Logo
Click forPleasurecraft Marine parts and manuals!
Results 1 to 6 of 6
  1. #1
    Join Date
    Sep 2009
    Location
    , Minnesota,
    Posts
    9

    Default 1979 Nautique 351 floods after turning off engine

    Trying to fix neighbor's 351 in a well- maintained 1979 Nautique. Holly 4600 series carb professionally rebuilt for this problem a year ago - only about 10 hours on the rebuild and problem is back. It looks like too much gas dripping out the primary venturis at idle, but idles pretty good, but when shut off, gas pours out the primary venturis for 10 to 15 seconds flooding the engine. It will not start until it cools off unless you open the throttle all the way and crank for 10 seconds to deflood. Some gas even came out bowl vent. I've rebuilt over 100 carbs over the years, so I took a look. Everything looked fine but I replaced float and float valve needle and seat anyway with genuine Holly parts - problem seems slightly better (no gas out bowl vent) but still definitely there. Economizer valve appears to be OK. The secondaries are behaving OK. Float assist spring appears OK. Float level OK. Float not binding - that formed brass metal part that partially shields the bowl's vent outlet passage is mounted properly - not hanging down to hit the float. When carb is apart, I can turn the float chamber/float valve assembly upside down so the float closes the valve by gravity and I can't blow into the gas line, so valve is working. I'm thinking the float is somehow not cutting off gas and bowl is overfilling but don't know that for sure. Choke wide open.
    Has anyone else had this problem? and how was it fixed?
    Thx,
    Dave

  2. #2
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: 1979 Nautique 351 floods after turning off engine

    It has to be at the float needle and seat possible small crack at the threads for the seat? May not be able to see it when the seat is out. Is it a mechanical fuel pump or electric?

  3. #3
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: 1979 Nautique 351 floods after turning off engine

    You should have no more than 6psi fuel pressure at the carb inlet.

  4. #4
    Join Date
    Sep 2009
    Location
    , Minnesota,
    Posts
    9

    Default Re: 1979 Nautique 351 floods after turning off engine

    Quote Originally Posted by kimcrwbr1 View Post
    It has to be at the float needle and seat possible small crack at the threads for the seat? May not be able to see it when the seat is out. Is it a mechanical fuel pump or electric?

    Thanks for the reply. Will try to check for cracks in threads. The fuel pump is mechanical.
    Dave

  5. #5
    Join Date
    Sep 2009
    Location
    , Minnesota,
    Posts
    9

    Default Re: 1979 Nautique 351 floods after turning off engine

    Quote Originally Posted by kimcrwbr1 View Post
    You should have no more than 6psi fuel pressure at the carb inlet.

    I think I have an old vacuum gauge around here that has a fuel pump pressure test function with the needle going the other way - I'll see if I can find it and check. If pressure was too high, I'd expect the secondary bowl to be flooding too, but it's not.
    Dave

  6. #6
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,765

    Default Re: 1979 Nautique 351 floods after turning off engine

    4600 series???

    on a 4160, you can usually drop the float level an additional 1/8" without any impact...also, if there's enough clearance, you could add an insulator block.

Similar Threads

  1. engine floods
    By ajverdi2 in forum Johnson Evinrude Outboard Forum
    Replies: 4
    Last Post: 06-17-2017, 08:34 PM
  2. no fire in plugs prop turning while turning over engine
    By 69 grand larson in forum Identifying Model / Year / Horsepower
    Replies: 3
    Last Post: 04-30-2016, 06:29 PM
  3. 1993 9.9hp engine floods
    By ajverdi2 in forum Johnson Evinrude Outboard Forum
    Replies: 1
    Last Post: 08-14-2010, 07:39 PM
  4. 1979 Johnson 55HP difficult to get started floods easily
    By marksimm1 in forum Johnson Evinrude Outboard Archive
    Replies: 1
    Last Post: 08-11-2009, 02:46 PM
  5. Engine floods out
    By marv in forum Archive 2003-2009
    Replies: 1
    Last Post: 09-04-2002, 02:54 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •