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Mercury 80 hp carb rebuild

Chip Whitworth

New member
Hello everyone.
I just rebuilt my carbs last weekend because i was out on the water and it would not start, ended up there was alot of junk in carbs. So i cleaned all fuel lines and drained fuel. Rebuilt carbs, now i can not tell if i have the carbs (2) set right. I have two videos of the engine running and rev'ing. This is my first old mercury so hopefully someone who knows these motors can give me some pointers on setting them up correctly.
http://www.youtube.com/watch?v=g4Lfl8KAfi8
http://www.youtube.com/watch?v=OEm90EOHd5A

IMG_06571.jpg

IMG_06621.jpg
 
Very fmiliar with that carb! When you "rebuilt it", if you didn't soak it overnight and blow out the passages in the fuel bowls you will have massive bog problems.

Test it by letting it high idle, then snapping open the carbs with your finger (on the lever at the top of the carbs). If it picks right up, you're okay on the idle mixture settings; if not, add an 1/8 th of a turn CCW.

Jeff
 
Great, when i rebuilt the carbs i ordered all the gaskets and needle valve stuff. I cleaned everything with carb cleaner (forgot which brand) then got the air compressor and blew about 150 psi through everything in the carbs. The pictures above where before i took them apart. I took alot just in-case i forgot where something went. Did you look at the videos? That silver screw on the right in pictures is turned about 2 1/4 turns out on each. I will try what you said and maybe take a video so you can just look at it.
 
Ah, but did you also blow out those tiny passages in the fuel bowl? That's where the problems with these carbs comes up. Any crud ends up down there to plug up that tiny orifice. Needing to open the idle screw that far out says something is restricting the flow.

Jeff

PS: I'm working on a 'fix' for that problem by enlarging the passages in the bowl. Gonna do one of them and see how it works out.
 
I took everything apart and blew the heck out of everything. What i will do is take a video with the carbs at 1 1/4 and then 1/4 incriments so you can hear it. By the way thanks for your input thus far, you have been very helpful.
 
Ok, i completed my carb build. It ran ok for a bit, then became hard to start, i have to give it half throttle to start, then when it starts, when i get it in gear it will go, but about half throttle it will bog down and die. I took off carbs today and checked the float and everything to make sure that they are shutting right, both are. I still had them connected to fuel lines but not mounted on block. I pumped the primer bulb and noticed that gas was coming out from where carb mounts onto block. What to do?
 
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