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If your talking about the fuel pump, there is no shut-off switch. If your sure it is the fuel pump, check the fuel pump wiring for voltage and ground, engine cranking. Gray wire is voltage, black is ground. The pcm B fuse is in underhood fuse block. If good voltage and ground at the fuel pump with no fuel pump action or fuel pressure, suspect the fuel pump.
Ran a hot wire to what fuel pump or the control module ? Which of these is yours ?
Figure 9: Fuel Controls - Fuel Pump Controls (LY6)
Figure 10: Fuel Pump Flow Control Module (Except LY6) Does yours have fuel pump flow control module under the vehicle Fuel Pump Flow Control Module (except LY6)
Mounted to the left side of the frame assembly below the driver seat ?
Fuel Pump Flow Control Module (FPCM) - LMF
The fuel pump flow control module (FPCM) is a serviceable GMLAN module. The FPCM receives the desired fuel pressure message from the engine control module (ECM) and controls the fuel pump located within the fuel tank to achieve the desired fuel pressure. The FPCM sends a 25 KHZ PWM signal to the fuel pump, and pump speed is changed by varying the duty cycle of this signal. Maximum current supplied to the fuel pump is 15 amps. A liquid fuel pressure sensor provides fuel pressure feedback to the FPCM.
Electronic Returnless Fuel System (ERFS) - LMF
The electronic returnless fuel system is a microprocessor controlled fuel delivery system which transports fuel from the tank to the fuel rails. It functions as an electronic replacement for a traditional, mechanical fuel pressure regulator. A pressure vent valve within the fuel tank provides an added measure of fuel pump flow control module (FPCM). Desired fuel pressure is commanded by the engine control module (ECM), and transmitted to the FPCM via a GMLAN serial data message. A liquid fuel pressure sensor provides the feedback the FPCM requires for Closed Loop fuel pressure control.
If your vehicle has this system check it for DTC'S - diagnostic trouble codes . Will take guess work out of it .
DTC P0191: Fuel Rail Pressure (FRP) Sensor Performance
DTC P0192: Fuel Rail Pressure (FRP) Sensor Circuit Low Voltage
DTC P0193: Fuel Rail Pressure (FRP) Sensor Circuit High Voltage
DTC P0230: Fuel Pump Relay Control Circuit
DTC P0231: Fuel Pump Control Circuit Low Voltage
DTC P0232: Fuel Pump Control Circuit High Voltage
DTC P023F: Fuel Pump Control Circuit
The engine control module (ECM) supplies voltage to the fuel pump flow control module (FPCM) when the ECM detects that the ignition is on. The voltage from the ECM to the FPCM remains active for 2 seconds, unless the engine is in crank or run. While this voltage is being received, the FPCM supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.
DTC P025A: Fuel Pump Control Module Enable Circuit . Ford Electronic Returnless Fuel System Diagnosis Part 1 this for ford but the GM system works the same . You'll need a wiring diagram so you know what wires are what . Free wiring diagrams http://www.bbbind.com/free_tsb.html
Check voltage and ground at fuel pump, pink wire is voltage black wire is ground. The initial prime is only for key on engine off, lasts a couple seconds. You use a testlite to check voltage and ground.
Check voltage and ground for fuel pump relay. Also, you have an inertia switch, you have to check that.
For testing, you can use jumper wire at load side of fuel pump relay, the load side is that line with the arrowhead. When relay is energized that line moves to the other terminal and sends voltage to fuel pump, just unplug the relay, use jumper between terminal 30 and 87, terminal 30 is hot all the time.
The voltage and ground for the control side of relay is controlled by computer I believe, If the control side is the problem, I'd have to check wiring circuit and computer.
With engine cranking, you have injector pulse, also?
You said you jumped the wires for the pump? Was that at the pump relay?
If you have a voltmeter or test light, keep the jumper wire in place and check for voltage at the fuel tank connector. The pump wire will be gray. With relay out and jumpered there, you should have battery voltage at the fuel tank connector. The key doesn't even have to be on, cause the relay has voltage to it at all times. If you jumpered it right (terminals 87 and 30 on the relay), and no voltage at the tank connector, you have a broken fuel wire somewhere between the relay and the fuel tank.
If you do have voltage at the tank, but the pump still won't work, only two possibilities, a bad pump or the ground for the pump is lost. Check the pump ground first.
