My '90 F150 won't start. Help?
 

So, I have a 1990 F150 XLT Lariat 4x4 and it's been having starting issues. The battery and starter both test good. At first, it was having a weird problem with the engine temp gauge going really hot upon start up and slowly falling back down, so I replaced the engine temp switch. Realized the headlight switch was bad at the same time, so I went ahead and replaced it. I'm replacing the positive and negative battery cables today, because they're both corroded through. Going to put some Autolite Copper Core plugs into the engine today as well. Also, going to look at the Ignition Control Module and Pick-up Assembly on the distributor- already have replacement parts for those, if I find replacement is necessary. The engine is fuel injected. I hear the fuel pump prime when I turn the key and I do smell gas. Has anyone else had this issue with their truck? If so, what fixed it?

You don't really say what the issue is.
Does the motor not turn ?(what motor is it?)
Does it turn but not fire ?
Does it make noises ?
If it's turning but won't fire, you have to check for spark.
If you have spark, you have to check for correct fuel pressure. A pump priming noise is a good sign but it doesn't mean all is well with the fuel system.
If you have spark and correct fuel pressure, you have to determine if the injectors are opening. A faulty TPS can shut down the injectors. So can the ecm.
You can bypass the fuel system with a 3 second burst of starting fluid into the intake then turn the key. If it starts then,(for a second or so) but not without starting fluid, you have a fuel issue.
If you have fuel and spark the next likely issue would be timing.
It takes a little time and maybe a little money (to buy a fuel pressure gauge and multimeter $75 ?) but it's far cheaper in the long run to do the tests and determine what the problem is and replace that part (instead of throwing parts at it and crossing your fingers).

Chris 1,
The issue is that the truck cranks, but will not start. It has a 351 Windsor engine. Fuel Pressure is on my list of things to check. Was also thinking it might be an EEC issue. Does that sound viable to you?

Crank but no fire could be lots of things. So - test for spark. That's crucial. If you don't have a spark it's not going to fire. If you do you can move on.
Test for fuel pressure (gauge). Truck won't run without pressure at the injectors
Test TPS (feb 22nd should have a post). Injectors won't open if the TPS is no good.
If those (most common) things don't show you anything amiss, you can start digging a little deeper.
Have you checked for codes. Just call me Sean has a really good writeup at the top of the page. Truck has a computer that will try to tell you what's wrong.