Carbs - Maxum Boat Owners Club

Emilio · 10-21-2019, 01:23 AM

I have 5.7 merc with alpha 2 outdrives and carbs can anyone advise me on the jetting for the carbs my port engine appears to be running very rich with unburnt fuel being emitted any suggestions greatly appreciated thanks

mmwjr · 10-21-2019, 02:14 AM

2 or 4 bbl? If the starboard engine is running ok the port should be jetted the same. Are you sure it’s a jetting issue and not something else wrong with the carb?

Emilio · 10-21-2019, 02:22 AM

2 barrel both run really well thats what i cant understand the person i bought the boat from said that he had both carbs rebuilt run great but port smokes a lot (black) with unburnt fuel do u have any thoughts on cause or what i should be exploring thanks again

Emilio · 10-21-2019, 02:23 AM

Any suggestions to explore will be appreciated

jrsick · 10-21-2019, 02:27 AM

I'd first recommend that you download manual #24 from documents section. Some good info on carburetor checks and jet sizes. Also see page 1C-10 for causes of rich conditions.
You may be getting too much fuel, or, too little air.

Emilio · 10-21-2019, 02:29 AM

I will check that out thanks

mmwjr · 10-21-2019, 12:30 PM

Quote:

Originally Posted by jrsick

I'd first recommend that you download manual #24 from documents section. Some good info on carburetor checks and jet sizes. Also see page 1C-10 for causes of rich conditions.
You may be getting too much fuel, or, too little air.

Yup jr has got you covered on this. First thing to look at is the choke to verify its opening.

jparsons121 · 10-21-2019, 12:33 PM

I had a rich condition like this with my Mercarb 2bbl

Turns out I had a bad float which wasn't regulating the fuel into the bowl properly and excess was dribbling into the carb from the vent.

This was after a rebuild and changing to the brass floats. Turns out it had a pinhole in it. Improper setting of the float levels would also do this.

Found this by taking off the spark arrestor and with engine idling, looking down the carb throat. Saw fuel bubbling out the vent tube.

John

mrt214 · 10-25-2019, 12:12 AM

The jets are non adjustable. Are you referring to the needle valves? if you are the needles should be turned in all the way ( do not overtighten) until it seats and then turned back out 1 and 1/4 turns. These will adjust the air mixture which will resolve rich burning fuel . Make sure the choke is opening all the way. And yes what john said about the float.