2000 Serria won't start

I have a 2000 GMC Serria 4X4 ext cab. Occasionally it will not start it turns over but the fuel is automatically cut off. I beleive due to a security system issue. I wait for exactly the same amount of time each time and then it starts. About 12 to 15min never really timed it. Moisture and cooler damp situations seem to play a role. Any help is appreciated.

I'm having the same problem I think. See my post dated 11-6-2004.
I too believe it's dampness related. It has not acted up for about 10 days now which is about the last time it rained. I sure am looking forward to a solution.

I have the same problem, I haven't noticed it when it rains though. Two different shops told me that my car starter is messing with my security system and it shuts the fuel off. they claim that because you have to splice into the ignition harness for aftermarket starters, this problem occurs often. I haven't ripped mine out yet.

I HAD the same problem. I have a 99, old body style 5.7. Same problem, damp, rainy weather was when it would happen. Mine would start for about 1 second then die. Might start the next try, maybe 15 minutes to hours later. Brought it in to the dealer and had them change out the switch assembly (at my request) since there are contacts which have to kick in to keep the fuel pump running (I think). As much as I hate just changing parts, this wasn't it. The same tech worked on it every time and he was curious about finding it too. About the 3rd time, he told me the only thing that might be the problem was a security system control module or something like that. If I remember right, it's about 3/4" x 4" x 6". It was located up under the radio area. Been almost 1 year and haven't had the problem since (KNOCK ON WOOD). One thing to do, turn your iginition switch on to run the fuel pump but don't start it. Watch the lights on your dash to go out. If the security system light stays on after all the others go out, you have a security system problem. I can't say this is your problem, but it sure was mine. Hope this helps.

Thanks for the reply's. I took it to a dealer and they came up with three fault codes but wanted another hour to access it. After watching my truck sit there for 15 min. with out anyone looking at it and already $90 for an hour I gave up. My gut feeling is it's a faulty module some where.

Sounds like my problem is similar to Deepee's. The other day, I needed a tow since the Sierra would not start at all and the security light was lit. My garage checked it out and discovered a loose connection on the security module. I'm hoping that this was the source of my other intermittent starting problems.