98 Silverado starts but will not stay running

My 98 Silverado, 350, wont start. I am sure the fuel pump went out a couple of months ago, so have replaced the pump and filter. Also the relay. The truck will start but then die almost immediately. Acts as if it is starved for fuel. Should I replace the fuel pressure regulator, and if so where is it? Or admit I'm beat and take to a mechanic?

Have you pressured up the fuel system with a guage attached at the test port? The fuel pump has a secondary ("fail safe"), ciruit through the oil pressure sensor. In case the relay fails the secondary circuit runs pump as long as engine is running. I dont know if this helps you are not, but I thought it might be good to know that.

This sounds like the "security" circuit. I'm pretty the vehicle uses Passlock 2 VATS, with a resistor wire going to VATS processor. If something in there is bad, it will put vehicle into "tamper" mode, which means you have to wait and try again. It will reset, but if the wire or processor is shot, then it may be entering tamper mode every time.

I've been having this problem myself. I'm not a real expert at this. Ask a GM tech, if you know one, or try someone who is experisneced in car alarms and remote starters.

Dunno if you found the answer to this, but my truck had same type of problem and is now perfect. I think your issue could be with the security wire. Here's the thread that I started: http://www.automotiveforums.com/vbulletin/showthread.php?p=2656698#post2656698

Just a thought. I took my truck in for a simular problem. After diagnosis, they told me it was the ECM. They replaced it along with the cap and rotor. It still had the same problem once I drove it home, until I replaced the fuel pump. I had replaced the fuel pump once already this Spring. This time I used a Delphi brand pump. Hope this helps.