'96 4X4 xlt (auto locking hubs)
5.0 liter

Symptoms:
Truck turns over, but doesn't fire up.
Doesn't happen all the time (intermittent and random).

Details:
Truck always turns over, but doesn't start, here's what happens when it doesn't play nice... I put key in ignition, and turn to "run" position (position of key when driving. i know you know). I wait, and listen carefully. After a few minutes (from 2 min to 40 min), I hear a quick buzz sound. Then, truck fires up. Again, this happens sporadically... i'll go a month with no problem, then it misbehaves. (edit) Also, the problem occurs no matter which fuel tank I have switched on.

Also, it shuts off in the middle of driving every now and then. I know this is related, because when it does, and i pull over, i have to wait to restart it as described above.

Things i've tried:
Replaced fuel pump relay (two seperate tanks)
Replaced EEC relay
Replace ignition switch

Any ideas/help is greatly appreciated!

 

I'm not sure this is your problem but both my fuel pumps took a dump at the same time.Is the "quick buzz" a fuel pump,where is it coming from front or rear of truck? Need more info.

 

Dyna, thanks for the response! I have attempted to locate the buzzing sound many times (lasts about 1 second), but have been unsuccessful in pinpointing it. Even worse, I should be able to identify what it is just by the unique sound it makes, but i'm not that good. I'm assuming it is the fuel pump pressurizing, making the buzz. By the way, I've had this problem for about 8 months. Someone told me that fuel pumps, when failing, don't last more than 1 or 2 runs before going completely out. If both my pumps were failing, could they last this long? Or, could it be something else?

 

When it gets in a no start mood, I would check to see if you are getting spark through the spark plug wires while cranking the engine. Then you'd know if it was an ignition problem or a fuel delivery problem. You would need an assistant or the proper equipment to do this.

There are three ignition components that like to do what you're describing. The coil, the ignition module, and the PIP in the distributor. I have no idea what that buzz sound you have to wait for is either.

 

Take the truck to an auto parts store that will check for any codes that have been thrown for free. You may have to call around to see which stores will do it for free. I had a bad fuel pump last 7mos. b4 I changed it and it was still running when I pulled it.