2001 mercury outboard 25hp 4sroke electric start. will not ldle. l have replaced fuel pump and had carb serviced at dealer. l have replaced the fuel filter twice. l can start with fast ldle easily and drop idle to get into gear. once underway works fine. it will run well at lower speed but too low and it will stall. it may be a little harder on fuel. l have burnt about four tanks of fuel so far. l am running only premium now without ethanol. l took carb in to dealer twice and he found water. also new spark plugs.

SOURCE: 40hp 1987 yamaha outboard motor will run for 30-60

Sound like the fuel pump is not keeping up with the engine's demand. Check it out. Good luck. Hope this helps.

SOURCE: 9.8 hp mercury outboard shutting off in low idle speed.

My problem ended up being the spring on the reed valve being weak.But at the same time and while I had already had my carb broke down I took a can of carb cleaner to it and cleaned it. In order to replace the spring on reed valve you will have to buy a new one, but don't worry I only payed about $6.00 for mine. You may also look into replacing your primer bulb if you haven't already because may allowing air to build up in your gas line while you are basically idiling.Once you get the carb straightened out you may have to reajust it again. If I might be able to help you again you may contact me at [email protected].

SOURCE: My mercury 35 hp outboard motor idle's fine but won't run

While at the river try to adjust the fuel air mixture. When you are on the water it puts the engine under a load and if that dont work then dont be afraid to bump up the idle stop screw slightly.

SOURCE: 2003 115 mercury efi losing power

I am a Mercury certified technician. What you need to do is take it to a Mercury dealer and have them hook it up to the computer. It sounds like the engine could be in Guardian mode or possibly a high RPM misfire. It is not something that is common and the computer program that Mercury has for those is able to test misfires and all sorts of cool stuff. It can also tell you if the engine was broke in properly, how many actual running hours are on it and even at what RPM each hour was ran. It will be able to bring up all faults that it has had in the past and any faults that are current. I know that you are probably looking for a quick, easy fix but for this problem I dont think that there is any way around taking the engine in. For what it is worth, if they charge you for more than 2 hours to run it on the computer then take it somewhere else. I can fully test the engine with the computer in about an hour. The only reason that it would take any longer is if they had to put it in the water to duplicate the problem but most shops will have a test tank that is capable of running your engine under a load at full throttle. Sorry for the bad news but I cant think of any other way and throwing new parts at it is just going to get expensive quick.

SOURCE: 6hp Johnson outboard stalls & quits

go to an auto parts store and get a can of gasoline additive called seafoam. Read the label so you know how much to add to your 6 gallon tank. This stuff works wonders on outboard motors.