I have just got my hands on a 90 f150 xlt lariat 4x4 with the 5.0. I have an issue with starting it. It will only start by crossing the wires by the starter relay beside the battery. The previous owner only used it as a mudd truck so not a big deal for him but as i plan to use it as a DD then i would like to get the ignition wired correctly. If anyone can help with pictures or diagram of exactly how it is supposed to be wired from the key ignition plug all the way, i would really appreciate it. I definitely have my work cut out for me on this truck but cant complain on a free truck.

 

There is just a small wire feeding the top of the fender mounted solenoid. That is start signal from the ignition. They are known to corrode. The solenoid may have gone bad, too.