"I have a 1994 Merc 225 Black
"I have a 1994 Merc 225 Black Max 3.0L offshore. Purchased ast year on a 24' Wahoo. The engine has 386 hrs on it. It was in mint shape ran beautiful last year. Winterized it according to manual I purchased for that particular year (ebay). Set it up for this year ran fine on land. Took it out on the water, brought the engine up to 3000 RPM starts to surge and back down, builds back up then surges again repeatedly. Was told by fellow boaters it was the gas. Changed the gas out, still does the same thing. Rebuilt the fuel pump, changed all the lines even the primer bulb (yes the correct bulb)Changed water seperator then proceeded to rebuild the 3 carbs. Gave tune-up plugs, wires etc. Everything put back together correctly. Starts smooth runs nice at idle bring the RPM's up to 2800 to 3000 surges then backs down, surges backfires then backs down. (ghost throttle) any ideas before I finally accept defeat and throw in the towel. (Compression test read 90 to 95 all six cyl) Any Help????"
"I have a 1994 Merc 225 Black Max 3.0L offshore. Purchased ast year on a 24' Wahoo. The engine has 386 hrs on it. It was in mint shape ran beautiful last year. Winterized it according to manual I purchased for that particular year (ebay). Set it up for this year ran fine on land. Took it out on the water, brought the engine up to 3000 RPM starts to surge and back down, builds back up then surges again repeatedly. Was told by fellow boaters it was the gas. Changed the gas out, still does the same thing. Rebuilt the fuel pump, changed all the lines even the primer bulb (yes the correct bulb)Changed water seperator then proceeded to rebuild the 3 carbs. Gave tune-up plugs, wires etc. Everything put back together correctly. Starts smooth runs nice at idle bring the RPM's up to 2800 to 3000 surges then backs down, surges backfires then backs down. (ghost throttle) any ideas before I finally accept defeat and throw in the towel. (Compression test read 90 to 95 all six cyl) Any Help????"