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  1. #1
    Join Date
    Dec 2013
    Posts
    10

    Default Vapor Lock + RPM + Prop selection Questions 2005 Mobuis LSV

    Hi there I am in South Africa and we do not have a dealer out here so I hope somebody can help me with some of these questions. I Have a 2005 Mobius LSV EFI
    1) Vapor Lock - When I use the boat for about 30 min and stop for more than 20 min the boat does not want to run. I starts for a few seconds and then stops again. If I leave it for about 1-2 hours it starts no problem. I have read a lot about vapour locks on the forum but have not found the answer to resolving this.
    I have drained and cleaned the tank, installed new fuel filters, installed a water separator.
    When the problem occurs and I feel the steel fuel pipe on-top of the fuel pump it is very hot.

    2) I cannot seem to get my RPM over 4000 RPM when I am alone on the boat running on full throttle. What RPM should I expect to get and what could the reasons be that I am only achieving 4000 RPM

    3) I am considering changing my prop. We are about 1400m (4200ft) above sea level and we use the boat mostly for wakeboarding. What type and size of prop do you suggest.

  2. #2
    Join Date
    Aug 2011
    Posts
    955

    Default

    Did you replace the fuel pump? You did everything but that..

    Sent from my Nexus 5 using Tapatalk
    2002 Moomba Mobius LSV - Sold
    2006 Moomba Mobius LSV

  3. #3
    Join Date
    Jan 2008
    Location
    Tallahassee, FL
    Posts
    11,084

    Default

    Welcome Chari! We will do our best to help you and anyone else around the world who loves the MOOMBA brand (Supra too!). Can you post the numbers listed on your prop? Sometimes the boat will perform better with a different propeller. Also, do you run ballast? If so, how much do you run? What bags, weights and locations? What types of activities do you and your group do when you go out on your boat?

    The more information you give us the more specific the advice we provide will be. Glad to have you aboard!
    My Mom said I'm not allowed to get wet!
    2008 LSV
    2000 Outback LS (sold)
    Exile Tunes
    PWI
    LLTR!!!!!!!!



  4. #4
    Join Date
    Nov 2003
    Location
    Land O Lakes, Florida
    Posts
    5,827

    Default

    for the vapor lock, it helps to keep the blower running for a little while after shutting off to help flush out the hot engine air, this can help but is not a fix. think it has to do more with the fuel pump and lines getting so hot.

    prop--look the rear of it, there should be some numbers stamped into it, need to know what you running now. but think that motor should rev up to round 5k
    Hey, Its Moomba time

    13 Mobius LSV
    08 Mobius LSV-sold
    03 Mobius LSV-sold

  5. #5
    Join Date
    Jul 2002
    Location
    London Ontario Canada
    Posts
    1,839

    Default

    Quote Originally Posted by Charl View Post
    Hi there I am in South Africa and we do not have a dealer out here so I hope somebody can help me with some of these questions. I Have a 2005 Mobius LSV EFI
    1) Vapor Lock - When I use the boat for about 30 min and stop for more than 20 min the boat does not want to run. I starts for a few seconds and then stops again. If I leave it for about 1-2 hours it starts no problem. I have read a lot about vapour locks on the forum but have not found the answer to resolving this.
    I have drained and cleaned the tank, installed new fuel filters, installed a water separator.
    When the problem occurs and I feel the steel fuel pipe on-top of the fuel pump it is very hot.
    Next time out lift the engine hatch after you have run it for 30 mins, then after a 20 min wait , see if it starts and stays running, if it does then you have confirmed vapour lock. Then the best way to solve may be install a high volume, low pressure pump on your line as close to the fuel tank as possible
    Last edited by DOCDRS; 12-27-2013 at 06:37 PM.
    09 21v LAUNCH

    run your engine after you change your oil
    68 th Member. WS420,HSE Revolution, OJ 466, Acme1157,1100 sacs,Kicker HLCD's n IX500.4, Supra Coolies
    Doug

  6. #6
    Join Date
    Sep 2005
    Location
    Claytor Lake, VA
    Posts
    291

