Keep in mind that you have several components there:
- Fuel Pump Sender Assembly,
- Fuel Pressure Regulator,
- Fuel Rail Assembly, and
- Fuel Injectors.
1.- Fuel Pump (Sender Assembly) - TESTING
Refer to the accompanying charts for fuel pump diagnosis and testing.
The fuel injection system remains under pressure, even after the engine has been turned OFF. The fuel system pressure must be relieved before disconnecting any fuel lines. Failure to do so may result in fire and/or personal injury.
Fig. 3.1L engine OBD system check to be done before fuel pump
relay circuit diagnosis
Fig. 3.1L engine fuel pump relay circuit diagnosis (1 of 2)
Fig. 3.1L engine fuel pump rela2000 Malibu Starts then looses - db78a73.jpgiagnosis (2 of 2)
Fig. View of the fuel pressure test port (Schrader valve)-3.1L
engine
A - 3.1L engine fuel system pressure test (1 of 4)
B - 3.1L engine fuel system pressure test (2 of 4)
C - 3.1L engine fuel system pressure test (3 of 4)
D - 3.1L engine fuel system pressure test (4 of 4)
Fig. The fuel pump/fuel sender module assembly is mounted in the
fuel tank
2.- Fuel Pressure Regulator - REMOVAL & INSTALLATION
(the fuel pressure regulator, which is
located on the fuel rail assembly)
NOTE: Before removing the fuel regulator assembly, place a clean
shop towel under the regulator to catch any fuel drips
To install:
WARNING
The fuel return pipe must be connected before tightening the
regulator retaining screw to prevent the regulator from rotating.
Rotation of the regulator could damage the retainer and spacer bracket
and lead to a fuel leak at the regulator inlet.
continue...
3.- Fuel Rail Assembly - REMOVAL & INSTALLATION (3.1L Engine)
Fig. View of the fuel rails (1 and 5), injectors (4) and fuel
pressure regulator (3)-3.1L engine
Properly relieve the fuel system pressure, then disconnect the
negative battery cable (if not done already).
Remove the intake manifold plenum (upper intake
manifold) as outlined in
.
Unfasten the fuel pipe bracket bolt, then remove the fuel pipes at
the rail.
Remove the fuel pressure regulator from the fuel rail.
Remove and discard the fuel feed and return pipe O-rings.
Detach the fuel injector electrical connectors.
NOTE
Be careful when removing the fuel rail assembly to avoid damage to
the injector electrical connector terminals and spray tips. Prevent
dirt and other debris from entering open lines and passages. Fittings
should be capped and holes should be plugged during servicing.
If applicable, disconnect the coolant temperature sensor wiring.
Unfasten the fuel rail retaining bolts, then remove the rail
assembly from the engine.
Remove and discard the injector O-ring seals from the spray tip
end of each injector. With the O-rings removed, the O-ring backup may
slip off the injector. Keep the backup for reuse during installation.
To install:
Make sure the backups are on the injectors, then lubricate new
injector O-rings with clean engine oil and install on the spray tip of
each injector.
Install the fuel rail in the intake manifold. Tilt the assembly to
install the injectors. Secure with the retaining bolts, then tighten
the bolts to 7 ft. lbs. (10 Nm).
Attach the injector electrical connectors.
Put new O-rings on the fuel feed and return pipes, then install
the pipes. Using a backup wrench on the fittings to prevent them from
turning, tightening the fuel pipe nuts to 13 ft. lbs. (17 Nm).
Install any remaining components.
Connect the negative battery cable, then tighten the fuel filler
cap.
Turn the ignition to the
ON
position for two seconds, then turn it to the
OFF
position for ten seconds. Turn again to the
ON
position and check for fuel leaks.
Install the intake manifold plenum.
4.- Fuel Injectors - TESTING
The easiest way to test the operation of the fuel injectors is to listen for a clicking sound coming from the injectors while the engine is running. This is accomplished using a mechanic's stethoscope, or a long screwdriver. Place the end of the stethoscope or the screwdriver (tip end, not handle) onto the body of the injector. Place the ear pieces of the stethoscope in your ears, or if using a screwdriver, place your ear on top of the handle. An audible clicking noise should be heard; this is the solenoid operating. If the injector makes this noise, the injector driver circuit and computer are operating as designed. Continue testing all the injectors this way.
CAUTION
Be extremely careful while working on an operating engine, make sure you have no dangling jewelry, extremely loose clothes, power tool cords or other items that might get caught in a moving part of the engine.
All Injectors Clicking
If all the injectors are clicking, but you have determined that the fuel system is the cause of your driveability problem, continue diagnostics. Make sure that you have checked fuel pump pressure as outlined earlier in this section. An easy way to determine a weak or unproductive cylinder is a cylinder drop test. This is accomplished by removing one spark plug wire at a time, and seeing which cylinder causes the least difference in the idle. The one that causes the least change is the weak cylinder.
If the injectors were all clicking and the ignition system is functioning properly, remove the injector of the suspect cylinder and bench test it. This is accomplished by checking for a spray pattern from the injector itself. Install a fuel supply line to the injector (or rail if the injector is left attached to the rail) and momentarily apply 12 volts DC and a ground to the injector itself; a visible fuel spray should appear. If no spray is achieved, replace the injector and check the running condition of the engine.
One or More Injectors Are Not Clicking
If one or more injectors are found to be not operating, testing the injector driver circuit and computer can be accomplished using a "noid" light. First, with the engine not running and the ignition key in the OFF position, remove the connector from the injector you plan to test, then plug the "noid" light tool into the injector connector. Start the engine and the "noid" light should flash, signaling that the injector driver circuit is working. If the "noid" light flashes, but the injector does not click when plugged in, test the injector's resistance. Resistance should be between 11-18 ohms.
If the "noid" light does not flash, the injector driver circuit is faulty. Disconnect the negative battery cable. Unplug the "noid" light from the injector connector and also unplug the PCM. Check the harness between the appropriate pins on the harness side of the PCM connector and the injector connector. Resistance should be less than 5.0 ohms; if not, repair the circuit. If resistance is within specifications, the injector driver inside the PCM is faulty and replacement of the PCM will be necessary.
Hope helped.
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WHAT ABOUT A BAD FUEL PRESSURE REGULATOR AND A STOP UP FUEL FILTER.
POSSIBLE YOU COULD HAVE BOUGHT A DEFECTIVE FUEL PUMP.
ANOTHER THING YOU COULD HAVE A RESTRICTED FUEL LINE.
I thought that too so I replaced the fuel pump twice thats not it. there has to be something cutting the power to the pump
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I'm thinking oxygen or throttle body position sensors.. both of these control the air gax mix ratio .. in other words then send data to the cars computer telling it when to send more gas.. Its malfunctioning sending excessive gas which there isnt enough air for causing you to loose power.. To determine this have a diagnostic done on the car.. This will let you know which sensor is bad.. and replace it.. I'm also thinking that the sensor might just be sending wrong data in which case it may not show up in the diagnostic.. Ask you mechanic to have a look at both sensors and if he has a replacement you can try before having to buy them both!!
I have a fuel pressure tester hooked up and can see it is not getting fuel pressure and can hear the pump not running
just because you dont get an error code dont mean the sensors are not bad.. it controls the air fuel ration.. its giving back a false reading causing the brain to lower the fuel amount.. It will show show the sensors are wroking when they are infact not working propperly..
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it has a new fuel filter too
there are no codes being thrown and I have a fuel pressure gauge hooked up to the rail I can see it looses pressure and can not hear the pump running
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