1. Verify the Fuel Pump Relay Operation:
* Even with continuity, the relay might be faulty. Try swapping the fuel pump relay with another relay of the same amperage rating (check your owner's manual or a relay chart). A common swap is with the horn relay (if it's the same amperage), but *only* if you can safely test the horn first to ensure it works. If the fuel pump works with the swapped relay, replace the original fuel pump relay.
2. Check the Power Source to the Relay:
* Power feeds the relay's coil. With the ignition ON, use a test light or multimeter to check for power at the power input terminal of the fuel pump relay. If no power is present, trace the power wire back towards the fuse box or ignition switch. You'll need a wiring diagram to help with tracing (a Haynes or Chilton repair manual can be a great help here). A broken wire is a possibility.
3. Check the Ground:
* A good ground is essential. Make sure the fuel pump relay has a good ground connection. Clean the ground points and check for corrosion. Also, check the ground connection at the fuel pump itself.
4. Check the Inertia Switch:
* Many vehicles (especially older ones) have an inertia switch to cut power to the fuel pump in a collision. It's usually located under the dash or in the engine compartment. Check if the inertia switch is tripped. There's typically a button that you can press to reset it.
5. The Ignition Switch:
* The ignition switch itself could be faulty and not providing power to the fuel pump circuit when the key is in the "on" position. This is less likely given your initial checks, but possible.
6. The PCM (Powertrain Control Module):
* While less likely, it's possible the PCM is faulty and not sending the signal to activate the fuel pump relay. This is more difficult to diagnose and usually requires professional tools or an advanced understanding of the vehicle's computer system.
7. Wiring Diagram:
* Get a wiring diagram! Without a wiring diagram specific to your 1993 Chevy G20 van with a 5.7L engine, pinpointing the problem will be extremely difficult. The diagram will show you the exact path of the fuel pump's wiring and where to check for voltage, continuity, and grounds.
Important Safety Precautions:
* Always disconnect the negative battery terminal before working on any electrical system.
* Be aware of fuel system pressure. If you suspect a fuel system problem, it's advisable to relieve any pressure before working on the fuel pump or lines.
If you've thoroughly checked all of the above and still have no power to the fuel pump, you may need to consult a qualified mechanic. A wiring diagram is your best friend in this situation.
