Mercruiser Rochester 120 Carb Mystery?

[ntheyer]

I was boating today just like any other day without a problem. I pulled the boat into a slip and left it for about half an hour. I came back to the boat and started cranking to no avail. I pulled the spark arrestor off and noticed fuel gushing out of the top of the carb though a hole in the carb by the chock plate. While cranking it would literally pour out of this hole down the throat of the carb. I couldn't get the boat started because it was way too rich and ended up paddling and bringing the truck and trailer over and pulling it out. I pulled the carb and looked underneath the top of the carb. I see where the hole goes through, but nothing is there to pump fuel out this hole??? What the heck happened here?<br />

 

[Phantom17]

Re: Mercruiser Rochester 120 Carb Mystery?

try www.dougrussell.com and get the diagram of your carb. I'd be a bit nervous about what might have went down into the manifold, if in fact some part broke loose and fell in. I have a GM Rochester carb (1981) so if you have a question I have the manual for it. It's a 2 bbl on a 120 OMC GM engne, 400 OD

 

[Don S]

Re: Mercruiser Rochester 120 Carb Mystery?

That is the normal place for the fuel to go when the needle valve sticks open or the float fills with fuel, or really anything that can cause the bowl in the carb to overfill. You didn't loose any parts.<br />It will dump fuel into the carb like that till the fuel pump pressure bleeds off, and will start again when you crank the engine.

 

[Mahoney]

Re: Mercruiser Rochester 120 Carb Mystery?

you will need to take the airhorn off and take a look at the float assembly and power piston assembly. I am guessing your float is cought up or the power piston is stuck in the up p[ossition, when you crank the engine the fuel just pumps on into the carb with no check.