problem on my mercury outboard, please help

[alffy]

I have a 1999 25hp 2 stroke mercury outboard and when i get it in the water i put it in gear and give it gas and when i do that it starts to bog down and go dead, but it will idle all day long. what could be the problem with this and what could i do to fix it. thanks.

 

[iskibumi]

Re: problem on my mercury outboard, please help

I have the same problem with a 45hp merc. I have searched the web and have yet to find an answer. Have you had any luck? Does your's run good even when revving up in neutral?

 

[rg2]

Re: problem on my mercury outboard, please help

Check the compression in both cylinders and post the results. You can rent a compression tester from most auto parts stores and it's a very simple test to perform. If you don't have good compression then it could be that the engine is not "sucking" enough gas in when you accelerate.

 

[robertheckmo]

Re: problem on my mercury outboard, please help

I had similar poblem with older 50 hp Thunderbolt. If you can rev engine in neutral, you might look for trouble in lower unit. I wound up overhauling lower unit. It would idle and putt along at idle fine, when I tried to accelerate, it would bog down. the main bearing in the lower unit was toast. Just a heads up. Bearing at Mercury dealer $35, at local Bearing Heqadquarters $9. Seals also available there. Bob

 

[will941s]

Re: problem on my mercury outboard, please help

Take the carb off and clean/rebuild it. Check and change the lines also. Make sure the vent on the gas tank is open. More than likely the jet in the carb is not letting enough gas through under a load. Also may not be a bad idea to do a compression test. If you've never cleaned and rebuilt your carb, then your past due. Once you try that, you may want to follow the procedures for a link and sync also if that doesnt help. When you rebuild the carb....don't touch the idle needle. Just take the carb apart, clean it with carb cleaner and compressed air, replace the gaskets and seals and put it back together. Try it, if it don't run like it should, then start adjusting.

 

[rosser1]

Re: problem on my mercury outboard, please help

clean carbs is a good start, new fuel, STA-BIL !!!

 

[Bob_VT]

Re: problem on my mercury outboard, please help

A two cylinder 2 stroke will run and rev up on one cylinder..... you should verify the spark and compression in both cylinders along with the other items mentioned above.

 

[alffy]

Re: problem on my mercury outboard, please help

Thanks guys for all the help. I'll try these things then post my results

 

[MurkySkeeter]

Re: problem on my mercury outboard, please help

mine never acts like its going to die it just SUCKS gas and never really hits the power at all. but idles fine also. Ive got a compression tester ill check that. Is there a link available that has a step by step on the carb removal and rebuild?

 

[MurkySkeeter]

Re: problem on my mercury outboard, please help

SO.... both cylinders were pretty much exactly the same on the comp test. First full pull went to right over 40psi_ then to over 90 then held right at 120psi . . . . . .

 

[Surfer Dave]

Re: problem on my mercury outboard, please help

put some SeaFoam in the gas and run the engine in the water, the SeaFoam will clean out all the crap that has built up in the lines and engine.

 

[MurkySkeeter]

Re: problem on my mercury outboard, please help

New Champion plugs and cleaned out my fuel filter and mine ran like a brand new engine today out at Smithville Lake! Big SMiles on this end!!!!!!