Need help Cummins ISX

Ok guys here is the story. I purchased a Peterbilt about a month ago. Last week few codes pops up for fuel pressure and truck started to loose power, I stopped by Peterbilt dealership in Idaho and they told me there is some issues with fuel pump and it will take about 4 or 5 days to fix it because that was a Friday and they were closed on weekends, so I decided to go back to Chicago and take care of it while I will be at home. On my way truck started to loose power really bad and I towed it to Peterbilt in Dickinson ND and told them that there is probably fuel pump failed (codes for fuel pump were active), they checked a truck and found that turbo was bad, they replaced a turbo, erased all codes and told me that truck is fine and I'm good to go (cummins paid for that by the warranty) 300 miles after I left their shop engine failed, I towed it to another peterbilt in Alexandria MN, they checked it and told me that fuel pump is failed and pieces of metal from that went to the engine and killed the engine and now I need a new engine (which cost 40k $) and Cummins won't pay for that since fuel pump not covered by the warranty and engine failed because of the fuel pump. How is that possible peterbilt's cummins certified mechanic just checked it a day before that and told me that everything is fine and all codes for fuel pump were because of turbo?? How to make them pay for that? Should I hire a lawyer or try to contact cummins first? I don't have any money to pay for that, and dealer just checked it right before the engine failed. Please give me advise what should I do now. Thank you

 

That's a 2012 Pete with 370000 miles by the way

 

Thank you. Where I can find if that's CM2250? There is a Part # RTL016913A and Serial Number 79556729

 

Yes but I stopped by another dealer before pump failed and and they didn't see the problem, they let me go and told me that all codes for the fuel pump were caused by the turbo...that's caused whole engine to fail later

 

I even told them that there is problem with the fuel pump when my truck got there (all my phone calls are recorded so I have a proof I told them that), and they didn't do anything about it anyway

 

Dealer told me that metal shavings from the fuel pump went to the engine and caused engine to locked up. But there was an antifreeze in the engine and I think that's caused hydro lock on it