I have got a 1994 Mercury 115 hp boat motor that is having issues with idling. I have noticed that it is trying to idle at 1800 rpms. I hear that it is suppose to be in the 600-800 range.

So...I idle down the motor with the idle screw just to see what would happen. It idles at about 1000 rpms for about 30 seconds and then surges back up to 1800 on its own and stays at the 1800 rpms. It never comes back to the 1000 rpms.

I have put the screw back to it location before I started just because I know there are other issues at play here. Can anyone help me out? I have not pulled the fuel pump off yet to check it out. I hear that there is a screen that may be messed up in there.

thanks in advance

Donny...Sounds like your problem could be in the exceleration pump circuit. The way it sounds is the engine is trying to idle on one of the bottom cylinders and if this is the case it could one of the nozzles that supply the shot of fuel at exceleration is leaking which will cause the high idle ....OPTI

Where do I find this circuit and is there a test for it? Also, do you know about how much that would cost?