Mercruiser 3.0 runs really rich

[boatlessinca]

My buddy was having problems with his 3.0. It was really hard to start after it warmed up. I could tell that it was getting way too much fuel. I could smell gas. I opened the engine cover with the engine off and I noticed an almost clear, 1/4" hose that comes from the fuel pump. It attaches to a barb fitting at the top near the opening of the carb. Well, the first thing I noticed was air bubbles and fuel going up to the carb. Remember, the engine was off. So I took the air filter/flame arrester off and I could see raw gas in the top portion of the carb. I unhooked the hose and pinched it off and the engine would start and run fine.I noticed that the hose was kind of stuffed between a cooling hose and a metal bracket. Both were really warm so I moved the hose and hooked it back up to the barb fitting on the carb and it ran great for a while. I figured that the hose was getting hot and creating pressure and forcing unneeded fuel to the carb. But, after a half hour or so of running it started to do the same thing.So I took the hose and put it on the stud for the air cleaner to plug it off and we finished our boating for the day like that. So, my question is, what is that hose for and why does it want to send excess fuel to the carb?

Thanks in advance for any help.

 

[jimbo_jwc]

That hose dumps fuel that when a diaphragm ruptures on your mechanical pump is sent into carb to be burn't instead of leaking into block and diluting your oil for safety reasons it's clear so you have a visual indication .

 

[fishrdan]

The fuel pump is bad and needs to be replaced.

The clear hose that had fuel in it is the "sight tube" and is there for the sole purpose of letting you know the fuel pump has gone bad,,, (or the fuel pump's diaphragm has ruptured).

I would also change the engine oil and filter as the oil could be contaminated with gas.

 

[boatlessinca]

The fuel pump is bad and needs to be replaced.

The clear hose that had fuel in it is the "sight tube" and is there for the sole purpose of letting you know the fuel pump has gone bad,,, (or the fuel pump's diaphragm has ruptured).

I would also change the engine oil and filter as the oil could be contaminated with gas.

Thanks you guys. I had a feeling it was something like that. I will tell my buddy that he needs a new fuel pump. That should be something that we can do ourselves I think.
BTW I see that you have 01 superhawk 1800. I bought the same boat back in 01. Wish I still had it. Mine was green. My family and I had alot of good times on that boat!

 

[boatlessinca]

Is the fuel pump hard to change out? I haven't looked at it since the original post, but my friend,against my advice, is still taking the boat out. I told him to get a new pump and I would help him change it. From memory, it seems like it is easily accesible. What is it a 2 or 3 bolts and a fuel line?

 

[fishrdan]

So I took the hose and put it on the stud for the air cleaner to plug it off and we finished our boating for the day like that.

That's a really bad idea right there as the fuel inside that hose doesn't have any place to go, and if it does go somewhere, it's going to dribble fuel all over the carb/flame arrestor and fill the engine compartment with gas fumes, and if there is one little spark in the engine compartment........

Seriously, people die every year in boat explosions due to fuel leaks...

It's better to have raw fuel dumping into the engine, being burned by the engine and making it run like crap, than to have the fuel/fumes outside the engine.

Also, there is a possibility that raw fuel is being pumped into the engine's crankcase, diluting the engine oil. I seriously doubt gas is a very good lubricant, so he could blow the engine, scored cylinders, galled bearings.

Is the fuel pump hard to change out?...What is it a 2 or 3 bolts and a fuel line?

2 bolts, 1 rubber line and 1 steel line,,, an hour of work and $100-150 for a "marine" fuel pump.

Sorry to sound harsh, but that boat shouldn't be on the water until the fuel pump is replaced.....

 

[boatlessinca]

I agree with your last sentence. Hence I haven't been on the boat since my fist post. Thanks for the help. I'm gonna hound his ass to fix it.