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  1. #1
    Join Date
    Jun 2018
    Location
    Penfield NY
    Posts
    4

    Default hard starting 350 Magnum......help needed

    I have a 1993 Crownline 21 CC with a 350 magnum, 4 barrel Carter AFB. The carb is where the problem lies. I have been battling this for 4 years now since I bought the boat and have decided to try and fix it. When I arrive at the boat after it setting for 5-7 days it needs about 30 full seconds of cranking before it starts to get gas. I was told by a local marina that with Carter AFB's if they sit for a week or so the bowl drains dry. So that sounds right on because after I crank and fill the bowl it will then start. A day or 2 later its ok, but after a week it needs a lot of cranking. Once the bowl fills and it starts then another issues arises because the choke spring is bad. I bought a new one online for $60.00 and it was the wrong one. But even with a bad / not operating choke I can get by until it warms up. The it re starts pretty good once warmed up.

    I think I would just like to put a new /different carb on it but I don't know which one to put on ? Also, is a 2 barrel and option ? The boat needs a 16 pitch prop to get on plane and our speed limit is only 25 MPH , so do I need a 4 barrel?

    I would really appreciate any advise.
    thanks much
    Bob

  2. #2
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    4,882

    Default Re: hard starting 350 Magnum......help needed

    The boat needs a 16 pitch prop to get on plane and our speed limit is only 25 MPH , so do I need a 4 barrel?

    I think you need to find out why its not running correctly A 21 footer with 260 horse should move very briskly on the water.
    Most use the 14 x 19 or 14 x 17 props .What is your max RPM with that prop? you should be over 4000 rpm at least

  3. #3
    Join Date
    Jun 2018
    Location
    Penfield NY
    Posts
    4

    Default Re: hard starting 350 Magnum......help needed

    With the 16 pitch prop My Max rpm is 4300 and the boat goes 30mph. BUT its a heavy boat and I usually have about 8-10 people in it. and the longer the season goes the more crud grows on the bottom of the boat gets even harder to get on plane . I have to move people forward to get the boat on plane when the boat is loaded with people. Tough to do with a cuddy, thats why I wish the boat was an open bow. I've used 19 and 18 pitch 4 blade props but the 16 4 blade prop runs just fine. 4 blades are much better then the 3 baldes. Thats not really my problem. The more I thought about it I have to stay with a 4 barrel because I do not want to change the 2 barrel intake manifold. I just want the boat to start easier and not have to crank it for 30 seconds. A couple of years ago I changed the wires , plugs cap and rotor and that helped. But it has always started HARD. And i think that motor has 280 horsepower. It only has 530 hours on it.
    should I have the carb rebuilt? or I think I would rather just replace it. But replace it with what ?
    thanks

  4. #4
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    7,943

    Default Re: hard starting 350 Magnum......help needed

    I don't think you have a carb issue....what you describe is pretty common here in the mid-atlantic region....the gasoline they sell now evaporates very quickly in a hot engine box, especially after shutdown.....some live with it and use the starter.....some have switched to electrical fuel pumps and add prime buttons, and some use the manual squirt bottle method.....which is cost effective but time consuming and potentially dangerous....

    I'd also suggest you verify the hull ratings....I'd bet you are normally overloaded.....

  5. #5
    Join Date
    Jun 2018
    Location
    Penfield NY
    Posts
    4

    Default Re: hard starting 350 Magnum......help needed

    You make a lot of sense. All valid reasons for the bowl going dry. I'll let you know what I find out.
    thank you

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