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I have a 2003 25hp 2 stroke mercery. Went out to run it yesterday and it started up fine and ran good for about 2 min then died. Messed around with it for about 30 min and the only way that I could keep it running was if the motor was tilted up in shallow drive. Does anyone have any idea whats going on here?
Water in the carb bowl, probably could find some in the tank as well. When you tilt it up it moves to the corner (for lack of a better term) of the bowl allowing good fuel to the main jet. Yes, idle as well as the pickup for the idle circuit is beyond and thru the main jet. I would start with a carb cleaning.
Thanks! How hard is it to clean the carb and how do I go about doing it?
Cleaning the carb is not hard , it needs to be removed to do it , the hard part is getting the choke,fast idle lever off, I take these off allot, and I still cuss them. All you will need is a carb/diaphram/inrichener plunger.
I just had almost this same problem with my 25 hp mercury 2000 model. I have never worked on a 25 motor before and like the above poster described the fast idle lever was the only problem. Just be sure of the way it comes off and it is not to bad. I pulled the carb cleaned it, blew air through the jets and reassembled and back on in a couple of hours. After a adjustment of the Needle behind the little push in plug on front of the plastic housing it actually runs better than it ever has since new. My carb and the filter had some stuff in it that feels and looks just like hard soap. Be real careful with the gaskets and you will be OK there!
Re: how hard to remove a carb on a merc. 25hp
The fast idel knob needs to be removed. There is a Phillips screw that pins the knob in at an angle. Back that almost all the way out. The knob will come out with the square cube. Pull off the horseshoe clip. Unhook the warm up link rod and fuel line. The carb will squeeze out of there, but it is tight. There is a bleeder hose at the bottom. Remove that. Remove the plastic linkage.
Inside the carb, remember which way the float went in. It will not run at WOT if it is upside down. The float height is 1".
If you need the full kit, it is ~$80 from Merc. The primer has a red rubber seat and a lock ring holding it. Find a blunt punch and stick in from behind and knock that out. Don't try to dig out the lock ring. That burrs the ring groove and it does not go back right. Find another punch to put it back in with. The seat only goes in one way. Make sure that the steel ball does not end up jammed into the coils of the spring. There is a throttle return spring in the kit. Don't touch that unless it breaks. There are several springs and pump diaphragms in the kit, just put back what was there.
Sometimes the fuel pump will leak out of the cover. A little perfect seal or high tack can be used on the edges of the gasket here.
When putting it back together, the cube is stuck to the side of the knob thread while the lever is pushed all the way down so that the primer pin catches the cube the right way. The L-end of the warm up rod must be pointing up toward the flywheel at the spark arm end. Set the idle needle at 1 1/4 turns to start. Adjust it richer until the bog disappears.