Fuel Injection Injection Pump Relay (PartTerminologyID 3376): Where Injection Pump Power Supply, ECM Shutoff Circuit, and Diesel Application Architecture Determine Correct Diagnosis and Fitment
Written by Arthur Simitian | PartsAdvisory
PartTerminologyID 3376, Fuel Injection Injection Pump Relay, is the relay that controls switched ignition power to the fuel injection pump on diesel and some early gasoline direct injection applications where the injection pump requires a dedicated relay-controlled power supply separate from the main fuel system relay circuit. The relay supplies operating voltage to the injection pump motor or solenoid-driven pump mechanism, and on ECM-managed diesel applications it also interacts with the ECM's fuel shutoff output, which de-energizes the relay to stop the injection pump and halt fuel delivery when a shutdown condition is commanded. The three attributes that determine correct fitment are the injection pump type the relay supplies; how the relay interacts with the ECM shutoff circuit on electronically controlled applications; and the differentiation from the Fuel Pump Relay (PartTerminologyID 3380), which controls the in-tank transfer pump on most gasoline applications and is a separate circuit from the injection pump relay on diesel systems that use both components.
What the Fuel Injection Injection Pump Relay Does
Injection pump power supply and ECM shutoff interaction
On mechanical diesel injection pump applications, the injection pump relay supplies ignition-switched power to the pump's electric fuel shutoff solenoid, which holds the pump's fuel delivery mechanism in the open position while energized. When the relay opens, the shutoff solenoid de-energizes and a spring-loaded valve closes inside the pump, stopping fuel delivery and shutting the engine down. This means a relay that fails open during engine operation will immediately shut the engine off by removing power from the shutoff solenoid, and a relay that fails closed after a shutdown command will prevent the engine from stopping because the solenoid remains energized and the pump continues to deliver fuel. On electronically controlled common rail diesel applications, the relay supplies power to the high pressure injection pump motor and the ECM commands relay de-energization through a discrete output to halt injection pump operation during shutdown or fault conditions.
Differentiation from Fuel Pump Relay (PartTerminologyID 3380)
The Fuel Pump Relay (3380) controls the in-tank electric fuel transfer pump that moves fuel from the tank to the injection system at low pressure on most gasoline and modern diesel applications. The Fuel Injection Injection Pump Relay (3376) controls the high pressure injection pump that pressurizes fuel for delivery to the injectors. On diesel systems that use both an in-tank transfer pump and a mechanically driven or motor-driven high pressure injection pump, both relays are present and both must be functioning for the fuel system to operate. A buyer who orders PartTerminologyID 3380 when their application requires 3376 will receive a relay for the transfer pump circuit rather than the injection pump circuit, and the two relays serve different positions in the fuel system architecture with different current ratings and activation logic.
Top Return Scenario
Scenario 1: "Diesel engine cranks but will not start, no injection pump activity"
The injection pump relay contact has failed open. The injection pump receives no power during cranking and produces no fuel pressure at the injector rail. Testing voltage at the injection pump power supply terminal during cranking confirms absent supply voltage. Confirming relay coil activation voltage is present during cranking before testing pump supply voltage identifies the relay contact as the fault rather than the ECM shutoff output or the pump itself.
Prevention language: "Test for relay coil activation voltage during cranking first, then test for injection pump supply voltage at the pump connector. Coil voltage present but no pump supply voltage confirms a relay contact failure. No coil voltage during cranking indicates an ECM output fault or ignition circuit fault upstream of the relay."
Listing Requirements
PartTerminologyID: 3376
injection pump type: mechanical shutoff solenoid or high pressure pump motor (mandatory)
ECM shutoff circuit interaction on electronically controlled applications (mandatory)
differentiation from Fuel Pump Relay (PartTerminologyID 3380) (mandatory)
diesel vs. gasoline application confirmation (mandatory)
OEM part number cross-reference (mandatory)
FAQ (Buyer Language)
My diesel engine shuts off while driving. Could this relay be the cause?
Yes. A relay with intermittent contact failure that opens momentarily during engine operation removes power from the injection pump shutoff solenoid on mechanical diesel applications, immediately halting fuel delivery and stalling the engine. The engine will restart once the relay contact closes again on re-energization. Intermittent stalling that restarts easily on a diesel application is sufficient justification to test the injection pump relay contact resistance and replace the relay before a complete contact failure occurs.
What Sellers Get Wrong About PartTerminologyID 3376
The most common listing error is conflating this relay with the Fuel Pump Relay (3380) under a generic fuel relay description. Diesel applications that use both an in-tank transfer pump relay and an injection pump relay have two distinct relay positions serving different pump circuits at different pressure levels with different current ratings. A listing that does not identify the injection pump circuit specifically will generate orders from buyers whose application requires the transfer pump relay, and vice versa. Every listing under PartTerminologyID 3376 must state the injection pump supply function, identify the diesel or direct injection application architecture, and differentiate from the transfer pump relay (3380) to prevent application mismatch orders.
Cross-Sell Logic
Fuel Pump Relay (PartTerminologyID 3380): the transfer pump relay and injection pump relay are both required on diesel systems that use an electric in-tank transfer pump; both should be tested on a diesel no-start complaint
Diesel Glow Plug Relay (PartTerminologyID 3392): glow plug relay failure produces a hard cold start symptom on diesel applications; should be tested alongside the injection pump relay on cold diesel no-start complaints
High Pressure Fuel Pump: if injection pump relay supply voltage is confirmed at the pump connector but no fuel pressure builds at the rail, the high pressure pump mechanical assembly has failed
Final Take for PartTerminologyID 3376
Fuel Injection Injection Pump Relay (PartTerminologyID 3376) is the diesel injection pump control relay where pump type identification, ECM shutoff circuit disclosure, and differentiation from the Fuel Pump Relay (3380) are the three listing attributes that prevent the most common application mismatch and misdiagnosis returns. The differentiation from the transfer pump relay is the highest-priority listing element because the two relays are present in the same relay center on many diesel applications and are ordered interchangeably by buyers who do not understand the two-circuit fuel system architecture. Sellers who identify the injection pump supply function, state the ECM shutoff interaction, and explain the two-relay diesel fuel system architecture give buyers the information needed to order the correct relay position on the first attempt.