Have a 1996 Mercury 40, 4 Cylinder 2-stroke with oil injection. When I got the motor I cleaned the carbs, replaced plugs, checked Compression (120psi), changed water pump, and replaced the switch box and voltage regulator...which were bad. I also checked the stator, and trigger per manual and they were fine. I timed the motor at TDC idle and 30 BTDC at cranking speeds...which timed right at 32 degrees at WOT.
Heres the issue, at idle it purs like a kitten, and has TONS of power through the power range. When you hit WOT it backs off and surges like a limiter is kicking in or something. If you disconnect the throttle linkage and move the trigger separate (opening the carbs by hand) it'll pick up and max out timing and never skip a beat, just when you move the carbs to the max point is when it surges. The only way it don't surge while doing this is to advance the timing and keep the carb linkage about 1/2'' back from max point on the carbs. If this makes sense.
Can anyone offer some pointers on this....already spent a TON on electrical components on this motor. Thanks for the help.
Heres the issue, at idle it purs like a kitten, and has TONS of power through the power range. When you hit WOT it backs off and surges like a limiter is kicking in or something. If you disconnect the throttle linkage and move the trigger separate (opening the carbs by hand) it'll pick up and max out timing and never skip a beat, just when you move the carbs to the max point is when it surges. The only way it don't surge while doing this is to advance the timing and keep the carb linkage about 1/2'' back from max point on the carbs. If this makes sense.
Can anyone offer some pointers on this....already spent a TON on electrical components on this motor. Thanks for the help.
