When your key is on, engine is off, is it suppose to sound like the fuel pump turns on when you turn on your headlights?

 

What do you mean? Your headlights whirr? Or they click?

 

the sound when you turn your key on, the one that is a humming sound that only goes for a couple of seconds then quits....except....if i have my headlight switch all the way on, the sound never stops.

 

Is it coming through the speakers?? Could just be some electrical pull.

 

That's weird. If you think the fuel pump is running with the headlight switch on then listen at the gas cap to see if it really is. Some wires may have fused together connecting them.

 

nope, not coming through the speakers.


The big issue is, i can turn my parking lights on and everything is fine, but when i turn on my headlights (if the engine is running), it acts like a kill switch and kills the engine. all the rest of the electrical still works.

While troubleshooting a couple of things, i noticed the noise when the headlights are turned on and the key is in the ac position. Seemed kind of odd to me. After letting it sit for a few seconds, listening to it, I attempted to start the truck, and it would turn over but wouldnt fire. after a couple of attempts it fired up. and that was the only time that its done that was after listening to that noise. Does this make sense? if not ill try to explain it better.

 

could that cause it to kill the engine by flooding it out?

 

It wouldn't flood out, the regulator returns the excess fuel to the tank. Electrical problems are tough, a power wire may be grounding out with the switch on or something like that.

 

oh ok. Its definitely the fuel pump that is running with the headlight switch on. i put my ear to the front and back gas caps, it was the front. so i flipped the tank selector switch, and it was coming from the back gas cap. Would it be safe to assume that it would be somewhere between the headlight switch wiring and the tank selector switch wiring?

 

You didn't post the year, but judging from your picture ('92-'96) I'd say the short is near the fuse/relay box under the hood.