91 merc 135 carbs/floats

[Mike Caspari]

twin V-6 135's.when pumping my fuel bulbs they don't seem to get "hard". Is this due to floats sticking? Motors seem to run and idle ok but one studders a bit around the low end when accelerating. How difficult is the overhaul of the carbs, I've heard bad things but I consider myself to be somewhat mechanically inclined and I kinda enjoy a challenge.

 

[Laddies]

Re: 91 merc 135 carbs/floats

If the engine is running all right, chances are the reason the bulb are not getting hard the check valve in the bulbs are bad, sometimes you have to hold the bulb outlet up to get them to pump it depends on the manufacture. If you trim the engines under at idle it will richen the mixture and if you tilt them out it will lean the mixture see if it will get over the stumbling that way first--Bob// sorry but inreply to cleaning it's not a big deal

 

[Mike Caspari]

Re: 91 merc 135 carbs/floats

sounds like a plan. If you have the engine trimmed up slightly, take the carb cover off and then pump the bulb, should you get gas into the throat of the carb?

 

[Laddies]

Re: 91 merc 135 carbs/floats

Not unless you are building alot of pressure

 

[Mike Caspari]

Re: 91 merc 135 carbs/floats

Run seafoam through the motors and both sound great now but they still use gobs of gas. twin efi 225's get better mileage than these 135 carbed!!!!stuck float?

 

[MrBigStuff]

Re: 91 merc 135 carbs/floats

Mike, I have the same motor, same year on my bass boat. I rebuilt my carbs last year and it wasn't difficult at all. It was harder to find the parts than to do the work. Some yokel had put in viton tipped needles and they didn't have the retainer clips that connect them to the floats. Not suprisingly, they kept getting jammed in the seats and that's why I ended up rebuilding the carbs shortly after buying the boat.<br /><br />Anyway, my motor runs like yours and the bulb doesn't get hard either. I know the carbs are set up and working correctly so I assume it's the bulb. Cheapest to try so do that first.<br /><br />I just haven't had the time to adjust the carb mixtures and would prefer a rich motor to a lean one. Plugs are cheap.<br /><br />One thing a guy I work with mentioned is there may be some type of plastic plug in the engine behind the carbs, It's supposed to melt in the event of overheating and create a rich condition to save the motor. I didn't check this when I did the carbs and don't know if he's right or not. My motor was used and I don't know the history so if it was overheated at one point, I don't know. I bought the Seloc manual and haven't found any reference to this "plug" in there. I plan to adjust the mixtures and then dig deeper if necessary...