On most vehicles, it is normal for the fuel pump to turn on for a couple seconds and then shut off until the engine starts. The fuel pressure will build up and stay pressurized. I think it is a safety mechanism. You wouldn't want the fuel to continue to pump in an emergency situation like a fire or crash when the engine is no longer running. I would have the fuel pressure checked. Most shops have the capability or you can buy a fuel pressure tester. A fuel pump can come on and you could still not have enough pressure for various causes. The fuel pickup is broken, the pump is weak. the filter is clogged, the fuel regulator is malfunctioning. If you had the fuel pressure tested, you can rule out all the issues with fuel supply. then you can look somewhere else. you should be getting a signal from the computer that drives the relay. You may also have a fuel shutoff relay that could be causing the issue, but before you start chasing trons, make sure you have the correct fuel pressure.
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Something is closing the line or redirecting the fuel. I bypassed the relay, can hear a hissing at the rear of the engine. Pump seems to have very good pressure.
Code reader shows no codes found, which is weird.
I can not blindly replace components. I know thats what they would do at a shop, start replacing stuff till they hit the problem, then say it needed all that.
Doesn't make since that I spray fuel in n it cranks but bypass the relay where the pump has to run and it doesn't even try to crank. Seems if the pressure was low it would at least try, but it sounds like it gets absolutely no fuel, unless I spray it in.
I wonder if the pressure regulator can close the fuel off or redirect back to the tank? If so, how could I test without complex equipment?
Sorry if I sound aggravated, I use the truck for a living, I'm so screwed.