Momentary power lost

[tim0]

Truck seems to shut off for a split second while climbing very steep grades. Fuel tank level does not seem to affect the loss of power. All instruments stay normal except the tach which drops until power is regained. 110,000 miles. Happened with original fuel filter mounted pump and with the newly installed Fass pump. Other than this problem, truck runs great. No codes.The best way to describe the problem is it’s like I turned the key off then right back on. Any ideas appreciated.
‘03, HO, 48re

 

[Mark31]

My sig truck does it every year or so, mostly shortly after a "complete stomp-it-down" fill up. It sometimes sets a code (maybe 0721?) that says a bunch of vague mumbo jumbo that could be any number of things. Light goes out after 3 run/off cycles. It will have to get worse before I lose any sleep over it.

 

[cerberusiam]

How steep of grade? 45degrees or more or just normal roads. Is the engine shutting off or just loosing power? How did you do the FASS install? Did you use the factory canister or install a bulk head fitting? What size pickup lines from the tank?