User Tag List

Page 1 of 2 1 2 LastLast
Results 1 to 15 of 16
  1. #1
    Join Date
    Jul 2018
    Location
    Grosse Ile, Mi
    Posts
    28
    Thanks (Given)
    1
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    '87 Mercury 115, running poorly in gear only

    Hey Folks,

    I know OMC crossflows like the back of my hand, but I'm new to Mercury. I'm helping a buddy out.

    Okay, so, Merc 115 inline six, 2 stroke, carburated, 1987.

    Starts, idles fine, can even rev out in neutral in the water. But, as soon as I put it in gear, stutters, sputters, and can't build rpm.

    Fuel pump has pressure, checked the plug wires with my timing light, replaced a damaged coil pack, they all seem fine.

    The problem started on the water. Boat was running fine. Shut it down, hung out, and fired it back up after a while and ran like crap in gear.

    Lower end trouble? High speed jets? Electrical? Get me started on something?

    Thanks again,

    The Last One

  2. #2
    Join Date
    Sep 2011
    Location
    maryland
    Posts
    1,560
    Thanks (Given)
    262
    Thanks (Received)
    178
    Likes (Given)
    1709
    Likes (Received)
    1309
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    How's the compression for the motor? It sounds familiar to me.............with my own motor. You may find low compression is the culprit.

    High speed jets wouldnt affect the low speed "in gear".

  3. #3
    Join Date
    Apr 2001
    Location
    Michigan
    Posts
    15,422
    Thanks (Given)
    214
    Thanks (Received)
    475
    Likes (Given)
    7697
    Likes (Received)
    4259
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    stator.

  4. #4
    Join Date
    Jul 2018
    Location
    Grosse Ile, Mi
    Posts
    28
    Thanks (Given)
    1
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Update!

    So, I checked compression. It was good on all cylinders 92-98 psi. I couldn't check cylinder six because it was too low in the cowl to get my gauge in there, but it's likely good given the others are fine.

    Checked coil packs. Each reads 0.92 - 0.98 ohms, except one which I just replaced and reads 1.41 ohms.

    So, now I'm pulling the carbs to clean jets.

    Capt. Insane-o, how do I check the stator?

    Thanks again,

    TLO

  5. #5
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Good strong battery, carbs open, 3-4 pumps to 92 psi?

  6. #6
    Join Date
    Jul 2018
    Location
    Grosse Ile, Mi
    Posts
    28
    Thanks (Given)
    1
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by FMP View Post
    Good strong battery, carbs open, 3-4 pumps to 92 psi?

    I don't recall if I had the carbs open. 😬

  7. #7
    Join Date
    May 2006
    Location
    Sugar Grove IL./Eagle River WI.
    Posts
    410
    Thanks (Given)
    1
    Thanks (Received)
    6
    Likes (Given)
    43
    Likes (Received)
    81
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Capt.Insane-o View Post
    stator.
    need a dva meter to be sure

  8. #8
    Join Date
    Jul 2018
    Location
    Grosse Ile, Mi
    Posts
    28
    Thanks (Given)
    1
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    SS170: I have a digital voltmeter.

  9. #9
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

  10. #10
    Join Date
    Apr 2001
    Location
    Michigan
    Posts
    15,422
    Thanks (Given)
    214
    Thanks (Received)
    475
    Likes (Given)
    7697
    Likes (Received)
    4259
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    If thats a reptuble compression gauge they won't run on 98 psi. The bores are tapered and it will fall on it's face at throttle pick up.

  11. Likes keefallan liked this post
  12. #11
    Join Date
    Feb 2014
    Location
    Missouri
    Posts
    1,212
    Thanks (Given)
    2
    Thanks (Received)
    66
    Likes (Given)
    12
    Likes (Received)
    83
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Idle set out of water. Seen it done many times.

    plus the other stuff.

  13. #12
    Join Date
    Jul 2018
    Location
    Grosse Ile, Mi
    Posts
    28
    Thanks (Given)
    1
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hmm, guess I'll recheck compression with WOT.

    But they're all real close to eachother, so I doubt that it.

  14. #13
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Yeah, 6 beautiful consistent tried bores. Great motor though, fix it right whatever it is. Hoping it's just hose tuned as mentioned above.

  15. #14
    Join Date
    May 2006
    Location
    Sugar Grove IL./Eagle River WI.
    Posts
    410
    Thanks (Given)
    1
    Thanks (Received)
    6
    Likes (Given)
    43
    Likes (Received)
    81
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I'd still lean toward the stator (low speed windings). Running fine, shutting down, then runs like crap seems more like ignition. A DVA tester is an adapter that plugs into your Fluke, it measures peak voltage for that split second that a meter alone cannot read. Try and find one and follow the CDI troubleshooting guide. You will then be sure if it has anything to do with ignition.

  16. #15
    Join Date
    Feb 2015
    Location
    Ontario
    Posts
    8,091
    Thanks (Given)
    205
    Thanks (Received)
    321
    Likes (Given)
    1921
    Likes (Received)
    2005
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    What boat is it on? I mean worst case you needed to do the bores you could work some magic for some gains. Many say just leave it stock and that's true but that's not the only way.
    These folks were highly recommend by a pure inline guru for their machining , if you need it .
    http://www.wintechenginemachine.com/index.htm

Page 1 of 2 1 2 LastLast

Similar Threads

  1. New to me 2014 Optimax 300 running poorly
    By TraceF3 in forum Technical Discussion
    Replies: 46
    Last Post: 10-12-2018, 02:31 PM
  2. Mercury Tech: Is This Going To End Poorly?
    By adorabill in forum Technical Discussion
    Replies: 5
    Last Post: 06-30-2008, 07:50 AM
  3. 2.4 efi runing poorly
    By DK in forum Technical Discussion
    Replies: 7
    Last Post: 08-08-2003, 04:27 PM

Tags for this Thread

Posting Permissions

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