2000 jimmy fuel relay switch

What fuel pump switch are you talking about ? Has fuel pump relay (switch) controlled by the VCM - vehicle control module . Testing the fuel pump relay circuit's is the way to diagnose.
https://www.youtube.com/watch?v=McnXLcJNVfI&t=2s

Most likely a Relay is out. Remove one from another say the horn's relay or the A/C's relay and switch it with your lights relay and if the lights are working, go buy a new relay to replace the A/C or horn relay.

This might apply .. but it for a 1999 Jimmy:
Electronic Fuel Pump Computer Problem6 Cyl Four Wheel Drive

Your symptoms could also be do to other issues ... not just the fuel pump relay. Read the embedded link within the 2carpros response.

Good luck with your troubleshooting

The pump is powered by the relay. The relay is grounded by the computer. It gets a ground signal for the first 3 seconds, then only if the computer sees oil pressure or RPM to know the engine is running.
You should be able to ground the relay and run the pump for several minutes. After 30 seconds you should be at max pressure.
Normal pressure is 15psi for a truck that has throttle body injectors such as a mid 80s model, and 65psi for trucks that have port fuel injection like yours.
You may have the wrong pump.

replace electric part of ignition (everything goes threw it)

There is no reset switch for the fuel pump in this vehicle according to the stuff I am finding. There is a relay located in the power distribution box under the hood. You will need to test that, if it is working then the problem, assuming it is the fuel pump not powering up, is most likely the fuel pump itself. From what I am seeing these vehicles have a history of fuel pump problems from the Anti Rollover cutoff and accident safety switch built into the pump itself.

Fuel pump relay or fuel pump,or ignition switch

Fuel pump, fuel relay, fuel regualator, fuel injectors, camshaft positioning sensor, fuel filter, etc. Need special tools to diagnose properly, do you have them? Doubtfull, I don't have all of them and I've spent thousands on my tools. I can do a guessing game with you but I prefeer not to lead you astray.

There is a short in the signal switch mechanism in the steering column. What you hear is the signal relay. When you brake does the sound stop? If it does then this is the reason. Excess wear and conducting grease has created this short. The switch can be acessed by splitting the steering column and using very small tools and fingers!! you can remove it. Detailed instructions can be found on the net. This is a common problem with jimmys, astro vans and pontiacs.

Have you hooked up a fuel pressure gauge to the test port on the rear of the intake, drivers side. You can get a fuel pressure tester for about 40 dollars at a part store. It is a real good tool to have in your toolbox. If your Jimmy can't build 55 psi, it won't start.