1988 60HP Mercury - No Idle

Discussion in 'Bubba's Outboards' started by turtle1173, Jun 3, 2007.

  1. turtle1173

    turtle1173 New Member

    Messages:
    611
    State:
    Mayfield, KY
    Well the motor was doing great until 2 weeks ago. My Dad came down to visit and we headed out to the river. Everything was fine on our trip until the last couple of spots. I started throttling down as we were getting to our spot and preparing to anchor. As I throttled down, it just died. It never does that. I could restart it with the warm up lever up more than usual but if I just moved the lever down, it would die. As long as I put it in gear before it idled all the way down, it would go.

    I got home & checked the compression. 112-118 on all 3 cylinders.

    I hadn't taken the boat out in a couple weeks but took it out again yesterday. The only difference between yesterday and 2 weeks ago was that occassionally I could throttle it down slowly and it would idle for maybe 10-15 seconds, then abruptly die.

    I was thinking maybe a float was stuck or something like that. Today after church, I removed the carbs, opened them up and everything looks good & clean inside. Float moves freely and so does the needle valve. Although I haven't taken the needle seat out yet. When I removed the carbs, I noticed the coupling assembly broken. I don't know if I broke it taking the carbs off or if it was already broke. For those who don't know what that is, that's the part that connects the top carb to the bottom carb (this is a 3 cylinder, 2 carb motor). If this was getting weak, that would throw off the synch of the carbs. I don't know if that would have just happened all of a sudden though. Anyway, I've got at least that part to replace.

    Any other ideas?

    Thanks a lot!
     
  2. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    I've broken that connector before on Mark J's motor. Same engine, but with a Mariner name.

    You need to check your spark at cranking speed. There's a two stage stator in them. Produces spark at low speed them starts to take over nearing 2000 rpm's for high speed.

    Low speed side could be going out. This is only a suggestion. Not saying it's an absolute fix.

    You need to do an ignition output test to be sure.
     

  3. turtle1173

    turtle1173 New Member

    Messages:
    611
    State:
    Mayfield, KY
    Hi Bob,

    I think you've nailed it on the head. Let me tell you what I've checked, then let me know if this sounds like what you're talking about.

    I got my carbs put back together this afternoon with a new coupling assembly. I decided to take it down to the ramp and see if I could isolate my problem.

    What the motor is doing is coughing or popping real bad at lower rpm's. I believe what it's doing (and I think this is what you were talking about in your post) is momentarily losing a cylinder. When I idle it down, it will "pop" and die. When the neutral warm-up lever is raised, you can hear it popping here and there but it is much more pronounced at the lower settings.

    I wanted to do a test to figure out which cylinder was losing spark (although I don't know if it's relavent here or not). I did the standard "check for spark while cranking" test with a spark tester and it showed spark on each cylinder. I couldn't really tell which seemed stronger. My next step was that I wanted to remove a plug wire while the engine was running but I was really nervous about doing this. I got zapped a few years back and I'll tell you... it hurt, LOL :roll_eyes: So I chickened out. I did the next best thing (in my mind anyway). I got the motor running at idle at a level where it was popping some but running fine. I would then shut down the motor, pull off one of the plug wire, and then try to start the motor right back.

    Here's what I found:

    When #1 was unhooked, the motor started and ran just like it did before unhooking it.

    When #2 was unhooked, the motor started and ran very rough. It was laboring to stay running and also popping but it never died that way.

    When #3 was unhooked, the motor would not start at all.

    So by this test, it seems to me, I've got good spark on #3, intermittent on #2 and bad on #1. They all are getting some spark (as proved by the cranking test) but it is strongest at the bottom.

    Perhaps this all is related to what you said but maybe not :roll_eyes: Does this sound like it is my stator going bad (at least the low side)? What else do I need to check/do?

    Thanks a bunch.
     
  4. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    I'm thinking your stator's fine and it's in your carburation. I need to do some more checking on those dandged two carb, 3 cyl motors.

    Got a similar issue with Mark's, but I need to get it to the water to be sure.

    Those carbs are finicky little rascals, Need to be set just right.

    You wouldn't have any fire to your power pack if the stator was bad on the low side.

    I'll do some more checking and get back when I get a chance.
     
  5. turtle1173

    turtle1173 New Member

    Messages:
    611
    State:
    Mayfield, KY
    Hi Bob,

    Well after your response I was thinking, if it's in the carburation then that popping must be from a lean condition. So I headed back out to the ramp this morning. Glad I wasn't launching out because the winds howling at 30+ mph today.

    I had quite a "stupid moment" first off. I couldn't get the motor started. This was real frustrating. Finally I could tell the battery was running down. As last resort I put a little premix in a container and put it in the carb throats. It fired over and started. "Whew" I thought. I let it warm up for a little bit before trying to idle it down some, so I could mess with my idle mixture. My manual has the initial setting for one turn out from lightly seated, which is what I had it set at yesterday. So I set it at 1 1/2 out. But I still couldn't get it to idle down without dying. I tried to get it to go in gear and it would just die. Finally I was at my wits end and decided to call it quits. I pulled the boat out and went to the back to put the cowling back on. That's when I noticed that the #3 plug wire was still disconnected from yesterday!! What a dummy!!:embarassed:

    Driven by a new found motivation, I backed her down AGAIN. The battery still wasn't charged yet, so I had trouble starting again. Using the same way method I did previously and she fired up. Wow, it sounded better, LOL. This time she idled down all the way (Hurray). Shifted into gear nicely. She gave me a nice slow idle in gear. No hesitation when I hit the throttle. Everything was good.

    The only thing that bothers me is that I can't replicate my problem yesterday. I ran it at idle in gear and turned the mixture screws back to 1 turn out. It didn't sound as good but it never did POP at all, let alone like yesterday. I don't understand.

    Any thoughts??

    Thanks again!
     
  6. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Understand? Hell no!:tounge_out:

    If it's running good, be happy. Sometimes it's just a gremlin you can't put your finger on.

    If making one carb richer than the other works, than do it. The starting point is just that, the starting point.:confused2:

    There's times I complicate a problem with too much thought and it's just something basic that's overlooked.:roll_eyes: