Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 12 of 12
  1. #1
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default mercruiser ignition problems

    ok guys heres what i have its a 1986 mercruiser 140, with points ignition, i have a problem with keeping it running. it will stall out on me after a few minutes on the muffs at idle, @650 rpm., i did a complete tune up to see if that would help and its still dying out on me..if i take a wire from the +12 side of the battery to the + side of the coil it will run great, whats the best way to isolate whats wrong? i disconnected my temp wire as not to burn out the points with batt voltage. i also have a mercruiser resister kit installed in the harness going to the coil.

  2. #2
    Honorary Moderator Emeritus Don S's Avatar
    Join Date
    Aug 2004
    Location
    Western WA.
    Posts
    62,323

    Default Re: mercruiser ignition problems

    Disconnect your boats fuel system at the engine fuel pump and hook up an outboard tank and see what it does.You could have problems with the fuel pickup, the antisiphon valve, hoses sucking air instead of fuel due to bad hoses or wrong clamps, plugged fuel tank vents or low spots in vent hose.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  3. #3
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default Re: mercruiser ignition problems

    don, i cleaned the antisiphon valve, replced all fuel filters, installed a new factory mercarb, getting great fuel pressure, why is it if i hook up 12 volts to the plus side of the coil it runs better

  4. #4
    Honorary Moderator Emeritus Don S's Avatar
    Join Date
    Aug 2004
    Location
    Western WA.
    Posts
    62,323

    Default Re: mercruiser ignition problems

    You also did a tuneup. After you changed the points, did you set the dwell, and then reset the timing and adjust the carb?
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  5. #5
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default Re: mercruiser ignition problems

    don yes i did,

  6. #6
    Chief Petty Officer
    Join Date
    Jun 2003
    Location
    Vancouver, Canada
    Posts
    413

    Default Re: mercruiser ignition problems

    What is the voltage between the positive side of the coil and the block when it starts acting up?

  7. #7
    Petty Officer 1st Class
    Join Date
    Jun 2003
    Location
    S. Ga.
    Posts
    239

    Default Re: mercruiser ignition problems

    You have made no mention of the coil. Did you change it. The coil is mounted close to the block and gets pretty hot after a few minutes. An intermitten coil will give you some similiar symptoms. If it is an 86 model coil it is due for a change. often mistaken for carb problems.Uncle Dave

  8. #8
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default Re: mercruiser ignition problems

    i'll check in the morning and post

  9. #9
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default Re: mercruiser ignition problems

    coil has not been changed to my knowledge

  10. #10
    Moderator achris's Avatar
    Join Date
    May 2004
    Location
    I come from a land down-under...Perth, Australia
    Posts
    15,187

    Default Re: mercruiser ignition problems

    You also need to check the resistance from the 'ON' side of the key switch to the coil "+". It sounds like you have a resistive wire going faulty. Does the engine slowly die out, or is running great then just die, like the key has been turned off?You say you have a restistive wire kit installed. Is this in series (in line) with the original or does it replace the original?Chris............
    The world takes on a whole new perspective when viewed from 100' below...



    1972 Bertram 'Bahia Mar' 20
    2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
    **
    Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
    **
    Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/

  11. #11
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default Re: mercruiser ignition problems

    Chris,it dies a slow, reistor replaces the original

  12. #12
    Seaman
    Join Date
    Nov 2004
    Location
    Long Island, N.Y.
    Posts
    54

    Default Re: mercruiser ignition problems

    thanks guys it was a bad coil, replaced it today it runs great now

Similar Threads

  1. Ignition problems - 1987 3.0L Mercruiser
    By ExUSCG-QM in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 5
    Last Post: March 2nd, 2009, 12:55 PM
  2. 228/305 mercruiser ignition problems
    By dacaptain in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 16
    Last Post: March 20th, 2007, 01:29 PM
  3. Mercruiser 5.7 efi Ignition problems?
    By badal in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 4
    Last Post: September 26th, 2005, 11:43 AM
  4. 1975 GM Mercruiser Ignition Problems
    By wiltie in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 1
    Last Post: August 6th, 2003, 07:06 AM
  5. Ignition problems w/ 4.3 v6 Mercruiser- one bank not functioning...
    By Orange_Spitfire in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 7
    Last Post: August 1st, 2003, 12:37 PM
  1. iboats Forum Directory - Over 100,000 forum posts organized by topic