Holley In-Tank Fuel Pump Wiring Diagram
A Holley in-tank fuel pump wiring diagram shows how the pump module, relay, ground, and trigger wire connect so the pump runs only when the engine control expects fuel delivery. The request usually comes from owners replacing an external pump or diagnosing a no-start condition where fuel pressure is absent. Because Holley modules may be used across different tank depths and engine configurations, the diagram is a routing and control reference rather than a universal replacement guide. Understanding the circuit helps distinguish a wiring fault from a failed pump, clogged fuel filter, or injector-related problem.
Essential answer
The essential answer is that a Holley in-tank fuel pump wiring diagram maps the high-current supply path, the control side that energizes a relay, and the chassis ground return. Typically the positive feed reaches the pump through a fused relay output, while a thinner signal wire comes from the ECU or ignition trigger. The return path must include a clean ground because resistance there can reduce pump speed, lower fuel pressure, and create a lean fuel trim condition that mimics a failing injector or restricted filter.
A diagram also helps when a pump runs continuously or not at all. No sound at key-on may mean no trigger, a blown fuse, an open ground, or a connector problem rather than a dead motor. A pump that runs without the engine running points to a stuck relay or shorted control circuit. Before replacing the module, a basic leak check at the tank wiring bulkhead and a visual inspection of the harness make sense, but a fault code should only be treated as a clue requiring vehicle-specific confirmation.
