Engine keeps running after power shut off

[dlogvine]

I had my 1998 Ebbtide with 5.0 Mercruiser sitting for almost 2 years. This year I installed new batteries, checked the fuel (it was stabilized and I also poured enzyme fuel booster), fuel was not gunked. Repaired starter. The engine at first was cranking but not starting. Used starting fluid, carb cleaner. Tried a soaked with gasoline rag on the carb intake. Same result, cuffed and started running until gas or fluid was done and kept dying. After about an hour of this back and forth, recharging the batteries and while they were recharging I used the other pair, so after that the engine revved up and started running. But now the problem is it refuses to shut off. First I turned off the ignition key but the engine kept on going. Turned off the power switch, so there was absolutely no power going to the engine. Still running smoothly as if nothing happened.
Shut it off with putting a rag over the carb intake and closing the air supply. Obviously, trip to the lake is postponed until the problem is resolved
Question is, what could have caused this engine to run without ignition power. I think there should be some hot spots on the pistons (maybe) that might cause this combustion and maybe another 15-20 minutes of running the engine with the marvel oil would clean them up?

 

[alldodge]

Need ore info about the motor
What is the serial number

 

[Bt Doctur]

and the alt has a shorted diode in it back feeding the system

 

[dlogvine]

and the alt has a shorted diode in it back feeding the system

the diode wont make any difference, the motor was running with the batteries completely disconnected.

 

[Bt Doctur]

the diode is in the alt. its backfeeding . try removing the orange wire at the alt output post

 

[dlogvine]

I had my 1998 Ebbtide with 5.0 Mercruiser sitting for almost 2 years. This year I installed new batteries, checked the fuel (it was stabilized and I also poured enzyme fuel booster), fuel was not gunked. Repaired starter. The engine at first was cranking but not starting. Used starting fluid, carb cleaner. Tried a soaked with gasoline rag on the carb intake. Same result, cuffed and started running until gas or fluid was done and kept dying. After about an hour of this back and forth, recharging the batteries and while they were recharging I used the other pair, so after that the engine revved up and started running. But now the problem is it refuses to shut off. First I turned off the ignition key but the engine kept on going. Turned off the power switch, so there was absolutely no power going to the engine. Still running smoothly as if nothing happened.
Shut it off with putting a rag over the carb intake and closing the air supply. Obviously, trip to the lake is postponed until the problem is resolved
Question is, what could have caused this engine to run without ignition power. I think there should be some hot spots on the pistons (maybe) that might cause this combustion and maybe another 15-20 minutes of running the engine with the marvel oil would clean them up?

the diode is in the alt. its backfeeding . try removing the orange wire at the alt output post

I figured out what was wrong. Actually 2 things. First one is malfunction in the ignition switch, turning off the key does not turn off the power from the battery. The dashboard is still working and engine is running. Second part is probably in the second battery connection. I hooked them up sequentially power terminal to the switch and negative of the first battery to the ground and negative of the second to the negative of the first. Somehow, it allowed the power to stay on even when the switch is turned off. Once I disconnected the second battery the switch worked and shut off the engine. Tomorrow with more light will go through the wires and see what was the issue with the power switch connections.
Thank you guys!

 

[ROY WILLIAMS]

I had my 1998 Ebbtide with 5.0 Mercruiser sitting for almost 2 years. This year I installed new batteries, checked the fuel (it was stabilized and I also poured enzyme fuel booster), fuel was not gunked. Repaired starter. The engine at first was cranking but not starting. Used starting fluid, carb cleaner. Tried a soaked with gasoline rag on the carb intake. Same result, cuffed and started running until gas or fluid was done and kept dying. After about an hour of this back and forth, recharging the batteries and while they were recharging I used the other pair, so after that the engine revved up and started running. But now the problem is it refuses to shut off. First I turned off the ignition key but the engine kept on going. Turned off the power switch, so there was absolutely no power going to the engine. Still running smoothly as if nothing happened.
Shut it off with putting a rag over the carb intake and closing the air supply. Obviously, trip to the lake is postponed until the problem is resolved
Question is, what could have caused this engine to run without ignition power. I think there should be some hot spots on the pistons (maybe) that might cause this combustion and maybe another 15-20 minutes of running the engine with the marvel oil would clean them up?

the gasoline 2 years ago the tank ......is a mess ............
my boat engine the gasoline, marvel mystery oil 10 gallons one OZ.
the marine gasoline additive 1 OZ. 10 gallons ....my boat tank is the fall dropping it of the gasoline ... then the truck gasoline tank !.
The pistons of the MMO the fall 1 OZ.

 

[dlogvine]

the gasoline 2 years ago the tank ......is a mess ............
my boat engine the gasoline, marvel mystery oil 10 gallons one OZ.
the marine gasoline additive 1 OZ. 10 gallons ....my boat tank is the fall dropping it of the gasoline ... then the truck gasoline tank !.
The pistons of the MMO the fall 1 OZ.

you would be surprised but with Stabilizer (SeaFoam) and enzymes, gas was still good and not it starts without any problems, turn of the key