truck sounds like a diesel? GMC sierra?

[Derek Snowfall]

replaced my fuel relay fuse because my gas pedal was hesitating, crappy tire guy said fuel relay just turns the fuelp pump off/on thats it. well i doubt his profession since my truck now sounds like a diesel and he says he doesnt know why. The new fuse did give me MORE power which was my intention so im happy but uneasy about hearing this diesel sound.

i cleaned the prongs on my old one and put it back in. run crappy no diesel noise. put back in the new fuse and works better but diesel sound.

 

[2001 GMC Sierra]

What year is your Sierra and which engine does it have? My '01 Sierra with the 5.3L engine has piston slap (which is a widely known problem). Apparently the early 5.3 pistons had shorter piston skirts and make noise like a diesel for a minute ot two after starting. Mine has done that for over 100-k miles, so I don't think it's causing any damage... Ron