    Default

    Quote Originally Posted by Charl View Post
    Hi there I am in South Africa and we do not have a dealer out here so I hope somebody can help me with some of these questions. I Have a 2005 Mobius LSV EFI
    1) Vapor Lock - When I use the boat for about 30 min and stop for more than 20 min the boat does not want to run. I starts for a few seconds and then stops again. If I leave it for about 1-2 hours it starts no problem. I have read a lot about vapour locks on the forum but have not found the answer to resolving this.
    I have drained and cleaned the tank, installed new fuel filters, installed a water separator.
    When the problem occurs and I feel the steel fuel pipe on-top of the fuel pump it is very hot.

    Quick temp fix is keep some bottles of water in the cooler and pour on the fuel pump and lines when you have vapor lock. Permanent fix is add the 2nd fuel pump.

    2) I cannot seem to get my RPM over 4000 RPM when I am alone on the boat running on full throttle. What RPM should I expect to get and what could the reasons be that I am only achieving 4000 RPM

    Check your linkage at the throttle body. I had to adjust mine so it was full open at full throttle. I think RPM limit is4800.

    3) I am considering changing my prop. We are about 1400m (4200ft) above sea level and we use the boat mostly for wakeboarding. What type and size of prop do you suggest.
    I have a 14.25 x 14 prop with 1400 lbs of ballast but am only at 1800 ft.
    2005 Mobius LSV

  7. #7
    Join Date
    Dec 2013
    Posts
    10

    Default

    Hallo Parrothd - I have not replaced the fuel pump as yet. First want to be sure it is the pump. Do you know if a faulty fuel pump could also cause the boat not to exceed 4000 RPM.

  8. #8
    Join Date
    Dec 2013
    Posts
    10

    Default

    Quote Originally Posted by kaneboats View Post
    Welcome Chari! We will do our best to help you and anyone else around the world who loves the MOOMBA brand (Supra too!). Can you post the numbers listed on your prop? Sometimes the boat will perform better with a different propeller. Also, do you run ballast? If so, how much do you run? What bags, weights and locations? What types of activities do you and your group do when you go out on your boat?

    The more information you give us the more specific the advice we provide will be. Glad to have you aboard!
    Hallo kaneboats - Just took the boat out of the water today
    I have a MVC HC OJ 13,7 x 17.5
    I run the following Ballast -Right back +/- 200kg & -Left Back +/- 200kg & Centre Ski Hatch +/- 200KG
    We mostly use the boat for wakeboarding and surfing.
    We are +/- 4000 ft above sea level.
    As mentioned the boat does not exceed 4000 rpm (but I am not sure if this is a fuel pump or prop or other problem.
    What prop would you recommend for my use?

  9. #9
    Join Date
    Dec 2013
    Posts
    10

    Default

    Quote Originally Posted by moombadaze View Post
    for the vapor lock, it helps to keep the blower running for a little while after shutting off to help flush out the hot engine air, this can help but is not a fix. think it has to do more with the fuel pump and lines getting so hot.

    prop--look the rear of it, there should be some numbers stamped into it, need to know what you running now. but think that motor should rev up to round 5k
    Hallo Moombadaze
    I have a MVC HC OJ 13,7 x 17.5
    I run the following Ballast -Right back +/- 200kg & -Left Back +/- 200kg & Centre Ski Hatch +/- 200KG
    We mostly use the boat for wakeboarding and surfing.
    We are +/- 4000 ft above sea level.
    As mentioned the boat does not exceed 4000 rpm (but I am not sure if this is a fuel pump or prop or other problem.
    What prop would you recommend for my use?

  10. #10
    Join Date
    Dec 2013
    Posts
    10

    Default

    Quote Originally Posted by VA LSV View Post
    I have a 14.25 x 14 prop with 1400 lbs of ballast but am only at 1800 ft.
    Thank you for the reply
    I have a 13,7 x 17,5
    Any idea what prop I should use for my conditions (I am 4000 ft above sea level_
    Also what does the 13,7 and the 17.5 stand for?

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