I just purchased a 1994 powerquest 257 with a 502 mag efi with a non existing outdrive. Me and a friend pulled the engine, replaced transom assembly, and then re installed engine. Anyways, the previous owner performed some minor modifications with the fuel system. He added an electric fuel pump and capped off the mechanical one. My question is as follows. Does anyone know where the hot (power) wire should be landed for an electric fuel pump? I understand that all it needs is 12 volts but would really not like to have a cheap toggle switch. I would much rather make it "turn key". I am guessing there should be an ignition switch on the engine harness somewhere but just not sure where it may be located. Thanks in advance!

Look the starter solenoid. there could be hot wire wich get voltage
when turn the key to standby power position. Mine 454's has so.

But there could be other correct / better place than that.

Be sure you take only control voltages in those wires to the fuel pump relay. Relay should take own power from batterie back of fuse.

So when you turn key, voltages control relay on wich
connect power to the fuel pump.

Thank ya. Didn't really think it would be that simple. Guess I will break out my voltmeter tonite and do some checking.

You can get all kinds of fancy depending on how you want to wire things up. The best way i have seen it when adding an electric pump to a motor that previously had mech is to wire it up through a oil psi sending unit that throws a ground signal when it has oil psi. This inturn will go to a relay that triggers the voltage on to the pump. You will also need a small momentary switch to use a priming switch for cold starts when theres no fuel in the system.
So to start a boat thats been sitting for a while you would hit the priming button for a few seconds to prime the system up and turn the key to sart the engine. Engine fires over and when the sending unit see's oil psi it sends the trigger to the pump relay and the relay triggers the pump....whala! And if anything goes wrong either with the engine shutting off or loss of oil psi it will cut the fuel pump off.

That is one great idea! I just may do that in the future but for now I just want to see this thing run.. Didn't get a chance to see it run before I bought it unfortunately... The guy already had it all apart ready for the engine pull. Well anyways thanks for the advice

when voltmeter is in dc value 20vdc+ area u cannot broke anything in anycase. Put meter black wire to the engine block and red one to the solenoid where you can see the wire coming. It should show 12+ v when you turn key to power on (not to the end where engine starting). After you find 12v in solenoid turn key of and check that voltage goes to zero. If work so then its perfect. I turn key same wait short while hear that pumps running and turn key to the end and engine start very fast and same to other engine and voila!