3.0 L Merc stalling out

hello, i have a 2006 3.0 liter mercury engine that is stalling out. Now I just pulled the boat out the storage and i tired to start it up, it took a couple if seconds and fired up but it had really rough idle and it did not get better as it warmed up (it sounded like a diesel engine) so i shut it off and took the carb out to clean it then bolted it back in and fired up (again it took a couple of seconds but quicker then before) it fired up and it still had a rough idle but not as bad as before. it eventually smoothed out and when i gave it gas (about 2000 rpm) it wouldn't idle after that. to fire it up again i had to press my throttle all the way down and back up which adds more gas and it fired up for a few sec then died. The only way it would stay running if it was above 3000 rpm. This happened last year but not as bad, once i got it out on the water it ran fine and only stalled a couple of times but fired up again. Now i am thinking about taking it to a mechanic to get it tuned up but i just want to see if you guys have any suggestions on what could be the problem before i spend money at a mechanic. Oh and i forgot to mention that all of my problems are happening on the ground.

Thanks

Re: 3.0 L Merc stalling out

Welcome aboard

Need to know what kind of maintenance it has had. You should have

Replace fuel filter
Check engine alignment
Check plugs, cap and rotor
If gas quality is suspect (I would suspect from what I'm seeing) use a portable fuel can and connect to engines pump. Run engine and see if it clears up

Re: 3.0 L Merc stalling out

ok well i used fuel stabilizer before i stored it and i did add about 3/8 of fresh gas to it before i started it. I did clean the spark plugs before i stored it but i will definitely look at them and clean them tomorrow, as with the cap and rotor (which i never checked). I did not change the fuel filter yet ( it has been about two to three years) so i am going to have to replace that this weekend also. And i have never done an engine alignment or what it even means.

Thanks

Re: 3.0 L Merc stalling out

Mentioned you took the carb off and cleaned, was that total disassembly and clean or something else? Change the fuel filter add some fresh gas to it before you reinstall; this way when it starts up and if it runs great for a bit then starts running crappy we know its the gas.

Re: 3.0 L Merc stalling out

AllDodge said:

Mentioned you took the carb off and cleaned, was that total disassembly and clean or something else? Change the fuel filter add some fresh gas to it before you reinstall; this way when it starts up and if it runs great for a bit then starts running crappy we know its the gas.

Click to expand...

Also might try spraying some carb cleaner or unlit propane torch around the base of the carb when you fire it up and see if you have got a vac leak.

Re: 3.0 L Merc stalling out

well i wanted to completely take the carb apart but one screw was really stuck and it started to round so i stopped and just sprayed all the parts i could with high pressure brake cleaner, now would i be able to siphon the gas out through the filling port (or what you call it) or would there be like a mesh or something to block the hose from getting to the actual gas tank (kinda like a car).

Re: 3.0 L Merc stalling out

i also got a new gasket that i forgot to mention for the carb base

Re: 3.0 L Merc stalling out

Seems to me like you need to clean out the idle jets. You need to blow out all the jets and passages. Physically remove the jets and clean them. Replace gaskets with new ones, don't re-use.
I wouldn't worry about engine alignment as suggested earlier.

Re: 3.0 L Merc stalling out

well the problem is that i cannot completely separate the carb because one screw is really seized and i started to round it, i did clean everything that i could but i could not physically remove the jets to clean them

Re: 3.0 L Merc stalling out

If you can't clean out the idle circuit, then you haven't done much. That's where the issue is.....in my opinion. The jet has to come out, or you will never get it cleaned.