Starter Problems

Hi everyone, thanks for any help in advance.

So my 66 F250 has had a starter problem since last October and I've had to basically stop work on it due to rains and I haven't been able to look at it until this past week. So at the moment, when I put the key in the ignition, lights come on, everything is fine and dandy, but turning the key, nothing turns over at all. All you'd hear is silence if you were sitting in the cab.

Battery hasn't drained, gave it a charging while I was fiddling with a couple other things and put it back in. Key is off and from the starter relay, I put the voltmeter on the lead to the battery and the other to the starter coil, 12 volts. From the battery lead on the relay to the line that connects with the starter neutral switch, 12 volts. But beyond that, I can't test at the starter neutral switch. Mostly because I have no clue where that is. I've traced that red blue line to the firewall, and it's a mess on the cab end of things.

So should I replace the relay or try to find the switch wherever it may be?

*note, it did turn over on Sunday, but wouldn't start. Then from somewhere a buzzing sound came and then I stopped trying, and it didn't work any more. On the engine end of things, the lead from the battery to the starter relay started smoking and the rubber cladding melted. I've since changed that lead to a 4ga.

So wise Ford forum gods, any advice you can bequeath?  
Beneath the hood, lies a beast.

first off....  DO YOU have a DIGITAL volt meter...  



print this chart....  run the first part of the test...    this will verify the battery has enough voltage to crank the engine.....




you can run test 1, 2, 3 and 4 while attempting to crank the engine...

but you are probably going to want to disconnect both sides of the battery....

count the wires on the battery cable side of the starter solenoid... remove the nut.. take the ring terminals off the stud and wire brush both sides of each ring terminal and the stud its self..

use a stainless steel wire toothbrush from the hardware or paint store...  usually under 5 bucks.. wooden handle versions have stiffer bristles..




perhaps i should explain the BUZZING NOISE....   when there is a dirty connection either on the positive or the negative side... when you go to crank the engine.. as you turn the key to the cranking position.. you may have enough voltage to engage the starter solenoid contacts.. but as soon as the contacts are made.. the additional current going down to the starter takes the voltage drop below the point where the solenoid coil winding can overcome the release spring in the solenoid..  so the solenoid releases.. as soon as it releases the voltage returns... and the solenoid pulls back in... only to have the voltage drop and it kick out.. yes.. thats the solenoid kicking in and out so fast it sounds like a buzzing..

clean and verify the battery terminals where the wires attach..

clean and verify the positive cable connection to the starter relay...

clean and verify the starter cable connection at the starter relay...

clean and verify the starter cable connection at the starter...

clean and verify the battery negative connection at the engine block..

there also has to be a battery negative connection to the BODY...  and another between the engine block and the firewall..  

Ford used the NSS in two places depending on trans type, either on column under dash or on the trans itself, it will be a switch with two wire plug, unplug it and run a jumper wire to each terminal on the plug, if it starts replace NSS...