I have a 1997 Johnson Venom 200 hp outboard, at 4000 rpms it begins to "surge" going up to 4600 to 4800 and falling right back down. It starts up fine, and runs great up to that point. I have changed the plugs, checked the wires, all seem to be fine. I have changed the fuel line from the tank to the new fuel filter. I have also changed the priming bulb. Any ideas?

I assume it has carbs. Whenever my Merc surges it needs needles and seats. On the Merc you can test by hitting the enricher. If the motor speeds up you are not getting enough fuel.

90% of the time you have a surge it is because of a lack of fuel. You might want to check the fuel filter, most are hard to get at under wiring on the port side. Check to see if a fuel hose is collapsing in a bend. Check all fuel hose connections from tank to VOR pump. VRO pump may be getting week. Lot of guys are changing the VRO motors over to an electric inline low pressure system and mixing oil.

I know this sounds dumb but, when my does it the fuel is just to low for the pickup in the tank snd its sucking air.

A surge can also be from a loose connection in the ignition system which can cause a spark plug to only occasionally receive spark.

No that's called a skip. Surge is different in the fact that it is a slower up and down of rpm`s and ignition miss or skip will be immediate up and down of rpm`s plus you normally can hear a cylinder dropping out.

Just try a new set of plugs. My boat was doing the same thing an a new set of plugs did the trick.

and heres your sign

Thank you for the clarification in terminology.

Still, check connections.

I had the same problem with my 140 Mercruiser. I rebuilt my carb and replaced the float with no success. I thought it was the check ball in the accelator pump chamber because when I first took apart the carb, there wasn't a check ball in it. But, that wasn't it either. Checked the spark plugs and it all checked out good. The fule filter on the carb fuel intake was very dirty. When I replaced it, I thought it would solve the problem, but that wasn't it. I thought it was the fuel pump--so, I removed the cover on the fuel pump and realized there was another fuel filter in there. The filter was nasty and coverd what looked like brown mud. Instead replacing the filter, I decided to just put the cove back on without the filter and put in a clear see-thru in line filter just before the fule pump. Took her out to the lake and she ran like a champ with no surges or bog downs. After about 10 minutes of testing her out, I took her back in. As I approached the trailer, I started hearing some knocking from the engine. Once I got her out of the water, I removed the drain plug and a bunch of water came running out-this was way more than usual.Took her back to the house, put muffs on and ran the water. Fired her up and noticed the engine was running hot. Looked to see if water was coming out of the water exit hole and no water was coming out. Looked around the engine and found lots of water coming from under the engine. Removed water hose from thermostat and water was flowing. Seems like I blew a gasket or have a crack in the exhaust maifold or worse, engine block.

Anyone know what it could be, which all of a sudden caused no water exiting from the outdrive?

Fixed one problem, which seems to have caused an even bigger problem....good grief...