Why is there no power going to my fuel pump? I've changed the relay, fuses, down to the PCM and still have nothing. I jump from #30 to #87 at the fuel relay spot in the underhood fuse panel and can hear the pump working. But not when I put the relay back in and turn on the key. '02 Chev. Silverado 4.3 V6. Truck just doesn't start. I've tested all circuitry related to fuel, changed the relay, ECM b fuse etc. nothing helped.

You need an electrician. He will probably need a wiring diagram to figure out what circuit has the malfunction. Have you checked to make sure the fuel pump fuse has not blown?
By jumping the solenoid, do you mean you bypassed it? I don't even know what solenoid you are referring to.
The pump circuit, if like other GM vehicles of those years, probably has a fuel pump relay (under the hood) and a fuel pump fuse- probably a 15 amp blue fuse, could be under the hood or under the dash. If you check all fuses, then find the pump relay, now you can check there for power available to the relay. The pcm is what signals this relay on. Does your pcm have power? Does your check engine light come on when you turn the key to ON?

The PCM is likely doing its job. Reading the error codes from the OBDII system is the first step. When you are removing power it is likely you are resetting the codes.

The fuel pump can be disabled from the PCM but also from the SRS Airbag Computer Control Module. In the event of an accident the fuel pump is disabled to prevent fuel escaping.

Automatic Shutdown Relay (ASD) is the key. This relay is activated when you initiate start and controls power to fuel pump, ignition and fuel injectors. If the key switch, air bag saftey system or any thing in line with this circuit including the PCM trips the relay the fuel pump stops.

The ASD relay is under hood and mounted in an accessible power distribution box. Swap this relay with another identical to see if this relay is defective.

Hope this helps?

Do you know what a fuel pump relay is ? You can check B+ Voltage an control at the relay > Find the relay in the under hood fuse box . Pull the relay out an look on the bottom , you should see four sets of numbers 30,87 an 85,86 ! 30 an 87 are the power side ! One of these will or should have B+ voltage , the other goes to the fuel pump . You could take a piece of wire an jump 30 an 87 , in the fuse box where the relay plug's into . The fuel pump should run ! The control side 85 an 86 , one will have B+ voltage an the other will be open circuit , unless you crank the engine ! The PCM supplies a ground when an input from the crank sensor is sensed. Videos on youtube on trouble shooting an testing fuel pump electrical circuits .

Is the PCM - engine computer energizing the fuel pump relay ? The best place to test the fuel pump electrical circuit is at the relay , using a test light or volt meter were the relay plugs into. On the bottom of the relay there should be numbers 30,87 an 85 an 86 . 87 an 30 are the fuel pump side of the relay . 85 an 86 are the control or turn on side of the relay . Two of the pins should have B+ voltage . One will be open an the other will show ohms resistance on ohm meter . Find a wiring diagram at http://www.bbbind.com/free_tsb.html an test for power an control of the relay . Test don't guess an don't be a parts changer , Fuel Pump Electrical Circuits Description and Operation

Did you check for voltage at the relay socket before replacing the relay ? Most relays have four or five pins , two should have battery voltage , one goes to the fuel pump an the last one is a ground supply from the PCM - powertrain control module - engine computer if you know what that is . If you look on the bottom of the relay it should have some numbers 85,86 , 30,87 ! 30 an 87 are the fuel pump side . 30 is battery voltage for the pump ! 85 is battery voltage an 86 is ground from PCM . VEHICLE RELAYS Operation Diagnosis Before replacing wiring harness test ! Check out these videos... Fuel Pump Electrical Circuits Description and Operation

The fuel pump power to the relay is powered by the PCM BAT fuse 15amp.
The relay is grounded and the PCM powers the relay to turn it on and power the pump.
You should have power on the orange wire with the key on.
The PCM powers the relay when the key switch is in the start position and after the computer sees oil pressure and RPM.

The PCM does not supply the voltage to the fuel pump . All the PCM does is energize the fuel pump relay ,closing contacts in side the relay which connects the fuel pump with a B+ voltage supply from Fuel pump fuse 15amp location , under hood fuse box . You have a high resistance problem in the wiring to the fuel pump . bad connection , corrosion etc... Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia

The fuel pump wires are positive: pink/black and negative=black. Pull the connector, turn the key on, and check these with a test light. Your pump power runs through the PCM.

check the pcm ignition fuse and the fuel pump injectors fuse.if all is good.your pcm could be the problem. the pcm it controls fuel pump.first have car hooked up to scanner to look for pcm failure code.

how did you jump the fuel pump relay, by bypassing the relay or by applying power to contact that closes the relay? If you bypassed the relay completely you need to b ench test the relay you can do this easily by using any 12v dc power source. If you tested the fuel pump relay by applying power to the relay and the pump run and developed pressure. I suspect a wiring or ground issue. Good luck