87 Mercury Classic 50 won't throttle past 3000 RPM?

Discussion in 'Bubba's Outboards' started by achilles555, May 11, 2009.

  1. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    Bought a 1987 Bass Tracker with an '87 45 HP Mercury on it. Floats were stuck, so I had to have both carbs rebuilt. Took it out for the first time this evening. Went right up on plane, and I was running 5,000 RPM at WOT (about 30 MPH). All of a sudden, the motor bogged down, and died. Started right back up, but now won't throttle past 3,000 RPM in gear and won't plane out. In neutral, it is fine...throttles right up.

    I pulled all the plugs and looked at them when I got home. The only one that was dry was the bottom one. Other 3 were wet w/ fuel and had a little black sludge pooled in them. Hard to really tell because the plugs are brand new. One other thing...my 6 gallon tank only had about 1/2 gallon of gas left in it. I was only out for about 1 hour, and 30 minutes of that was idling back to the ramp. Seems like it's pulling a lot of gas. Also, the bulb was soft when I got it home.

    Photos of my plugs can be seen at the following addresses:

    http://www.flickr.com/photos/24479981@N03/3523583153/in/photostream/

    http://www.flickr.com/photos/24479981@N03/3524390450/in/photostream/

    http://www.flickr.com/photos/24479981@N03/3524390280/in/photostream/


    Can you guys tell me anything from these photos? What is going on with this motor? Thanks somuch for the help. Not sure what I would do without the advice you guys give on these forums. AC.
     
  2. macdaddy

    macdaddy New Member

    Messages:
    687
    State:
    GEORGIA
    check for water in fuel
     

  3. dieselcat

    dieselcat New Member

    Messages:
    406
    State:
    Washington, Mis
    do a compression check and all cylinders should be within 10% of each other,so if you get lets say,125,125,125,and 115 then your probibly ok.but if you get 125,125,125,95 then you got a problem and should try a decarb to bring the 1 odd cylinder up.BTW you shpould have at least 100 PSI on all cylinders or the motor may not run right.
     
  4. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Number 4 isn't fireing. Check all the coils and grounds. They have to be ib good contact to work right. When you rebuilt the carbs did he change all the rubber lines and check the fuel pump also.
     
  5. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    thanks for the reply gentleman. when i had the carbs rebuilt, he didn't replace any of the fuel lines or rebuild the fuel pump. sounds like i now have a saturday project for myself.

    i did buy a new merc supply line and tank when i bought the boat, so i should be good there.

    bubbakat - is it possible one of the diaphrams or something let loose in the fuel pump and is clogging a jet on the carb? i really don't want to rebuild those carbs again.

    one other question bubbakat. why do you say #4 isn't firing? thanks again for the help. ac.
     
  6. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    i had a guy at the marina suggest to me that it could be my stator. does my motor have a high and low side stator, and does this sound like it could be a stator problem? thanks, ac.
     
  7. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    #4 is to clean for a surface gap plug to be fireing. Only two things will clean one that clean and thats a head squirting water on it or its not firing. I will look through my old manuals and find the test for the stator. Yes a stator can stop one from firing on one or two or all. Cylinders. We can test the stator and the other stuff except but not the switch box. There is no test for that. Now go get you a good ohm meter and a good spark tester and tomorrow I'll post the test for you to do.
     
  8. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    bubbakat - did i ever tell you how much i appreciate your help? well i do! came home tonight and tested compression and spark on all 4 cylinders. couldn't wait...as most people probably understand, it's eating at me. well, compression is good on all 4 - 120 psi. i have a strong spark on all 4 cylinders. tested them with a good gap tester. guess it's down to a fuel problem or the stator. stator is $350...so hoping it's not that.

    how often do stators go bad?

    i look forward to your post bubba. until then, i'll be sitting here scratching my head. ac.
     
  9. macdaddy

    macdaddy New Member

    Messages:
    687
    State:
    GEORGIA
    i HAVE SEEN A FEW BAD ONES ON force MOTORS
     
  10. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Stator Test.----Disconnect the 2 yellow wires from the recetfier. These will be coming from under the flywheel down to the recetfier. Take tem loose from the recetfier and set your ohm meter on RX100 and test the leads seperate with the red lead from the meter to one of the yellow wires. The black probe to ground and the meter should read at .75 ohms. Test both yellow wires this way and if out of scale then most likely is bad.
    If you don't have a book I highly recommend you spend the 30 bucks and buy one. You have a trigger under the stator that can be tested also but I need to know the color of the wires to get the right ohm numbers. They should be black and blue ore red and blue or blue and white.
     
  11. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    OK Bubbakat. I did the stator test that you recommended, and I got NO continuity between either yellow wires. I did, however, do some other testing, and I need help deciphering these readings. I also found a corroded and crumbled wire that had the copper exposed (it is the black/white wire coming from the trigger). I have added photos to the bottom of this post for you guys to have a look. Here are my test results:

    Stator Test:
    • Rx1 - (+)yellow to (-)yellow: resistance less than 1 ohm (good)

    • Rx1 - (+)yellow to (-)engine ground: no reading (good)

    SO FAR SO GOOD - HERE COMES THE TROUBLE

    • Rx1000 - (+)Blue to (-)White: resistance =15 (should be in the range of 5.7 - 8.0)

    • Rx1 - (+)red to (-)red/white: resistance =180 (should be in the range of 56-76)

    • Rx1000 - (+)Blue to (-)Powerhead Ground: No Reading (good)

    • Rx1000 - (+)Red to (-)Powerhead Ground: No Reading (good)

    Rectifier Test:
    All tests were good. Rx1000 - All continuity was where it was supposed to be reading at 16 and 11 ohms. No continuity was also where it was supposed to be.

    Now, based on those Stator readings...am I in need of a new Stator? The White/Black wire coming from my trigger that is corroded, could that be throwing off my ohm readings from my stator? What is the purpose of that white/black wire from the trigger, and can it be fixed without replacing the whole trigger. Here are the pictures of that white/black wire:

    http://i286.photobucket.com/albums/ll117/acleme1/white_black2.jpg
    http://i286.photobucket.com/albums/ll117/acleme1/white_black1.jpg

    If someone out there could help me navigate these problems, I would sure appreciate it! Thanks so much, AC.
     
  12. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    This line should read:
    • Rx1000 - (+)Blue to (-)Blue/White: resistance =15 (should be in the range of 5.7 - 8.0)