There was an old TSB on fuel pressure at WOT that dealt with this little problem at the assembly plant.
Seems that the lower clamp was a little difficult to get over the neck in the tight spaces so they just put it on the hose above the barb.
When both pumps were under full load the pump with no clamp would blow fuel right back into the fuel supply causing cavitation and reversion. The engine would stumble than pick right back up.
Guess what the repair fix for the problem was?
Fix:
Drink fewer than 8 beers during 10AM morning break and put the friggin clamp in the right place. Live better drink union....