Alright the truck i have in my sig. is cutting out at high rpm's. Less than a week ago the truck would run great all the way up to 3,500 rpm's and now it cuts out at about 2,800 and above. The pump is set up to run at 3,500. It sounds like it is sucking air or the timing has slipped a little bit. What do you all think it could be?

 

Low fuel pressure?

 

Fuel pressure is good i checked it last night.

 

Welcome to the wonderful world of high rpm popping 12 valves.
https://www.dieseltruckresource.com/...t=high+popping
Hopefully you will have better luck than me, 2 years and still popping

 

mine was poping ,, after installed the fass ,, i had two pickups factory and the drawstraw ,, found out its air i was sucking the plastic tube closed in the tank (factory pickup),,, took that off no more popping ... hope it helps

 

I got it fixed last night turned out to be one of the little screws the hold the thermostat for the fuel heater came loose a little bit.