I have a 01 ranger that was recently sunk in the Chesapeake bay, recently the fuel pump will not turn on so I replaced a fuse, switched relays, and replaced the whole fuel pump assembly after plugging everything back in and turning the key the fuel pump still will not turn on. So I unplugged this big plug that is plugged into the cab and it was full of water and slime from it being submerged does anyone have any more tips for me to get my truck running or know what that plug is for?

 

It does A LOT, lol

In a 2001 Ranger its called C340, connector 340(in 2000 Ranger its C309)

There was a TSB issued for 2000 and 2001 Rangers, seen here: Technical Service Bulletin 2000-2001 Ranger electrical connector - Ford Ranger Forum

Issue was Water intrusion, but not from total immersion in a river or bay, lol, so in your case I guess it was

Dry it out as best you can and clean up any corrosion on pins and slots
You can use di-electric grease on the edges to seal it when you plug it back in
The point of using di-electric grease is that is does NOT conduct electricity like regular grease can so it won't cause shorts, but that also means you DO NOT want the di-electric grease to be on the metal pins and in slots that DO NEED to conduct electricity, lol

But I didn't think the fuel pump power runs thru that connector

Did you check the inertia switch in passenger foot well, its on the firewall behind glove box or behind the passenger side kick panel, looks like this: https://cimg1.ibsrv.net/gimg/www.for...42553f334a.jpg

This switch's red button will popup if there is an accident, but any sudden sharp movement can trip it, this cuts power to the fuel pump, it just a heavy metal ball that will break internal electrical connection if it's bounced one way or another, so mechanical switch
Towing can cause it to trip, especially if vehicle needed to be jerked a few times if its tires had sunk in the mud

The computer runs the fuel pump by grounding the fuel pump relay, but only for 2 seconds with key on, but it will ground it for those 2 seconds each time key is turned from off to on
Computer will not ground fuel pump relay full time until RPMs are above 400, cranking speed is 200rpms

I assume the CEL(check engine light) is coming on with key on, that means the computer has powered up
An no rapid flashing THEFT light, with key on, that will also prevent fuel pump relay from activating