Re: Mercury 500 electrical problem?
When you shut it down does the problem seem to go away { shut down the throttle back to idle in gear }
If so you may want to check the fuel pump. I had a 650 a while back that had the same problem you discribed, rebuilt the fuel pump and prob solved.
check the carbs also, some junk in there could lead to a simular prob.
check the vent on the fuel tank. I know that seems silly but I have done it myself on occasion.
Check for leaking tank/engine fittings. The O-rings on the fittings can get cracked and leak air, this will also cause the discribed problem.
Somethings to remember with these old Mercs, if it will idle and rev up most likely not electrical.
There are about 40 more checks you can make to ensure good engine performance. If you don't find any problems with the fuel system then run the motor again till it starts to fall down and chech the compresson. Start with # 4 and work your way up. U could have one cyl. partially holdered and it causes problems after warm up. Seen that too.
Good luck
