2010 Mercury 25 hp 4stroke loses power while running

[Fishin_Mike]

I have a 2010 Mercury 25hp 4 stroke that I have been having problems with. At full throttle it runs fine for about 2 miles then it loses power while the throttle is at full speed. After a minute of idling, it regains power for about a half of mile. If I prime the motor while it is idling, it regains power for a short period of time. I've replaced the fuel line and connector. Does anyone know what the problem is? Any help is greatly appreciated.

I replaced the fuel tank, new fuel line, connectors, and primer bulb. I've recently had it serviced at a local Mercury dealership. They told me the thermostat was stuck open and they fixed the problem. They were wrong. The problem still exist.

 

[fisics67]

Sounds exactly like the problem that I am having with my 2011 75hp 4 Stroke. Which I an 99% sure that I have narrowed down to the float in the vapor separation tank (fuel supply module). I finally pulled it apart today and I cannot get any continuity through the electric float switch.

Now I realize our motors are different, but the symptoms are very very similar. Might not be the float, but I think there is a good chance that your problem is in the VST.

 

[bobhol]

i had the same problem on my 2011 40 hp at 100 hours.The motor would intermittently not run without using the primer ball. I checked lines,changed bulb,filters(2),water separator etc. Drove me crazy!! i changed the fuel pump and it solved the problem last year. almost exactly 100 hours later the fuel pump went again . i changed it and it is fine again . took the first pump and discovered the piston was not free and was hanging up in the pump body ,so not giving a full pump of fuel. The second pump had a rip in the diaphragm.Between the two ,I rebuilt one good pump as a spare...the marina stocks the pumps which leads me to believe there is an issue with them ....hope this helps someone