1982 25hp Mercury Mariner Carburetor rebuild help!!

[Mercury25hpower]

Hi I have a 1982 25hp Mercury Mariner 2 stroke, it's very hard to start, the spark plugs are good & the fuel mixture is at 50/1. when I try and pull start it there seems to be too much fuel dripping from the top left screw(opposite the idle control needle) & sometimes it backfires, I have fitted an online rebuild kit with new gaskets and seals, is there anything else I should look at regarding this engine/carburetor, any help would be much appreciated.

 

[flyingscott]

Your float level may be to high.

 

[Mercury25hpower]

Thanks for the reply flyingscott, I have cleaned the fuel bowl and float/inlet needle valve, it seems to be sitting level with the lower casing of the bowl, my experience with setting the float is minimal as this is my first ever boat engine, I've watched a few Youtube videos, can you tell me from the image below if there should be an O ring on this plastic screw, cause mine doesn't have one. reffering to No.20 on the carb diagram, could this be a problem!

 

[flyingscott]

What is your model #. There should be a fibre washer or o-ring on that to make a seal as that is your high speed jet. You may need to look at the flywheel key as it could be bent. Is this motor new to you.

 

[Mercury25hpower]

Thanks flyingscott much appreciated, Yes this motor is new to me, about a year ago I bought this engine with boat and it was flying it for about 3 months and all of a sudden it got very undependable, cutting out and hard to get started, model number on the Carb is BC1B 105

 

[flyingscott]

Need the model# of the motor. And before you go any farther do a compression and spark test and look at the reed valves see if any are broken. Did this motor overheat by chance?

 

[Mercury25hpower]

Sorry for the delay flyingscott, this engine never overheated on my watch as I've always had it on the water or in a water barrel when starting it, see the image below for the engine details, I will do a compression test/check the reed valves in the next few days, thanks for the reply.

 

[w2much]

Why the last photo. ? Did I miss something ?Your motor is a 1982 25HP Mercury. Photo is 1996 Merc 25HP

 

[flyingscott]

If that is your motor, put up a pic of the carburetor because 96 and 82 are very different carbs.

 

[flyingscott]

sorry about that i meant Put up a pic of the motor itself.