1992 K1500 wont run?

Ok so the weird thing is that it is getting power to the starter and thats whats turning the motor over. So I must be getting spark cause the gas helps it to start (or starting fluid) the other weird thing is that the only lights that come on is the battery light and the check engine light on the dash. The instruments are not working when I turn the key forward and my head lights or any other lights wont come on even if the truck is running with me putting gas to it all the while. All the plugs seem to be connected properly as to what I can see. I dont think its a loose ground because my starter is getting perfect connection and I have a perfect battery. I have searched all over the internet forums for similar problems but cant exactly find the same thing. Then I found this website. Thanks for advance for any helpful replies. P.S. Was wondering the truck I have and the motor I got out of the can are both the same year. Thinking maybe I would have needed the wiring harness from the old van or something idk if it would be different or not I heard the astro is pretty much set up on a fullsize truck frame. Thanks

-jb

I had a guy that I know come check the relay and he said it was getting power but I have not checked the fuel pressure I will do that probably tomorrow and get you to you but it still doesnt make sense that im not getting power to anything in the cab itself. The guy the came over said that he coudn't even hear the fuel pump come on. Thanks in advance if I find the fix I will reply soon with an update

Hey thanks for your replies! I have a strong hunch that its the ignition switch cause I seen that people are having the same exact problems with there truck and that was the culprit. I was just wondering if t is possible that thats why its not getting power to the fuel pump cause I noticed that my ignition switch was not working properly the other day I turned my truck to the on position and then turned it off and pulled the key out and my check engine ligth and battery light was still on kinda flashing off beat. And ps where would the ignition switch fuse be located its a base model truck with no power doors or locks or anything like that.
Thanks in advance for your replies