the fuel pressure regulator is located behind the drive belt close to the top
where is the fuel pressure regulator on1991 lumina 3.1 /
If its like the 1993 Lumina it's in the fuel tank.
Low fuel pressure (fuel pump, pressure regulator, fuel filter), vacuum leak, partially blocked/fouled injectors.
Not real familiar with the vehicle and not much info to go on but my guess is possibly a faulty or damaged diaphragm in the "fuel pressure regulator", which is located where the return to tank fuel line connects to the large metal fuel line that the injectors are connected to or "fuel-rail", . That is the only link between fuel system and vacuum system in a fuel injected engine that I can think of.
the fuel pressure without vacuum is 34psi. and with vacuum 43psi.
ask a mechanic to do it for you
If it is a 3.1 9-13 psi.
Stock base fuel pressure is 42 psi. This is the pressure when the vacuum hose is removed from the fuel pressure regulator. The vacuum hose must be plugged when its removed from the regulator.
It doesn't have a vacuum line attached to the fuel pressure regulator.
There is a vacuum controlled pressure regulator on the fuel rail. Check for vacuum leaks. If the unit is faulty, it will often leak fuel into the vacuum line.