chevy 2500

Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

You need to check fuel pump pressure to the fuel rail. On the rail is a schrader valve. That is where the pressure gauge connects to. If you look on our homepage under the DIY section, there is a video and directions for checking fuel pressure. Do that first. You will need a fuel pressure gauge to check it. Most parts stores will lend you the gauge.

If there is no pressure, chances are the fuel pump has gone bad. It is located in the fuel tank, and the tank needs removed to replace it. However, before just replacing it, make sure there is power to it to eliminate other potential issues such as a faulty fuel pump relay, ground, broken wire, or a bad connection.

what is voltage suposed to be going to fuel pump, is this on when the key is on?

You don't have to worry about that until you check the fuel pressure. The pump powers for 2 seconds when the key is turned on and then again after it sees a tach signal.