Mercruiser 3.0L choke question

Discussion in 'General Discussion' started by 55Trucker, Sep 16, 2022.

  1. 55Trucker

    55Trucker New Member

    17
    Aug 15, 2022
    Otisfield, ME
    1998 SeaRay 175 Bowrider with Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    Hi everyone, and happy Friday.

    We recently bought a 1998 SeaRay 175 Bowrider. As the temp outside gets colder, the motor gets increasingly difficult to start. It has the Mercruiser 3.0L/135hp engine. Yesterday I pulled the flame arrester off, and figured I'd take a look at was is going on when I try to start it. The first things I noticed are a) the choke was open, and b) the choke appears to be electric.

    Can someone please send me a pointer to read about how this choke works, how to adjust it, etc? When it is 58 degrees outside I was surprised that the choke wasn't already closed when I began trying to start it. Thank you.
     
  2. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    2014 Cobalt R5
    Volvo Penta V8-300 DP
    I am going to assume you have a 2bbl Mercarb? If so, the choke adjustment is the round thing on the left side of the carburetor with two wires coming out of it. To adjust loosen the two screws and turn it toward the stern for more choke and bow for less. It is an electric choke, so when you turn the key it should close, pump the throttle and that sets the takeoff (opens the choke slightly so the engine will start). Once it starts it should idle high and as the engine warms the choke should open and the idle will come down. If it is not doing this, then check for 12v at the choke.

    Here is the service manual for Mercarb:
     

    Attached Files:

  3. 55Trucker

    55Trucker New Member

    17
    Aug 15, 2022
    Otisfield, ME
    1998 SeaRay 175 Bowrider with Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    Thank you, this is exactly what I needed.
     
  4. GypsmJim

    GypsmJim Well-Known Member

    827
    Aug 8, 2018
    Western New York
    '19 SPX 190 OB, 150 & 5 Mercs
    '17 Whaler 150 Montauk
    '15 Yamaha FXHO
    '60 Mulray Dinghy
    '52 Lyman 15'
    Mercury 150 4-stroke
    68 Outboards representing 11 manufacturers
    That's a 22 year old boat. I had the same model, but a 1984. I had the same problem at about the same age. I simply replaced the choke and spring assembly and set it to the mid setting. It worked fine after that for another decade. Sold it at 35 years, so I don't know after that.

    I have an old classic car with a spring choke. They only last so long before the spring loses its effectiveness.
     
    Nater Potater and Bill Curtis like this.
  5. 55Trucker

    55Trucker New Member

    17
    Aug 15, 2022
    Otisfield, ME
    1998 SeaRay 175 Bowrider with Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    Mercruiser 3.0 and Aplha1 Gen 2 outdrive
  6. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    2014 Cobalt R5
    Volvo Penta V8-300 DP
    Never heard of that manufacture, but that looks like a mercarb choke.
     
  7. 55Trucker

    55Trucker New Member

    17
    Aug 15, 2022
    Otisfield, ME
    1998 SeaRay 175 Bowrider with Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    Mercruiser 3.0 and Aplha1 Gen 2 outdrive
    One more question on this topic: I was watching a youtube video of a guy adjusting the electric choke on his boat. When he took the flame arrestor off on a presumably cold engine, his choke was wide open, like mine was. He said something I couldn't hear about the throttle, and the choke snapped closed. What is the mechanism that makes the choke close? I would have guessed that it closes simply when the choke coil cools down. Is there another mechanism that closes it?
     
  8. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    2014 Cobalt R5
    Volvo Penta V8-300 DP
    This guy explains how the choke works much better than I can. Mikes carburetor - I watched his videos and used his rebuild kit for my Mercarb.

     
  9. GypsmJim

    GypsmJim Well-Known Member

    827
    Aug 8, 2018
    Western New York
    '19 SPX 190 OB, 150 & 5 Mercs
    '17 Whaler 150 Montauk
    '15 Yamaha FXHO
    '60 Mulray Dinghy
    '52 Lyman 15'
    Mercury 150 4-stroke
    68 Outboards representing 11 manufacturers
    The choke spring is what makes the choke close on a cold engine. But the idle cam holds the choke mechanism from its last warm setting. Thus, in order to get the choke to close you must slightly advance the throttle to release the cam.

    Not rocket science. It's just like old carbureted cars. You pump the throttle to activate the choke, and then leave the gas pedal down slightly as you hit the ignition switch. (all quite clearly described in the owner's manual - available online free from Mercury Marine if it didn't come with a used boat)

    If you do all that and the choke still does not close, then it needs to be adjusted by turning the black housing (containing the spring) until the choke is fully closed.

    The rest of the story is that these springs lose tension after years of use. Thus, if you HAVE to make an adjustment after 20 years, you really should replace the assembly with a new spring. Because even if your adjustment works on an initial cold startup, the rate of spring movement won't be good enough to make the engine run well during the entire warm up period.
     
    techmitch, Nater Potater and scoflaw like this.
  10. dvx216

    dvx216 Well-Known Member SILVER Sponsor

    Feb 1, 2012
    Catawaba Island,Oh.
    2001 340 sundancer 8.1
    8.1s 370 v drv.
    My first boat had an 120 Hp 4cyl. In the spring it was not uncommon for the choke spring to pull by the and need removed and put back into place.
     

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