You probably have had this fixed already. Using voltmeter check to be sure voltage is supplied to wiring at fuel pump(located under access under rear seat) If no voltage throught the wiring. Check hot to body ground anywhere. If voltage present you have a faulty ground. If no voltage again- try FUSE or track the wiring back to find a rub spot causing short. Taking for granted you checked pump before install to be sure it worked.
http://www.bbbind.com/free_tsb.html free wiring diagrams ! Enter vehicle info. year , make , model an engine size . Under system click on engine ,then under subsystem click on fuel controls . Then click the search button , then click blue link .The 7th diagram down shows two fuel pump relays , This I have not seen before ! One is speed cont. relay an the other is just fuel pump relay ? The speed control one has a resistor in the electrical circuit . That is way your droping voltage .
Fuel Pump Electrical Circuit Diagnosis (VIN K)
Fuel Pump Electrical Circuit Diagnosis (VIN 1)
The PCM alters fuel pump speed by energizing the fuel pump speed control relay. Under normal conditions, the fuel pump speed control relay is energized. The applied voltage to the fuel pump is controlled by a resistor assembly. When higher fuel volume is required due to increased engine load, MAP sensor value over 90 kPa the PCM de-energizes the fuel pump speed control relay circuit. The increased voltage to the in-tank fuel pump allows a higher volume of fuel to be delivered to the fuel rail. The PCM also compensates for low system voltage by energizing the fuel pump speed control relay.
Have it check for codes !
Did DTC P0230 or DTC 1260 set?
Go to DTC P0230 Fuel Pump Relay Control Circuit or DTC P1260 Fuel Pump Speed Relay Control Circuit
Go to Step 3
When you first turn on the key, no crank, the fuel pump should run for a few seconds then stop. There shows to be an oil pressure switch in parallel with the fuel pump relay. It's just a redundant power supply to the fuel pump. Once it cranks enough to bring up oil pressure and the switch closes, the pump will run even w/o the relay. Both the fuel pump relay and oil pressure switch get voltage from the ecm b fuse.
At the fuel pump connector, check voltage and ground, when problem is ongoing. Gray wire is voltage--black wire is ground.
You could pull the fuel pump relay, use jumper wire between terminals on load side of relay. The load side is that line with arrow head, when energized that line moves to the other terminal. As you can see, the orange wire is hot all the time, the gray wire carries voltage to fuel pump. If it runs with jumper, then check control side of relay, the control side has to have voltage and ground, dark green wire with white tracer is voltage comes from pcm. The black wire is ground.
Best thing to do is check voltage at fuel pump harness, have some one turn key on and off every 5 secon's, probe wire's at fuel pump harness, one of the wire's will have voltage for about 3 secon's, if you do fuel pump is getting voltage, some time while cranking engine and hitting gas tank with hammer at the same time, fuel pump will start working again, if it start's, you will still need to replace fuel pump or it will happen again, fuel pump is in fuel tank.
If your pump is running on 7vdc, you are not getting enough fuel pressure to sufficiently supply the engine with gas, and it will run rough, sputter, surge, backfire, all manner of unpleasant things. If this is the case, and you are reading 7vdc while the pump is connected, this could indicate a problem within the fuel pump or fuel pump electrical circuit. Turn the car off, unplug the fuel pump wire harness from the fuel pump, insert your voltmeter leads into the vehicle-to-fuel pump wire harness connector, then have a helper turn the key to "on." You will have two-three seconds before the computer senses no fuel pump return signal, and shuts off voltage to the fuel pump. Observe the voltage coming from the vehicle wire harness to the fuel pump connector, it should be 11-13vdc. If it is, and only drops to 7vdc when connected, there is a partial short in the wiring from the point the fuel pump plugs into the harness, or the pump just creates a large voltage drop. Every device causes a voltage drop while in use, but 5vdc is too much of a loss. Re-examine the fuel pump installation, and make sure there are no obstructions over the fuel pump inlet, and that the wire harness inside the tank is okay.
First of all you will only have voltage for 2 seconds after key is turned on from the fuel pump relay. after that when you begin to spin the engine over oil pressure then builds up and closes the contacts on the oil sending unit causing the fuel pump to stay powered up as long as it's spinning or it's crunk and running.
so while you check for power on the tan with white stripe at fuel pump , have someone bump the engine over, if you have power up until about 2 seconds after they let off the key then check ground to pump if it's ok then you'll need a fuel pump.
If you don't have voltage when it's spun over then check the red wire coming from the oil sending unit the same way you checked it at the fuel pump.
If you have voltage then check inline fuse beside the battery. if fuse is'nt blown then check for broken wire from there to fuel pump.
If you don't have voltage from red wire at oil sending unit then check for voltage on orange wire at sending unit, if you have voltage on the orange wire and not on the red wire while someone is spinning it over then replace the oil sending unit.
If you wanna do a quick check that makes sure your relay isn't the problem Go to your 12 way diagnostic connector under dash by stearing wheel. and touch a battery hot wire to pin G if relay is ok the you should hear the fuel pump come on.