Mercury bogs after running fine

[gdoss]

Yes, I'm new to this stuff, but you guys always seem to help. I have a 2000 Merc 60 HP. It cranks fine and then I idle for about five minutes to open water. Then go up to full throttle and it runs up to 5500 RPM and really is running great for about 200 yds. Then it just boggs down to about 3500 and will not pick up. You can stop or idle back and it still has no power or RPM's above 3500 once you try to plane out. Let it rest for an hour or so and the same thing happens.
You got any ideas?

Sad in GA

[Rebbasser]

Welcome to the forum!

No expert by any stretch, but my first thought would be to check the fuel lines/filters for clogs. There might be something that clogs the fuel line when under pressure but when the engine is stopped it unclogs.

You also might run a can of Seafoam through it if you haven't recently done so-it cleans all the crud out of the engine. Just be sure to change the plugs after doing so-the Seafoam cleans the engine but it will also foul the plugs.

[gdoss]

Checked all fuel lines and filters. Free flowing all the way to carburators. It does sound like it is starving, but it runs good for a short while.

[zooker]

check your gas tank vents sounds like it is not getting air to the tank..

zooker

[bassbooger]

My buddy had this same problem with a 25Hp Merc. We looked at everything on it and could never figure out what was causing it. We even changed the fuel pump, gave it a new fuel line and made sure that the gas tank vent was open all the way. Even tried running with the gas cap all the way off and still didn't help. He ended up trading the boat in for something newer, but we never got it figured out.

[Christopherkeene9]

May need a carb rebuild had the same thing happen with an older mercury. The fuel line had deteriorated and had clogged up the carb for cylinders 3 and 6.

[OUTLAW]

Check gas tank vent,Not an expert either, but thats what it sounds like.Then I would check the hose,any cracks ,youll be sucking air.Then carb.Good Luck.

[gdoss]

Thanks all of you. I'll try the vent deal first this weekend.

South Ga redneck

[thebus71h]

In racing we have this every once in a while, and usually more than anything it's the fuel mixture in the carb/injection.

Sounds to me like it's lean, and starving the engine of fuel, which could be the tank vent, or it could be something in the carburation or injection of the engine.

[gdoss]

Tried everything this weekend, and wondered if anything was going to work without some carb work. After a half a tank of gas, it cleared up and is running strong. Maybe it just needed running. The vent cap deal helped a lot to start with, cut occasionally it would drop back tp about 42 RPM. After a while it started doing fine and kept it up for about 20 minutes before I had to go.

Thanks for you help

So GA Redneck

[OUTLAW]

Thats good,Hopefully it clears up.Maybe you had to just blow some crap out of the carb.At least you didnt have spend any cash.Goodluck

[Rebbasser]

Glad to hear it is working. I'd still run a can of Seafoam through it-I do at least once a year. After doing so just be sure to change the plugs. while the Seafoam will clean the crud it will foul the plugs, but changing the plugs, well, is so easy a caveman can do it .

[bassintom]

Make sure it's pissin'.You could be having an overheating problem.It's also possible you have a bad t/stat(s),or the water intake is blocked.
If it's overheating this could cause problem as you describe.Is it oil injected?You may want to take a look at the oil injection system.
Where the heck is Laser when you need him

[gdoss]

It is now pissin fine. At first there was only a dribble, but checked it out and found a dirtdobber in line. Cleaned it out and that also helped some. Yes it is oil injected and seems to be using some oil as level goes down and smokes pretty good @ start up. I also found out why my switch key was not working. I took controls apart and found neutral switch was busted all to pieces. Straight wired it till I can get one. Got all the leaks JBWelded and a new plywood on front deck. Have spent most of last two weeks of spare (ha ha) time working on this boat and motor. Guess it was worth it if everyting works this weekend. Wil try the seafoam. I have a set of plugs I took out a couple of weeks ago. I think I'll put them in it to clean out with seafoam.

Thanks for all your help. Everyone!!!!!!!!!!!!!!!

So Ga Redneck

[1FASTLASER]

AH it still would be a VERY good thing to run a shock treament of Seafoam. What it now sounds like to me is the bowels had some trash in them and finally it worked through the system. A good dose of seafoam and then a pug change and prolly will run good for along time. Ole Reb gets the cookie on this one.