Fuel pump amperage waveforms…. Can they tell us anything that a simple DMM (digital multi-meter) can’t? Those of you that have experimented with them will say a hearty YES! Others, possibly due to exaggerated claims, may be skeptical.
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Here is a fuel pump DC amp waveform of a TBI Chevrolet truck that was towed in. The engine would crank over but not start. Normal DC amperage for this pump would be 3 to 4 amps. |
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Now lets look at the AC amperage waveform of the same fuel pump. Not used to looking at it that way? I own a Fluke 96 DSO and amp probe, but I prefer to use my Fluke 865 GMM (graphing multi-meter) instead due to its ease of use, ability to graph amp waves without a probe, and its easy on batteries. What do we now know about the fuel system? Could we have used a DMM? |
Now lets move on to a few other vehicles….
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This is a fuel pump DC amp waveform from a 97 Chevrolet truck that was towed in. When I first powered up the pump through my GMM, there was no draw. The sudden increase in amperage that you see is when I hit the fuel tank a couple of times with a hammer. What do we now know about the
fuel system? About the sender to pump connections? Could we have used a DMM? |
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This fuel pump waveform came from another Chevrolet TBI truck tow in. DC amperage was a little over 3.5a. I used my amp probe on this one (notice mVAC) What do we now know about the
fuel system? Could we have used a DMM? |
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