MERCURY 1998 200 EFI cuts off intermintely

My 1998 200 EFI has just shut down while running four times in the last six months sending water over the transom ...the whole nine yards...Exactly like the kill switch has been activated... All but one time it has been while running on step the last time a few days ago it was at idle. After this happens it will start again after it has been shut down for a period of time. I was thinking I had voltage regulator problems because the volt meter on my depth finder showed 16-17volts at times while running and the tach was not functioning properly. I replaced both regulators and the over voltage problem went away and the tach works as it should now. Two days ago the engine shut off while at idle and after fishing down the bank for an hour or so it started normally. I'm thinking new start switch and kill switch...each time this has happened it started normally after a length of time (in the storage shed). This engine has been recently overhauled and is on a Nitro Bass boat. The ignition switch is on the switch panel not on the throttle...Any ideas??

Most likely stator is failing but with the overvoltage problem the high pressure fuel pump could be going south. Next time it quits listen if the fuel pump comes on just by turning key on. if not its pump or possibly bad driver board in ECU. If you hear it then check to see if you have spark.

faztbullet said:

Most likely stator is failing but with the overvoltage problem the high pressure fuel pump could be going south. Next time it quits listen if the fuel pump comes on just by turning key on. if not its pump or possibly bad driver board in ECU. If you hear it then check to see if you have spark.

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First of all Thanks for the reply fazbullet....I've been looking for a wiring diagram for this motor (without success) but I've seen that there is a "mercury switch" (which is to prevent the motor from starting when it is trimmed up past a certain point). This switch is connected to the kill switch circuit and the ignition switch boxes. I haven't been able to find out for certain if this switch is on my motor or not but it could be the problem. I'm going to disconnect the kill switch wires at the ignition switch boxes and install a new start switch and wires leaving the old wiring disconnected and out of the circuit.This will allow me to turn the motor off but disable the kill switch. It seems to me that the kill switch circuit (or the 12vdc into the ignition switch boxes) is interrupted by a broken or shorted to ground wire somewhere. When it cuts off it's instantaneous stop no sputter or anything.It does start again after some passage of time that's the puzzeler.... Any thoughts on this?

There is no mercury switch and there is no 12V into boxes..like I said either stator or fuel pump circuit