1989 Chevy S-10 Fuel Pressue Regulator Diaphragm

Pressure regulator is number 6 and 7 in the picture. For model 700 TBI. Also, when you replaced the fuel pump if there was a pulse dampener between the pump and the tank unit, it should be removed and replaced with a piece of fuel injection hose.When the dampeners go bad they will cause pressure issues

What you've been hearing is all true

The pressure regulator is a diaphragm-operated relief valve with system operating pressure on one side and and atmospheric pressure on the other side. The function of the regulator is to maintain a constant pressure to the injectors at all times, by controlling the flow in the return line by means of a calibrated bypass.

NOTE: The pressure regulator on this unit is serviced as part of the fuel meter cover and should not be disassembled.

Regulator-1994-97 I engines

1. Properly relieve the fuel system pressure and disconnect the negative battery cable.
2. Remove the fuel return pipe from the regulator and discard the old O-ring.
3. Disconnect the vacuum hose from the regulator.
4. Remove the fuel return pipe clamp.
5. Remove the pressure regulator attaching screw, then remove the regulator and discard the O-ring.

Use a wrench to unfasten the fuel line-to-regulator fitting

Disconnect the vacuum hose from the regulator

Remove the pressure regulator attaching screw

Remove the regulator from the manifold and discard the O-ring

To install:

6. If the old pressure regulator is being installed, check the filter screen (if equipped) for contamination and replace, if necessary.
7. Lubricate the new O-rings with clean engine oil, then install them on the pressure regulator and fuel pipe.
8. Install the pressure regulator onto the manifold.
9. Make sure the regulator attaching screw threads are covered with Loctite  262 or an equivalent threadlocking compound, then install and tighten the screws to 31 inch lbs. (3.5 Nm).
10. Connect the vacuum hose to the regulator.
11. Make sure the new O-ring is in position, then connect the fuel return pipe to the pressure regulator and tighten to 22 ft. Lbs. (30 Nm).
12. Install the fuel return pipe clamp and attaching nut to the lower intake manifold assembly.
13. Connect the negative battery cable, then pressurize the fuel system by cycling the ignition (without attempting to start the engine) and check for leaks.