When you turn on your ignition, (without starting the engine)well that was a stupid thing for me to say wasn't it? ANYWAY- with the key on you should hear the fuel pump humming under the truck. The left tank pump is very noticeable and when you switch to the right tank it is a bit quieter but still a noticeable hum. Under the steering column there is an electrical connector for your ALDL . By jumpering out the 2 pins on the farthest right with a paper clip, you can cause the computer to display codes on your instrument panel speedometer. (Key on) The "check engine" light will flash. It will flash a series of codes for you. You have to count the flashes to interpret the codes that the computer is sending. It might flash six times and the two more- and then six more flashes, then two more again. It is flashing a code 62. Every code is flashed 3 times. Then the computer begins it's flashing sequence again. Try it and tell us what codes the truck is sending.