81/82 Merc 18 hp fuel carb trouble

[eclipseturbors]

I got this Merc with a boat that I traded for. It starts on the first pull and has nice spark on both cylinders. I have a few questions. With the choke turned all the way clockwise, the motor will idle rough, but will not die. I see that an arm pushes down a small valve that I assume is maybe a cold start circut? When I start moving the choke back counter-clockwise a click or two, it starts to rev up. When the choke is open, it starts popping back through the carb and dies. I know that the mix in the tank has about a gallon of 40:1 mixed with about 5 gallons of 50:1 from a marina. I'm now seeing a little milky colored fuel coming back through the throat of the carb and there is aparently a small nipple that is missing a hose at the bottom of the carb that is also leaking fuel out. I was hoping that the idle trouble would start to clear up with a treatment of Sea foam, but I'm doubtful. The only other information I have about this whole ordeal, is that we took it to the lake to give it a test run, and the fuel pump diaphram plastic inlet broke and was leaking too bad to repair at the lake. It's been replaced along with a new seal. If this is a carb rebuild situation, is this something I need to try to get a service manual for, or can I just replace the parts and clean her up? Sorry for the long post, but I know it's helpful to have as much info as possible in my line of work when it comes to internet boards. Thanks to anyone who can help...

 

[jimmyzshack]

Re: 81/82 Merc 18 hp fuel carb trouble

Does it have "BC" stamped on the carb? I believe the 18 and the 25 use the same carb for that year. There is a rebuild kit but it doesn't come with the inlet needle. I need the inlet needle to fix mine. You can no longer order it or the whole carb itself i'm looking for a used carb now. Just an FYI.

If the carb has "wm" stamped on it you should be able to get parts.

http://www.maxrules.com/fixmercurycarbkits.html

 

[eclipseturbors]

Re: 81/82 Merc 18 hp fuel carb trouble

I was able to get parts locally from an older boat place pretty easily. My problem is that I think that the bracket that holds all the linkages may be bent??? I replaced both bleeder hoses and noticed that the bracket looks kind of funny. Does anybody know if this is right or is there supposed to be some spacers in there?

 

[eclipseturbors]

Re: How fast on 18hp?

Re: How fast on 18hp?

Well, long story short. The motor ran like crap in a barrel, but pretty good at the lake. I had my father in-law pace the boat with his PWC with my wife and I at 25 mph. The boat is an older 14ft Lowe. I built a jack plate to raise the motor to about the right height. It seems to porpoise alot if the wife sits in the middle bench. The boat takes a bit to plane with just me in it. Oh yeah, I'm 230lbs. Does this sound about right? The prop has seen better days and I'm wondering if I should just get this one refurbished or buy something else?