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  1. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Yes, those are the colors. I originally posted the title as an 85 hp and then mentioned in a follow-up post that it is actually a 75 hp. IT IS A 1985 75hp, 4 Cyl, MERCURY, S/N 6615200 I purchased the boat a year ago, and have not seen any signs of a overheat buzzer, or wiring anywhere on the...
  2. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks for your input racerone. I do not have an overheat buzzer. Cylinder pressure is 140 on all 4 cylinders. I think I have tried simple troubleshooting...but I'm certainly open for something I have not tried.
  3. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    I'm still trying to resolve my plaguing (bogs down after 20 minutes...every time issue). Since my last time in the water last Fall, the carbs were rebuilt and adjusted. I also found a leak around the fuel pump diaphragm. Not sure if this will resolve my issue or not. But while I'm waiting for...
  4. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Yes, on the impeller and the fuel pump. Not sure what you mean about water leaking into the cylinders?
  5. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks. You probably didn’t read my original post. Tank vent was one of the first things to eliminate. But again. Thanks!
  6. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    I pulled out the carbs and removed the floats. They are not plastic, more like foam. I also tried your float test. They do float and didn’t seem to get saturated. Although, they don’t necessarily sit on top of the fuel. I’ll replace them anyway. I guess I was hoping one of them would be...
  7. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Hmm! Maybe it will make more sense when I get to the bowl and see the float. Thanks!
  8. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    BTW: I’m trying to think through why or how one of the floats is getting heavy and how the motor would be running great for the first 15-20 minutes before it starts to bog.
  9. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks! I will be gigging into the carbs soon. It's new territory for me :)
  10. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks a lot. I was feeling a bit intimidated about working on the the carbs...
  11. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Well, I believe it is a fuel issue. I took it out again today. When it bogged down again after roughly 15-20 minutes of running great at 3/4 throttle, I **** it down and removed all cowling to include the cover that exposes the two carb venturis. I then started it back up thinking I would spray...
  12. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Yes, new. New stator, trigger, CDI Switch Unit, coils, and spark plugs.
  13. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks racerone. I have tried another tank and fuel. And don’t have the timing light yet. I’ll pick one up soon, if I am confident I don’t still have a fuel issue. My wiring looks good. Texasmark: Do you feel it is still necessary to shoot sea foam into carbs if my motor is slowing down when I...
  14. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Ok. If that is the case-it slows down-is there any further need to do a spray shot into the carbs test?
  15. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks for the troubleshooting steps! One question concerning the immediate response that you mentioned when spraying into carbs. Any type of response would indicate a fuel issue?would a normal response be that nothing happens? I had a mechanic tell me that when it bogs to push in my electric...
  16. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Thanks. I’ll have to look into getting a timing light.
  17. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Yes, I changed the plugs. Same results. Thanks!
  18. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Turns out that Limp Mode is not a design feature with my 1985 Merc. Does anyone have any other suggestions for me? Thanks!
  19. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    BTW: Its a 75hp motor, not a 85 as my post title reads...Can't find an EDIT option.
  20. M

    1985 Mercury 85hp (4 cyl) runs great for 20 minutes then boggs down

    Texasmark, Thanks so much for your reply. I REALLY appreciate the help! I think the Ignition Switch that you are referencing is one of the parts that I did replace. I may not have the correct nomenclature. If it's the same...I heard it called The Switch Box, or CDI Box. The one I purchased was...
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