1998 Blazer LT 4.3 L V6 No power to fuel pump relay on the relay trigger circuit at any time. Power is there for the fuel pump power circuit if the power was there to trigger the relay New fuel pump installed

The relay is under the hood in the power dist. box, the cut off switch is located in the side panel in the rear cargo area

If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_4c166ba81493f541

Maybe a problem in the fuel pump circuit. Check fuel pressure with engine off, and key turned to on, not start. If no pressure, diagnose the pump circuit at the fuel pump relay. One terminal for the relay would be the power feed for the pump. The engine computer signals the relay on for 2 seconds with key on to prime the system, also signals during engine cranking.

I don't think you can on that vehicle-probably not a code, anyway. Check the fuel pump relay, it may be stuck on. Should be located in the power distribution box under hood. Pull it out-pump should stop-swap in a different relay to test. If pump still runs on with new relay, the wiring to the relay needs checked.

Power is fed to the pump by a fuel pump relay. The relay is powered by a fuse but is triggered by the computer. So when you turn the key on, the computer triggers the relay, the relay closes and turns on the fuel pump. Power is cut off only when the key is shut off and the computer kills the trigger signal to the relay

try testing the power in and out to the relay take out the relay and check what you have going on there if you got nothing you got other issues if you do have power at the relay then your pump is probly shot.

For the 1998 Chevy Blazer 4.3L V6:

Firing Order:
1-6-5-4-3-2

Cylinders:
......(back)......
|..6..|.......|..5..|
|..4..|.......|..3..|
|..2..|.......|..1..|
......(front)

Distributor Connections:
...........(back)
Coil-> o
6-----> o.......o <-----5
4-----> o.......o <-----1
2-----> o.......o <-----3
...........(front)

Let me now if this helped, or if you have additional information or questions. Feel Free to contact me at FixYa.com!

Your fuel pump relay is triggered by your oil pressure switch,try jumping across to bypass your fuel pump relay if truck runs then figure out why relay is not being triggered.

Check your Automatic Shutdown Relay in your fuse and relay box under the hood by the battery. The power supplied to the fuel pump, ignition coil, fuel injectors,  and parts of the power module is controlled by the logic module through the Automatic Shutdown Relay (ASD); the idea is to shut off fuel pressure and the ignition systems when the key is turned off to prevent fires, dieseling, and other problems.
The ASD relay is closed (allowing power to flow through it) when the ignition is first turned on. If the signal from the ignition reference is lost while the engine is running, the logic module cuts power to the ASD, which in turn removes power from the fuel pump, ignition coil, injectors and those parts of the power module.  This causes the engine to shut down.

The logic module monitors the relay driver.  If it senses that the relay driver is not responding correctly it will trigger a code. If the logic module does not sense an absence of current when the circuit is open, or 12 volts DC when the circuit is closed, it knows that the circuit is open or shorted, and triggers code 42. Failure of the automatic shutdown relay is often shown as inexplicable stalling or refusal to start. Good luck and hope this helps lead you in the right direction. Hint: The ASD can be triggered by a broken wire or short in another place, e.g. the fuel pump. 

P0230 The power train control module (PCM) provides ignition positive voltage to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the PCM energizes the fuel pump relay, which applies power to the fuel pump. The PCM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the PCM de-energizes the fuel pump relay after 2 seconds. The PCM monitors the voltage on the fuel pump relay control circuit. If the PCM detects an incorrect voltage on the fuel pump relay control circuit, DTC P0230 sets.
Check the voltage of the battery, and check the fuel pump relay. You can try swapping the relay with another relay like the A/C relay for now and see if the check engine light (MIL) goes away. The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. Good luck and hope this helps. Keep me posted, be glad to help.

I have found in these the pins in the fuse block under the hood get weak and the relay itself will show a "heat mark" on the fuse block cover if you look at it from the inside, I have had to run new wire to pump , install a outside relay , and trigger from vcm, power to 30 pin from battery, no problems, this is a manufaturing flaw, the circuit to the pump is supposed to be shared with the oil pressure switch circuit.