I have a 99 chevy truck and their is no signal going to the fuel pump. Ive checked the relay and if I jumper the relay I can make the pump work. is their an oil pressure fuel cut off? If I crank the engine their is no oil pressure. What could it be that would cause the cpu not to turn the pump on?

The oil pressure switch is also the fuel pump cut off switch.

So why is it when I turn the key on I dont have a power to the fuel pump?

The oil pressure switch is also the fuel pump cut off switch.

The oil pressure switch is only a saftey switch to keep the fuel pump running if the fuel pump relay circuit quits.
It is only along for the ride if fuel pump relay and circuit is working good.
Will the truck start and run if you jumper fuel pump?
MT