1997 Silverado fuel issue

Note the diagram for fuel pump. Make sure battery has a full charge and connections all good. The fuel pump prime comes through the relay. As you notice in the diagram, an oil pressure switch in parallel with fuel pump relay, if that switch and wiring circuit is working properly, once you crank it enough to bring up oil pressure and switch closes, the fuel pump will run regardless of the relay. You could unplug the relay and the vehicle would still start and run, might be an extended crank. If voltage for the pump is coming through oil pressure switch, there won't be any initial prime. Note the relay in diagram, there are two sides, the switch side, left side in the diagram. The control side, is right side of relay in diagram, that side needs voltage and ground, top wire is voltage, comes from pcm, bottom wire is ground on that side. I could keep talking, but, I think I'll stop, for now. good luck

Just wanted to add, spider fuel system, key on engine off, 60--66 psi. Start up fuel pressure can be critical after it starts it will run with less pressure. The spider fuel system is noted for problems. Just my opinion.

So would the stall and stumble be related to the relay in any way? It seems the fuel pump is being powered through the OPS instead of the relay

I don't think the stall and stumble would be related to relay, possibly the fuel pump? Yes, it sounds like the fuel pump is being powered through the oil pressure switch, in diagram. With the spider fuel system, key on engine off, that fuel pressure you listed isn't correct. You could pull relay, use jumper wire at cavities on switch side of relay, terminals 30 and 87, one of those terminals fuse protected and hot all the time, the fuel pump should run, don't even need to use key. If the pump runs with jumper, has to suspect control side of relay has a problem, either voltage or ground.

You are very knowledgeable. If the truck starts without being primed is there a chance that the fuel pressure could be just low enough to starve the engine for fuel causing the stall or stumble, or would a properly operating fuel pump "catch up" and supply the correct fuel pressure? Just trying to eliminate everything before buying another pump.

Like I said that spider fuel system is noted for problems. After the vehicle is running, it will run with less pressure, so that pressure you listed, engine running, will probably work, for running, but poor start up. There are people that answer questions here that are better than me.

So should we rest the relay socket to determine why the pump is not receiving the signal to prime? This is odd too. My son told me last night he has been using non-ethanol gas for three days and it has not stalled or stumbled once.

Maybe ethanol was causing problems? As far as the control side of that relay, you could use both ends of test light on those terminals, have helper turn key on, it should lite for a couple of seconds.

Ok. Problem solved we think. We tested the fuel pressure again. Initially, we got 0 prime pressure but after turning the key a few times to on, we got 60 psi. But the pressure didn't hold. It immediately went back to 0 psi. But the truck cranks and runs. 52 psi idling then up to 60 psi increasing rpms. We replaced the cam sensor and distributor rotor. The old rotor had a piece of plastic chipped out of it near the center contact. Its been 4 days and the truck hasn't stumbled or stalled yet. We are thinking the prime isn't holding because of a faulty pump check valve.