Where is fuel pressure regulator located on 97 Toyota Avalon XLS. It was not found

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1997 toyota avalon xls. Can't find fuel pressure regulator on the engine. It was not found at the end of the fuel rail by visual search. The car cranks but cuts off after 3-4 seconds. Already replaced fuel filter and pump. Still the same problem. When starter fluid was applied the car ran longer. Seems like fuel delivery issue. Don't have adaptable fuel pressure kit. Dealer says it's a return fuel system and regulator is on engine. What would you do next.