Pump Current Testing

摘要

For years,techs have looked at a fuel pump's electrical health by monitoring the current passing through the system.Current is affected by resistance,but not just the static resistance you measure with an ohmmeter.As the magnetic field builds in the pump's armature,a Counter Electromotive Force is created that impacts the current trace you see on a scope. Additionally,the force required for the pump to turn against the fuel mass will draw even more current to keep the pump moving. Let's say you have little to no fuel pressure.Is it the pump? Connect your low amp clamp to a power supply point that includes the pump motor circuit as well as the relay control circuit.Now try and start the car.If you read "0" amp,then nothing is turning on,check the relay control circuit for problems first.If you read anywhere from 0.3 to 0.8 amp,then the relay control circuit is operating,but the pump side of the circuit is not flowing current.This could mean an opening in the circuit,maybe the relay itself.If you read anywhere from 3.0 to 6.5 amps,the pump is working.There is some mechanical fault preventing fuel from reaching the rail,or bleeding it off before it's getting to your gauge.