Fuel-Pump Relay Stress Loaded Test
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Due to the importance of using the stress loaded test light or any form of loading the circuit to stress the faulty issue, we've created the following explanation on the subject. In this example, we've taken a faulty fuel pump relay, and stress the circuit to see how this affects it.
We'll start by saying that this is a simple fuel pump relay actuated by the ECM, much like any other similar unit. In our case, the relay contacts have become pitted over time and have developed severe carbonization and therefore, resistance. As in many a similar cases, the excess resistance makes the fuel pump run slower, due to lack of needed electrical current. The end result is engine performance problems and lack of power.
Before exposing the procedure we have to know a few caveats.
One, at this time, the diagnostic technician has no idea where the faulty issue is at. In other words, he doesn't know that the pump relay contacts are pitted, carbonized and resistive.
Two, since he doesn't know where the issue is, the use of a voltmeter is irrelevant. All the technician can do with a voltmeter is probe between battery positive and the fuel pump, and just know there's a voltage drop somewhere, if at all detectable.
And three, this issue is not a dead open circuit. It is a semi open or high resistance issue, but, not high enough to cause a severe voltage drop anywhere, especially at the current rating that this fuel pump operates. Most newer fuel pumps operate at about ...
Get the whole story right now in this video.... Enjoy....
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