GMC Repair: 2003 yukon xl 5.3pcm b fuse and b/u lp fuse, 2003 yukon xl, yukon xl

Question
I keep blowing out the pcm b 20a fuse and the b/u lp 20a fuse on my 2003 yukon xl,when i try to start up. Yukon stays on till the 20a fuses burn (30 seconds) max. i replaced fuses along with the starter relay in same fuse box.

Answer
Hi
I have run into this a few times, USUALLY if the PCMB fuse is blowing, the In Tank Fuel pump is the culprit.
As far as the B/U fuse, I would look at the bulbs especially in the rear.
Possible the wiring leading up to the bulbs (poor after market tie in's) etc, could also be blowing this fuse.