28Eliminator

I have fixed many boats with the exact problem you are having, and I can tell you that it can be a bad connection almost anywhere in the run circuit. Grounds are always on the top of the list as well as the kill switch. If it's a 96 that is the first thing I would change. I have found loose connections on the ignition switch, battery, main harness connector on the motor, and most recently a loose power wire on the alternator. I would also check the obvious; ie, Starter wires, big RED breaker wires on motor, grounds. If the ECU gets a drop in power for any small period of time it resets, basically killing the motor.

GMC271

I had a similar issue with the 502 in my 96 Formula; the motor would stumble at high rpm in rough water. Check the wiring harness that runs between the rear of the motor and the oil cooler. You may need to remove the mounting bolts for the VST and move the VST out of the way to see the problem. The main power wire, I believe that it is 10 gauge, has a non-insulated butt connector that is wrapped with cloth tape; the butt connector wears through the tape and it intermittently shorts out to the engine block. I wrapped mine with good quality electrical tape and covered the wiring harness with split wire loom to prevent the problem from occurring again. Hope this helps.

cloudmaster_321

Doesn't sound the same actually. Mine doesn't stumble at all. Just shuts off like turning the key off. I'm currently working on changing out the ignition switch, kill switch, checking main engine connector, and checking/cleaning main ground on the back of the block.

cloudmaster_321

Well guys, Ignition switch has been changed, kill switch changed. Rang out the kill switch wiring to the ecm, no problems. Also took a look at the key on as was suggested, it originates from the "ignition on" buss. I have found that my older fuse panel with the agc type fuses can be intermittent. Such as my cabin lighting not working, and i'll spin the fuse in the holder and the lights come back on. So I took some contact cleaner and a horsehair brush and cleaned the ignition buss and fuse. I've run the boat for 7 hours since, and hard, with no problems. I may end up changing out the fuse buss system to a new style blade type.

That's all for now.....