Fuel pump electrical diagnosis
No fuel pressure. Before ordering a pump, prove whether it is being asked to run and whether it can draw current.
What this lesson covers
CORE TEACHING Relay/module pump control; priming; low/high-speed control; pump ground; mechanical load; current draw. PRACTICAL DEMONSTRATIONS AND TESTS Command pump; check voltage at pump under load; ground drop; clamp current; pressure comparison. ADVANCED / SCAN TOOL LAYER Current-ramp scope can show commutator segments/worn pump motor; PWM pump-module output. KEY DIAGNOSTIC QUESTIONS Is pump commanded? Is voltage reaching it? Is current flowing? Does electrical effort create fuel pressure? MUST-COVER CHECKPOINTS Map simple vs module-controlled architecture; prove heavy power and ground; verify switch/request; command output; measure load current; inspect signal/network where used.
What you will be able to do
No fuel pressure. Before ordering a pump, prove whether it is being asked to run and whether it can draw current.
Where it sits in the programme
- Builds on
- Lesson 31: Blower motor diagnosis
- Feeds into
- Lesson 33: Cooling fan circuits