. I idled it out to the lake and got on it. Runs fine for about 10 minutes and dies. Let it sit for a half hour or so and it will start right up. Has anyone run into this before? I am lost. I really would appreciate some advice on this problem. Would really like to get some ridding time in. When its running its wonderful and fast.

  2. #2
    I'm addicted to Polaris PWC ghostinstallations's Avatar
    Join Date
    Aug 2011
    Rochester, New York
    Welcome to The Hulk!

    Are you running race gas? Stock the compression should be more like 120-135 psi.

    Click the link in my signature for alot of great troubleshooting info.

  3. #3
    No I am running 87 octane with synthetic oil.

  4. #4
    Polarisitis loonatik's Avatar
    Join Date
    May 2010
    Tampa, FL
    Did it sound like it wants to start or just cranking and nothing?

  5. #5
    it turns over but it doesnt start till it cools off. Until it shuts down it runs fine.

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    170 psi is way too high compression for pump gas. You'll need to use race fuel with numbers like that.

    150 psi is about the limit for 92 octane.

    You're most likely overheating the pistons and seizing in the cyls.

    Might want to take the heads off and have a look for any damage.

  7. #7
    RLACEMAN's Avatar
    Join Date
    Aug 2011
    Random Lake WI
    Double check your compression if its still the same the engine isn't siezing then. 170 is very high, did this guy you bought it from do any mods to the engine?

    Or try another compression tester to make sure you have a correct reading.

    Also if the fuel you use contains ethanol 87 is not acceptable you must use 89 or higher or the engine will not live long.

    If the compression is really 170 then you have to use 91 & then it should not contain ethanol.

    The 780 engines have 145-155 compression & can run on 87 without ethanol & must use 89 or higher with it.

    You should be ok with 91 if compression is 170 but you are right at the limit.

    If everything checks out it could be a weak fuel pump, does this ski have the triple outlet fuel pump or the old style single?
    Last edited by K447; 09-02-2012 at 01:46 PM.

  8. #8
    Tony's Avatar
    Join Date
    May 2007
    North Carolina
    Check for spark. If no spark do stator/ignition checks before it cools down.

    Quote Originally Posted by abbieg250 View Post
    it turns over but it doesnt start till it cools off. Until it shuts down it runs fine.

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