I have a 1985 90hp. Mercury outboard. It fires but but won't run but a second or two after releasing starter key. I have good fire on a 6 cyl. Good compression all in the 120-125 range. I cleaned all three carbs. and run from a remote fuel tank with fresh fuel. Fuel pump is working well also. I know I haven't tried everything but I'm not sure what to try next. Thanks for any suggestions...I'm new to all this.