Cranks but no start issue

I have a 2000 S10 LS 2.2 FFV with a manual transmission. I recently replaced the fuel pump and it ran fine until a month later it stopped working again. I contacted the manufacturer and they replaced it with another brand new pump but this time the pump won't prime. The fuel relay clicks when you turn the key to the ON position. The ECM-b fuse is intact. I tested the wires at the fuel pump with a test light but it there is no power going to the new pump. There is a fuel pump primer slot in the fuse box that when energized, the fuel pump starts to work and the truck would start right up. I also noticed my dash warning lights (seatbelt, Airbag, ABS, Security, etc.) including the odometer window light won't come on all except for the "service engine soon" light. Also, the radio and heater won't turn on. I also replaced the oil pressure switch and ignition switch but still no luck. I checked all body grounds and they are very well secured. I am a backyard mechanic with no experience in electrical systems. I would appreciate anyone's advice on here. Thanks!

Let's start at the RELAY.

Pull the Relay. With an incandescent test light connected to Battery (+), touch terminal 86 . It should shine, brightly. Now, connect the test light to Battery (-) and touch terminal 30. It should shine, brightly. Touching terminal 85, the light should shine, brightly, when the key is first turned on, and while cranking.

Touching terminal 87, the light should shine. The ground is coming from G416 THROUGH the fuel pump. If you replace the test light with a power-probe, or a fused jumper lead, connected to Battery (+) (or terminal 30) and touch terminal 87, the fuel pump should run.

Thanks for replying. Relay clicks when you turn the key to the on position but you will no hear the pump prime. Also, the only light you will see in the dash as soon as you turn the key to the on position is the "Service Engine Soon" only and nothing else. No odometer, seat belt warning light, ABS light, or security light, etc. won't come on. On another forum, they said that the ignition switch might be bad so I replaced that too but unfortunately didn't rectify the problem. Going back to the fuel pump, there is a primer port next to the ECM-B fuse (circled in red) that when energized, you hear the fuel pump prime and the truck will start right up. Is it possible that the wires leading to the fuel pump bad?

I added the diagram that shows the feed wire forthe prime.....

The prime wire is simply tied into the relay's feed wire to the pump. Physically this takes place within the fuse/ relay box. You state that you can hear the relay clicking.....so most probably the load side of the relay is bad. You may just pull another relay for testing purposes out of its place and put it in the fuel pump relay's place.

Or you put a fused direct voltage feed to pin 87 in the relay socket.

I switched a couple of known good relays around already but no luck. Let me try feeding a direct voltage to 87.

You can check the integrity of wiring in the fuse box by continuity from the prime connector to the terminal 87 in th relay socket or, while powering up the prime conector, look for voltage at the same terminal 87 at the relay socket.

juergen.scholl wrote: You can check the integrity of wiring in the fuse box by continuity from the prime connector to the terminal 87 in the relay socket.

How do I do that? Can I run a wire straight from the prime connector to terminal 87?