99 Burb blows ECM1 fuse at turn of key

Newbie here. I searched but couldn't find anything about the ECM1 fuse on this forum.

My ECM1 fuse is blowing as soon as the key is turned to the on position. I've figured out that the ECM1 fuse powers the fuel pump relay. The fuel pump doesn't spin to build pressure after the fuse is blown so I thought maybe it was a short in the fuel pump. But then I noticed that the fuel gauge indicated I have a tank and a half of fuel when the fuse is blown! After putting a new fuse in, the fuse blows right away but I can hear the fuel pump build pressure (about 3 seconds of spinning) and the fuel gauge works for a few seconds. Again, this is after the fuse blows -- I went through 10 fuses in about an hour trying to troubleshoot.

I checked the fuel pump relay and it appears to be working properly. Here's the kicker: I pulled the fuel pump relay and the ECM1 fuse still blows as soon as the key is in the on position. I'm thinking it can't be the fuel pump then.

Any thoughts/ideas/experiences are appreciated. Thanks!

Welcome to AF.
What size burp and what engine ?
ECM1 powers the injectors and PCM/CCM.
Unplug injectors to start with and see if fuse blows.

The ECM-B fuse powers the fuel pump thru the pump relay.

The ECM-1 fuse powers the VCM/PCM, Crank Position Sensor, Ign Control Module, Ign Coil & fuel injectors.

It could be any one of these components or a chaffed wire shorting to ground.

Hey, thanks for the replies. Dang electrical problems!!

For MT-2500, I have a K1500 -- 5.7L Vortec, 4WD.

OK, got lucky w/an easy fix and was only out the cost of the tow:
Back when I had to replace my intake manifold gaskets (second time, that is), I didn't put the harness that goes from the throttle body to the front of the motor back in it's clip. The harness shorted against my exhaust manifold on the passenger's side. A couple of minutes w/my multimeter on continuity testing and some movement of the harnesses in the engine compartment and the sound stopped. I still need to look into the damage to the wires, but the burb is back running!

Also, for those that need to replace the intake manifold gaskets, I highly recommend the metal intake manifold gaskets that Felpro has out now. They came in a kit. The plastic ones are nice but only lasted a year and a half. And make sure to mark the position of the distributor before removing it to make reassembly easier.

Thanks for posting back how it went.
Glad you found the problem and yes get them wires fixed.

10-4 on the felpro rubber metal backed gaskets.
One of the few times OEM is not so good.
MT