Randomly shuts off, then restarts after it sits for an hour or 2?

[Schurkey]

I'm a bit confused ... so can either one independently power the fuel pump? Or does power need to go through both the relay and oil pressure switch, before operating the fuel pump?

If the fuel pump relay works properly, and the part of the oil pressure switch that runs the fuel pump fails, you'll never know the difference. Engine will start and run just fine.

If the fuel pump relay fails, but the oil pressure switch works, the engine will start and run just fine...but it'll have to crank long enough to build oil pressure before the fuel pump will run. The pump will not prime when the key is turned. But other than the extended cranking time, it'll run just fine.

Either one can power the fuel pump. GM built-in redundancy so that folks didn't get stranded if the relay failed. If both are working, they share the amperage load so they'd probably last longer before burning the contacts inside the oil switch and relay.

 

[Kens1990K2500]

If the fuel pump relay works properly, and the part of the oil pressure switch that runs the fuel pump fails, you'll never know the difference. Engine will start and run just fine.

If the fuel pump relay fails, but the oil pressure switch works, the engine will start and run just fine...but it'll have to crank long enough to build oil pressure before the fuel pump will run. The pump will not prime when the key is turned. But other than the extended cranking time, it'll run just fine.

Either one can power the fuel pump. GM built-in redundancy so that folks didn't get stranded if the relay failed. If both are working, they share the amperage load so they'd probably last longer before burning the contacts inside the oil switch and relay.

You've explained it well; thank you for the explanation/clarification.

 

[Dariusz Salomon]

I know many said that passlock shouldn't do it,but when I was reading about passlocks(yesterday-just googled) I found multiple mentions of exactly this happening because of passlock-engine shuts off.
I'm not saying that's the case here-I can't even verify the sources-maybe it was coincidence and those guys took it for a proof-just throwing in the idea-sometimes some trivial,seemingly unrelated ideas prove to be right ones.
Mine was doing this when tank wasn't full,but you said you just refuelled so it isn't it.

 

[letitsnow]

I know many said that passlock shouldn't do it,but when I was reading about passlocks(yesterday-just googled) I found multiple mentions of exactly this happening because of passlock-engine shuts off.
I'm not saying that's the case here-I can't even verify the sources-maybe it was coincidence and those guys took it for a proof-just throwing in the idea-sometimes some trivial,seemingly unrelated ideas prove to be right ones.
Mine was doing this when tank wasn't full,but you said you just refuelled so it isn't it.

Thanks. Blackbear removed anything like passlock years ago. The truck hasn't missed a beat since the day that I originally started this thread.

 

[letitsnow]

Just wanted to update this thread - I haven't had any problems since that day when the truck died. I have put on around 10,000 miles (pulling our camper) since then.

The only part that I replaced that tested bad was the battery. I am thinking that it was either the battery, or bad gas.

Thanks again to all who gave me advice when I was asking. I learned quite a bit.