[TSOJOURNER]

Knocking

Have you tried changing the fuel filter(s)? When was the last time you changed them? I get knocking when the filters start to get clogged up.

 

[TSOJOURNER]

My 2GM20 knocked its head off when it wanted me to bleed it. Seasonally it would let a little (very little) air into the line.

But me? I'd change out the injector valve. I really would. Change it out, bleed it, and sally forth.