Mercury 50 dies, got me stumped

[BoteBoy]

Hey guys, new to the forum, been poking around for a while but just signed up. Got a problem I can't seem to solve on my own.

Recently got a pontoon boat that was probably a bit neglected, here's what I got.

It looks like fuel sat in the carbs for a while, it would barely idle and would not push the boat more than a couple mph. I cleaned the carbs and and checked the fuel filter. Now it idles great and will push the boat at a medium pace but as soon as you gun it or ease on the throttle past half it dies.

Plugs are new, fuel spits out when I disconnect the line and crank the engine. Tried turning the mixture screws a little bit in either direction but both ways seem to make it worse.

The engine is a 2004, any ideas what it could be? Maybe I didn't get the carbs clean enough?

Thanks in advance,

-Rob

 

[j_martin]

Re: Mercury 50 dies, got me stumped

Hey guys, new to the forum, been poking around for a while but just signed up. Got a problem I can't seem to solve on my own.

Recently got a pontoon boat that was probably a bit neglected, here's what I got.

It looks like fuel sat in the carbs for a while, it would barely idle and would not push the boat more than a couple mph. I cleaned the carbs and and checked the fuel filter. Now it idles great and will push the boat at a medium pace but as soon as you gun it or ease on the throttle past half it dies.

Plugs are new, fuel spits out when I disconnect the line and crank the engine. Tried turning the mixture screws a little bit in either direction but both ways seem to make it worse.

The engine is a 2004, any ideas what it could be? Maybe I didn't get the carbs clean enough?

Thanks in advance,

-Rob

How about the rest of the fuel system. Dirty, sludge in tank, hoses decomposing inside, plugged filter?

 

[BoteBoy]

Re: Mercury 50 dies, got me stumped

Checked the inside of the tank and it looked clean also replaced the fuel filter. If it were dirty or plugged fuel lines wouldn't the engine still run a full throttle until the carb bowls were emptied?

-Rob

 

[Silvertip]

Re: Mercury 50 dies, got me stumped

Are you certain it's running on all cylinders. Many folks have no idea how many cylinders their engine has or how to tell if they are firing. Generally though, bogging is almost always a fuel delivery issue. Bad fuel pump, clogged jets, bad fuel, water in fuel, etc. Try having someone squeeze the primer bulb when the engine is bogging. If it picks up, you probably have a fuel pump issue.

 

[j_martin]

Re: Mercury 50 dies, got me stumped

Depends on what's in them, and whether or not the little jets and orifices are plugged. The phase separated lower fraction of modern fuel is mostly alcohol and water. Won't fire for chit.

At any rate, if it's a fuel problem, don't fix it halfway. The one thing that burns down most 2 cycle outboards is lean running/fuel delivery problems.

hope it helps
John

 

[BoteBoy]

Re: Mercury 50 dies, got me stumped

As far as I know it is running on all 3 cylinders, it doesn't sound like it's misfiring but I will check and make sure.

The fuel tank is full of fresh gas and I cleaned the carbs pretty thoroughly making sure all holes and passages were free of blockage. There really isn't much to the carbs.

I did not soak the carbs in chem dip, maybe I should have. There are two brass tubes down the middle of each carb, one small one inside a larger 1/4" diameter one. Anyone know what the bigger tube is for? That is the one thing that wasnt real easy to get perfectly clean.

Where is the fuel pump on these? What's the best way to check it? If I crank the engine with the fuel line disconnected it pulses out a good amount of fuel, it seemed to be fine but I don't have anything to compare it to.

Should I do anything to the mixture screws or are they only for idle?

Thanks again for the help guys,

-Rob

 

[BoteBoy]

Re: Mercury 50 dies, got me stumped

Well I'm headed out this morning to take another look, I'll double check that all cylinders are running. Also bringing another fuel tank and lines to try then I plan to bring the carbs home again and soak them in chem dip.

-Rob