SPOOL Low Pressure Fuel Pump PWM Activation Harness – BMW

SPOOL Low Pressure Fuel Pump PWM Activation Harness – BMW

The Spool PWM harness controls an auxiliary in-tank pump with pulse-width modulation instead of running a brushed pump continuously at the full 13.5–14 volts through a conventional relay. PWM control reduces unnecessary heat, brush and bearing wear, and heat added to the fuel tank.

This is particularly relevant with a Walbro 525, which Spool states can draw roughly 20–25 amps under heavy load and even more at high fuel pressure.

Contents and control

• Spool harness with braided protective sleeve
• 10/12 AWG Tefzel wire
• Genuine Hella solid-state relay
• Deutsch connector for plug-and-play or flying-lead ReFlex wiring
• Ground-trigger activation

The harness uses a ground trigger only. On a plug-and-play ReFlex installation, disconnect the positive activation connection as instructed by the manufacturer. Installation should be handled by someone familiar with automotive electrical systems.