[okmech1]

I had a very similar problem, I think i had a P0440, and also tried to understand the system before I started troubleshooting. The problem I ran into was I would have had to spend a couple hundred on a diagnostic code reader to really test it out. I opted to bring it to a mechanic that knows isuzus well and found that my seal between the fuel tank and pump was leaking. Sure enough, when I removed the pump to replace the sending unit, I pinched the seal.

Not to say this is your problem, but I found it was cheaper to get a quality professional diagnosis, and pulled out less hair.

Did the hose wind up fixing it though? Are you able to view the code and verify it is only 0442 coming on?