Low fuel pressure

Good morning,

Did you flush the tank of all the old fuel? Sitting that long, the fuel is no good and must be changed.

If the pressure is that low, the pump is the issue. The new pump may be loaded with dirt and debris from the old fuel in the system.

As far as the injectors, good chance they are the issue as well because all the dirt and debris could be up there as well.

https://www.2carpros.com/articles/how-fuel-injection-systems-work

Roy

Injector cleaner, the additive, has no effect at all on the injector.

I would remove the injectors and have them cleaned or replaced.

Roy

REMOVE
Disconnect negative battery terminal.
Relieve fuel system pressure. (Refer to Fuel Delivery / Service and Repair.
See: Fuel Delivery and Air Induction > Procedures
Intake manifold plenum.

NOTICE: Use care in removing injectors to prevent damage to the electrical connector pins on the injector, and the nozzle. The fuel injector is serviced as a complete assembly only. Since it is an electrical component, do not be immerse it in cleaner.

Fuel rail assembly.

DISASSEMBLE
Injector retainer clip.
Discard retainer clip.
MPFI injector assembly.
Injector O-Ring seals from both ends of injector and discard.

CAUTION: Each injector is calibrated for a specific flow rate. When replacing fuel injectors, order replacements with the identical part number as the old injectors.

ASSEMBLE
Lubricate new injector O-Ring seals with engine oil, and install on injector assembly.
New injector retainer clips on injector assembly.
Position open end of clip facing injector electrical connector.
MPFI injector assembly into fuel rail injector socket with electrical connectors facing outward.
Push in far enough to engage retainer clip with machined slots on rail socket.

INSTALL
Fuel rail assembly. Refer to Fuel Rail.

Inspect
Temporarily connect negative battery terminal.
Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten seconds. Again turn to the "ON" position and check for fuel leaks.
Disconnect negative battery terminal.

Intake manifold plenum.

Tighten fuel filler cap.

Negative battery terminal.

IDLE LEARN PROCEDURE
Any time the battery is disconnected, the programmed position of the Idle Air Control (IAC) valve pintle is lost, and replaced with a "default" value. To return the IAC valve pintle to the correct position, perform the following procedure:

Restore battery power.
Connect Tech I "Scan" tool.
Select "IAC SYSTEM, " then select "IDLE LEARN" in the "MISC TEST" mode.
Proceed with idle learn as directed.

This procedure allows the Electronic Control Module (ECM) memory to be updated with the correct IAC valve pintle position, for the vehicle, and provide a stable idle speed.

Try this:
* Connect your fuel pressure gage to the fuel rail.

* Unplug the vacuum hose that goes to the Fuel Pressure Regulator. (The fuel pressure regulator is located under the intake plenum - it should be possible to locate the vacuum line that runs to it. Since you can't get to the fuel pressure regulator with the intake in place, follow the vacuum line to its source and unplug it there.)

* Start the engine to see if the fuel pressure goes higher than the 10 psi you reported (it should).

* If it goes to normal or near normal, then the Fuel Pressure Regulator is faulty and needs to be replaced.

*****
If you need to replace the Fuel Pressure Regulator, this is the procedure.

To replace the fuel pressure regulator on a 1987 to 1990 Chevy Celebrity with 2.8L/3.1L engine:

1. Remove the air duct from the throttle body.

2. Remove the two bolts that hold the throttle body to the plenum and move it slightly aside. You do not need to remove the throttle body from the engine.

3. Remove the nuts that hold the EGR valve to the plenum along with the vacuum line. Move the EGR valve aside, it does not need to be removed from the engine.

4. Remove the seven bolts that hold the plenum to the intake manifold.

5. Lift the plenum off of the intake manifold. Be careful to move the plastic vacuum lines out of the way without breaking them.

6. Unplug the vacuum line from the pressure regulator.

7. Remove the two fuel lines from the pressure regulator and move them aside.

8. Remove the two screws that hold the pressure regulator bracket from each fuel rail. Remove the two screws that hold the rails in place from each side.

9. The fuel rails can now be moved away from the regulator. The "O" rings may be stuck and require some force to pull them out of the fuel rails.

10. Remove the two screws that hold the bracket to the fuel pressure regulator.

11. The fuel pressure regulator should now be loose. There are four fuel connections, two on each side. One on each side is larger, the "O" rings often stick in their bores in the fuel rail, remove them from the fuel rail if they are stuck there. The other two connecting fittings have two "O" rings each. Sometimes they stick in the fuel rail, sometimes in the regulator. If they stick in the regulator remove them for use with the new regulator.

The new fuel pressure regulator should come with replacement "O" rings. A dab of oil on each will make re-assembly easier.

Re-assembly:

Reattach the bracket to the fuel pressure regulator. With the new "O" rings in place on the regulator slide the fittings into the fuel rails bringing them back in place. Put the screws that hold the bracket back in place and put the four screws that hold the fuel rails back in place.

Re-attach the fuel lines and the vacuum line to the fuel pressure regulator.

Using fresh gaskets put the plenum back in place, route the vacuum lines back in place. Re-attach the EGR valve and the throttle body along with the air duct from the air filter to the throttle body.

You are welcome.

We are always glad to help.

Roy

Yes, I do. As I stated in my first response, dirt or debris could have got in the new pump and is causing the low-pressure issue.

The simple answer is yes, you need a new pump. Look in the tank for any debris or dirt at the bottom.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Roy

You are welcome.

Always glad to help.

Roy

Was there a code for the sensor?

You could try that as it was a very common failure for that year.

Roy

Okay, try the sensor. If you get one, get a AC/Delco from your supplier.

Roy

You could but I doubt it has anything to do with your issue.

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

Roy

Okay, let us start with the fuel pressure. Can you tell me the fuel pressure?

No to the mass air flow and the O2 sensor. They will not cause this issue. If they did, they would code.

Roy

Sounds good. Let us eliminate a fuel pressure issue before we move on to the next step.

Roy