S-10 fuel pressure codes

I recently put a 4link suspension in my 98 S10 and had to remove the fuel tank for additional room. I installed a fuel cell in it's place. Now the check engine light stays on. I had the codes checked and it says low/high fuel pressure. All the lines are hooked up just like the stock tank. Is the pressure sensor in the tank or elsewhere. The truck runs perfect but I can't get the truck inspected with the light on. Help!