outboard surging - The Hull Truth

tterrien · 08-24-2009, 06:50 AM

02 Mercury outboard surging and dropping RPM'S after running 20 minutes or so. Pulll back to nuetral for a minute and throttle back up and sometimes its fine other times it does it again and I put it back to nuetral again and try again. Could it be an stator overheating? Doesn't happen everytime out which makes it more aggrevating. Could it be a battery issue? I might be crazy but I think it only happens when I run it on 1 battery. I did some test over the weekend and it did it on one battery but not when switch was on both. I even ran it on seperate portable tank to see if it was fuel related and it ran the same as on the boat tank. Thanks for any help you can give me.

A1 Outboard · 08-25-2009, 06:05 AM

Mercury are noted for stator problems. but it could also be a fuel problem. The fuel system can be easily checked for pressure and vacuum. You didnt mention what engine you have, so it is hard to know what ignition system you have. Carbureted engines do not use battery power for ignition. Keep an eye on the volt meter when the problem occurs as it may give a clue. More info about the engine would be helpful.

tterrien · 08-25-2009, 08:28 AM

The motor is a 02 Mercury 2stroke carb saltwater (not opti or efi). Could the stator act up intermitantly or would it just go bad? Some days I have no issues other times it will do the surge, drop from 4000 rpms to 3200 and then start surging like its starving for gas but I bumb the throttle up to 4k again and it goes and may drop again and I repeat the throttle up and sometime it clears. If not I put it in neutral for a couple of minutes then throttle up and most times its fine. Going out of my mind trying to figure it out.
Thanks for your help.

A1 Outboard · 08-26-2009, 07:35 AM

Stators generally dont act up intermittently, but it is possible. Heat under the flywheel can cause breakdown of the insulation in the stator. I still think a through check of the fuel system will turn up your problem.

tterrien · 08-27-2009, 10:10 AM

Thanks. I will check out the fuel system and hopefully find something.

Tommyboy · 08-31-2009, 03:35 AM

I had this same problem before. It drove me nuts!! It ended up being a fuel issue. I replaced all my lines from the tank up and it still didn't work. It ended up being a partly clogged screen in the hose inside my tank. I just removed the screen and let boogy type of crap go to my 10 micron filter and she was fine from there on.