new to jet boating
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new to jet boating

  1. #1
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    Default new to jet boating

    I just got a 1979 belmont jet boat, it has a 454 bb chevy with berkeley pump. it runs great just been siting for years. I changed the oil and filter,cap,rotar,plugs and went over all the basic stuff and it runs great. i took it out for the first time and found out the intake manifold gasket was shot,so i fixed it and it runs strong...BUT when i hit it wide open it goes good for 20 seconds or so then the rpm's drop... goes from 5200 to about 4700 still wide open and slows down a lot and runs a little hot, some times it goes to 4000 and gets a little too hot(has not got hotter than 210-220) seems to me thats a little too hot when going fast...its almost like i sucked up some seaweed or something,but when i go about 10 mph it cools down then i can get on it agen for just a little bit then same thing happens. has anyone ever had this problem??????

    thanks for your time

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    Senior Member nosfomoco's Avatar
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    Something is definetly not right! What water temp does it run at idle? Also what kind of fuel system is it running(Carb, fuel pump, etc.) does it have headers or logs?
    1978 Eliminator Sport Cruiser 20.5ft BBF 460!

  4. #3
    Senior Member jet460's Avatar
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    Sounds like fuel starvation/lean out.

    Mine did exactly the same thing until I replaced the cheezy 25gph/3 psi Pep Boys fuel pump the PO had on there, and replaced it with a 90gph/7 psi pump from summit.

    Night vs day.

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  6. #4
    "Mad" Member Jet Mad's Avatar
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    Check if you have a gate valve on the water feed from the jet to the engine. If you have one, check the setting.

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  7. #5
    NorCal HotBoats Chili's Avatar
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    Quote Originally Posted by ridinfool View Post
    I just got a 1979 belmont jet boat, it has a 454 bb chevy with berkeley pump.
    Curious.. do you have any pics.?

    I have a 74 Belmont Jet and have a couple questions..
    1. Where is the VIN/HIN number.? (do you have a plate from Belmont on yours, & where is it located on the hull)
    2. Where are you located..? (West Coast, South, East, Midwest, etc.)


    Would love to see more pics of another Belmont Jet.
    74 Belmont - 455 - Berkeley

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  8. #6
    Senior Member GA Jet's Avatar
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    Quote Originally Posted by jet460 View Post
    Sounds like fuel starvation/lean out.

    Mine did exactly the same thing until I replaced the cheezy 25gph/3 psi Pep Boys fuel pump the PO had on there, and replaced it with a 90gph/7 psi pump from summit.

    Night vs day.

    x2

    Totally agree with Jet460 here, check you fuel pump output and possibly the jetting in you secondaries.

    Does the motor hesitate when the secondaries open up? a lean mixture can affect your temp to some extent but I think something else might be goin on there too.

    Do you have over-transom or through transom exhaust?

  9. #7
    Senior Member sleekcraft137's Avatar
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    Quote Originally Posted by jet460 View Post
    Sounds like fuel starvation/lean out.

    Mine did exactly the same thing until I replaced the cheezy 25gph/3 psi Pep Boys fuel pump the PO had on there, and replaced it with a 90gph/7 psi pump from summit.

    Night vs day.
    i had the same issue and replaced my pump with a holley blue pump. Its sitting at 14 psi......too much? should i back it down to 8 lbs or so?

  10. #8
    Senior Member jet460's Avatar
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    Quote Originally Posted by sleekcraft137 View Post
    i had the same issue and replaced my pump with a holley blue pump. Its sitting at 14 psi......too much? should i back it down to 8 lbs or so?
    I guess that depends on carb type, how much HP you are getting.
    My boat is in the 300-350hp range and runs at 5-7psi on dual Holley 450's
    A Holley needle and seat only holds up to about 8psi, I think, so any more than that is just a flood.

    The Summit pump works perfectly for me.

    Carbs don't really care too much about pressure as long as the bowls stay full.
    Last edited by jet460; 05-26-2010 at 04:41 PM.

  11. #9
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    Quote Originally Posted by nosfomoco View Post
    Something is definetly not right! What water temp does it run at idle? Also what kind of fuel system is it running(Carb, fuel pump, etc.) does it have headers or logs?
    it runs about 130 at idol. i have a holly carb and its a mechanical pump not electric and i have logs

  12. #10
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    Quote Originally Posted by GA Jet View Post
    x2

    Totally agree with Jet460 here, check you fuel pump output and possibly the jetting in you secondaries.

    Does the motor hesitate when the secondaries open up? a lean mixture can affect your temp to some extent but I think something else might be goin on there too.

    Do you have over-transom or through transom exhaust?
    i have through transom exhaust

  13. #11
    Senior Member GA Jet's Avatar
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    Quote Originally Posted by ridinfool View Post
    i have through transom exhaust
    hmm nvm then. The OT exhaust on our sleekcraft was rigged by an idiot so long story short, they made my engine run hot lol.

    doesnt sound like the problem for you though

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