rochester 2 brl on 3.8 running too rich?

m_87 · Jul 12, 2010

here i have a 1983 checkmate omc i/o has a 3.8 GMC engine took it out last weekend with a fresh carb rebuild its runnign rich it idles great and when not in gear it will rev great seams awesome other than it smelling rich of gas (or when in gear) . i noticed that at the top of the barrels which i balieve are the brethers for the float capartment there was gas kinda coming out of them when it was reved. so i was thinking i need to adjust the float? any ideas? just didnt want to be barking up the wrong tree. verry fresh to the carb thing

Howard Sterndrive · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

all it takes is a piece of debris to cause the needle and seat to leak - the float cant close them and you over fuel at idle, or could be the adjustment

also watch the yellowish line from the fuel pump to the carb - it should not be flowing any fuel. If it is, the fuel pump diaphragm has ruptured

m_87 · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

i just rebuilt it so its clean as it will ever be. we took the top off and checked to make sure the float was working poperly and it shut off the fuel when it needed and seamed ok. it will idle all day and the only time i notced that it will leak the fuel out of the breather holes was at higher RPM's and when i push the RPM's it bogs and wont ever get back under itself. it did have a bad fuel pump but i also replaced that befor the carb rebuild along with the fuel lines. thanks for the input anymore would be greatly appriciated.

Bondo · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

Ayuh,... It sounds like ya screwed up the carb rebuild...

m_87 · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

i dont think so...

hope not. what would cause that tho? i am not around the boat right not otherwise i would probably be taking another look at all the ports

Bondo · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

Ayuh,... Float levels,..??
Missed Crud,..??
Donno... Any of the settings are suspect...

m_87 · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

i think your right on the float level i think its just getting too much gas in the float bowl befor it shuts off gas supply. will do some research on that.

m_87 · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

FORGOTT to mention. befor i did the rebuild it had similar symptoms but wouldnt idle just sounded like had water and gunk in the carb.

Bondo · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

Ayuh,... You're fighting a fuel delivery issue,... It seems to be the Carb,...
But,...
Everything from the tank vent to the carb should be Suspect...

Another thought,....
You've got a 27 Year old carb, that may have had water in it for who knows how long....
I'd give a Rebuild, aka. Backyard/ shadetree, a 50/50 shot at Success....
Just sayin',....

m_87 · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

great idea... but would that be causing it to run rich? like i said the breather holes (corrent me if you think i am wrong) thay are located at the top of the barrels have a small amount of gas seaping out when reved. i know its not the carb gas pump or fuel advance thats (seaping) ..

also i know thae fuel pump is working great checked it and its not starving the carb or over pumping it. i dont see how the gas tank would be staved for air if the breather holes in the carb are seaping gas. i know there is a functioning gas breather for the tank as it spit a little fuel when i filled the boat. but i will for sure look thought all that again.

so im back to the float level. might be off...

Silvertip · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

The "breathers" as you call them are not "breathers". They are venturies that draw fuel into the air stream as the throttle plates open. Some carbs have a check ball in the bottom of the accelerator pump chamber and some do not. If that ball (about the size of a BB is missing fuel will dump out the single tube in the upper center of the carb. High or misadjusted float as pointed out, will cause the problem you have as well. You rebuilt the carb for a reason -- what was it?? you may also have a float that has become porous and fuel soaked which means it does not "float" properly so even if the rise and drop dimensions are correct, it won't float at the correct level. Did you replace the float?

Howard Sterndrive · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

original fuel pump?

I ask because needle/seat can only hold back about 5-7 psi

m_87 · Jul 13, 2010

Re: rochester 2 brl on 3.8 running too rich?

great thoughts guys the bb sized ball was observed and put back during the rebuild. there were actually two of them one under the pump and one elswhere. i will check out the float but i dont remember it having any fuel in it and i am about 75% sure i would have.. about 40% on the fuel pump being original. but i did purhas it at autozone just told them i need a mechanical fuel pump for a gm 3.8 and thats waht they gave me. it was a little different but but i figured it was just a replacement that did all the same. i checked the pressure that it was putting out just with my finger and didnt have a ton. will get a gage and check it with that. thanks allot everyone for the imput.

m_87 · Jul 13, 2010