Mercruiser carb rebuild but hard start and idle

[MilleniumFalcon]

New float has been installed and additionally I had to tap some of the screws to a larger size on the bike due to them stripping out. I’m wondering if I didn’t have a vacuum leak as well. After all this I have gotten the boat to start great and idle like it should. I’m having to keep the idle mix screw almost all the way in for the smoothest idle. Should I be concerned with this?

 

[alldodge]

I’m having to keep the idle mix screw almost all the way in for the smoothest idle. Should I be concerned with this?

Almost all the way in is better then all the way out. The further in it goes the less fuel is needed to run. If the idle neelde screws and or seats are a bit damaged this can also cause issues. If the screws were run in tight then backed out this can damage them. It will still run, but just causes the screws to be further in to reduce the amount of fuel

In any case sounds like your doing better

 

[MilleniumFalcon]

After new float was installed and I had it firing great and idling on the trailer, I took it to the water. It was stalling out again just trying to get it to idle. As soon as I put it in gear it would die. Sitting on the trailer in the water in neutral, the boat was struggling to start. After messing with it for a bit I finally pulled it back out. It was showing some black smoke again and smelling of fuel. Should I set the float more aggressively then what the manufacturer recommends in this case? It sounds like it’s still getting too much fuel.

looks like a new carb is about $400. Would this be a fix all?

 

[alldodge]

showing some black smoke again and smelling of fuel.

I would adjust to float lower, your running rich and flooding the motor

 

[MilleniumFalcon]

Having to order brass float. The Sierra replacement was eaten up by gas...

 

[MilleniumFalcon]

It seems that a brass float is a lot harder to get than I anticipated but I see where Sierra lists their plastic float as alcohol resistant. I'm going to try another one and hopefully now that I have a better understanding of how the carb functions and how the float plays it's part, I can get some results. Thanks

 

[Silvertip]

Set the choke when the engine is stone cold. Setting it on a warm engine will result in an overly rich condition.

 

[MilleniumFalcon]

I have finally replaced the carburetor with a Sierra rebuild and had a buddy who’s a car mechanic look at it. Needed a new starter, had bad gas from sitting over the winter, and went ahead and got a new battery. Discovered the old carb had just been dumping gas into the motor and the oil was full of gas. Changed the oil along with the starter, battery, and gas. She fired right up after that! A slight adjustment on the throttle screw and were ready to go!

 

[alldodge]

Good to hear its going

Discovered the old carb had just been dumping gas into the motor and the oil was full of gas.

This is most likely from a bad diaphragm in the fuel pump. If it has a rupture, it will keep leaking fuel into the block. There should be a clear line going from a fitting on the fuel pump up to the carb. This line is there to show the pump is leaking

 

[dezmond]

AllDodge I like the clear line idea. I shall do the same