Ignition system issue

Discussion in 'Outboard Maintenance' started by richwalker71, Nov 8, 2011.

  1. richwalker71

    richwalker71 Well-Known Member

    294
    2
    391
    Give it throttle and it tops out around 3k. Don't think its a fuel issue, just did a carb job and checked all fittings, and fuel looks fine.

    It was misfiring @ idle intermittently this AM, so I checked all connections, plugs, wires, etc. (BTW pretty sure I got zapped a bit when I pulled the cowling). Idle smoothed out but still no top end.

    Any ideas?

    Thanks!
     
  2. Brett

    Brett > PRO STAFF <

    My troubleshooting routine from a previous post...


     

  3. Creek Runner

    Creek Runner Well-Known Member

    1,544
    21
    643
    What kind of motor? Year? Etc? Etc?
     
  4. richwalker71

    richwalker71 Well-Known Member

    294
    2
    391
    Sorry. 99 25hp Merc 2st.
     
  5. topnative2

    topnative2 Well-Known Member

    2,109
    267
    938
    since u got shocked,run the motor cowling off in the dark and look for fireworks
     
  6. Creek Runner

    Creek Runner Well-Known Member

    1,544
    21
    643
    If it skipping bad then it will more than likely be an ignition system; you should be able to tell visually and hear if the motor is skipping, but the RPM’s are getting pretty high to be an ignition problem. I would pull the carb cover off while running it put your hand over the crab for just a second, you are basically acting as a butterfly choke, since that motor doesn’t have a choke. If it picks up RPM’s you have a fuel issue not an ignition problem.
    However the 1st test before all other test should be a Compression test!!!!
     
  7. richwalker71

    richwalker71 Well-Known Member

    294
    2
    391
    Picking up a compression tester tomorrow. Thanks.
     
  8. DuckNut

    DuckNut Brandon, FL

    4,517
    400
    1,938
    .

    X2

    And if at first you don't see the fireworks - mist it with the garden hose and vary the rpm's. Gotta be dark - not dark outside and under the garage light.
     
  9. Creek Runner

    Creek Runner Well-Known Member

    1,544
    21
    643

    ^  [smiley=badidea.gif]  Okay I have bitten my tongue on previous post about running the motor at night; but I have to say this is not the correct way to diagnosis an engine. That is what some junk yard mechanic would do, NOT A MARINE TECHNICIAN; To the OP it is highly unlikely that you were shocked from the engine while pulling the cowling off, If there is something arcing it’s taking the easiest resistance to ground and I highly doubt your hand on the engine cowling would be the easiest path to ground unless your grab the ignition coil wire ( Not calling you a liar just saying that it's not likely), In 15 years of working on Marine engines I have never been shocked other then when I have touched the Ignition coil wire.

    The reason why I gave my previous suggestion was that it’s only a 25hp which means it’s a 2 cylinder and if you’re losing spark chances are you would never get to 3k rpm’s

    Here are the 1st couple of correct procedures to diagnosis all marine engines. You have 3 needs to make and engine run, Compression, Spark, and Fuel.

    1st Compression Check (Always 1st) any reputable Technician will always do a compression test 1st.

    2nd A Spark test (Running the engine at night is not how you do this or any other test I have ever been taught at Yamaha, Mercury, OMC, BMC, or Suzuki school)

    3Rd Fuel Test (Depending on the engine would determine how this is performed) 
    After these 3 steps have been performed and only AFTER can you move to other trouble shooting procedures.
     
  10. Brett

    Brett > PRO STAFF <

    Dang...all this time I thought it was redneck tech!   ;)


    For those of us without a shop full of proper tools, the night time/cowl off/spark spotting technique
    is a quick way to find cracked spark plug wires, loose connections, and improperly grounded components
    that otherwise would require real tools and the knowledge to operate said tools.

    It took me a few years and several boats before I got past that level of outboard electrical diagnosis.   :-[  ;D
     
  11. Creek Runner

    Creek Runner Well-Known Member

    1,544
    21
    643
    I can see your point of not having all the special tools and required skills to use them; However you don’t need any special tools to diagnosis a 1999 25hp Merc 2Stroke. And if you did a proper visual inspection of all wires, and checked all connections in the day time, you wouldn’t find anything at night that you wouldn’t know already.

    If I was working on the engine the only tools I would need is a screwdriver set, a socket, and wrench set.

    I just don’t see the purpose of doing it, I just feel it’s a 2nd rate way of doing something, and like you said it took you a couple of years to graduate up; well if people didn’t give bad advice and improper ways of doing things people could learn the correct way much faster.

    I’m a newbie around here and I’m not trying to make waves, but there are I know of at least 4 (Probably many more) including myself Marine Technicians on here that have the proper knowledge and skill set to give correct and proper advice. Instead of saying run your motor at night and look for the blue sparks, You could say visual inspect all wires for cracks in the insulation and make sure all grounds are tight. However you should still start off with the 1st 3 steps I said earlier ALWAYS, ALWAYS, ALWAYS. Until that is done you’re just guessing!!!
     
  12. Brett

    Brett > PRO STAFF <

    You ain't...in order to make waves around here, you'd have to be dissing gheenoes.  ;)

    All you've done is offer comments from the point of view of a trained professional
    dealing with barely competent amateurs. I've got no problem with that.
    I read all these diy posts, never know when I might have the same problem.
    Comments from a professional mechanic are especially valued.
    I was taught a long time ago: Never argue with a pro, listen instead, I might learn something.

                                                        [smiley=happy.gif]

                                                    
     
  13. richwalker71

    richwalker71 Well-Known Member

    294
    2
    391
    FWIW it was the control module.
     
  14. Frank_Sebastian

    Frank_Sebastian Well-Known Member

    787
    2
    391
    TRW I want to thank you very much for taking the time to report on what the problem was. So often we never hear back and wonder if it was our suggestion or someone elses that solved the problem.

    Best regards,
    Frank_S
     
  15. richwalker71

    richwalker71 Well-Known Member

    294
    2
    391
    No problem. After I had it figured out I looked at the troubleshooting guide in the manual. Right there in black and white it said "timing will not advance= faulty control module".
    Maybe I'll read more carefully next time!
     
Loading...
Similar Threads Forum Date
Ignition for Thunderbolt Merc. Outboard Maintenance Aug 25, 2017
Ignition works without killswitch engaged General Discussion Jun 30, 2014
SOLD/EXPIRED Honda outboard ignition switch harness and panel #37452-ZW7-110AH Sold/Expired Classifieds Jan 27, 2014
SOLD/EXPIRED Suzuki Remote Control Box (binnacle) and rigging/ignition for sale Sold/Expired Classifieds Sep 12, 2013
Yamaha OEM vs Sierra Ignition Switch Outboard Maintenance May 2, 2014