75 mercury outboard stator or switch box

[db1971]

my motor runs fine until it hits water,It runs smooth, full throttle for about 15 min.then it dies.And it will not fire back up for about 45 min. on a hot day.Fires back up and it might run for 10 min,then dies.No fire nothing but it will still turn over.Could this be a stator or a switch box? What would single out one or the other?<br />Boat motor ser.#4752942 150 hp outboard<br />switch box # 332-2986a22<br />Or is there an easy test to find out which one it could be.<br />Thanks for the info

 

[dvchristoff]

Re: 75 mercury outboard stator or switch box

Some ideas, get a volt meter and a wiring diagram for your motor, then<br />1. When its cold(running)check stator output voltage and compare it to voltage when its hot(not running). Make sure there is voltage getting all the way to switch box through the rectifier. <br />2. The switch box is tougher to test. There are two wires hooked up to it and if either one of these supply voltage to the switch box they are designed to kill the engine. The mercury switch and the ignition switch. Something is getting hot and they might be shorting, maybe one of those two wires. Try disconnecting the two wires when it is not running and see if it fires. You can also then check voltage output from the switch box to the distributor when its running and not running and compare. Remember also when trouble shooting the electrical that the stator supplies power to the switch box, not the battery(starting) so you will not get power to the box and distributor unless the engine is turning(cranking or running).<br />3. So if everything checks out okay so far with voltage to the distributor then make sure you have spark at the plugs(when cranking) Coil is then good.<br />4. If you have spark at the plugs????????? Fuel is next. Maybe a vapor lock.<br />Hope this helps.<br />P.S. You might want to check spark at the plugs (when it will not run) first, because all that other stuff is there just to get that little spark to the plugs.