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<BR>hi, I think this might help. First, I'm a GM drivability tech. guage
<BR>fluctuation is normal, and will very depending on the vehcile its connected
<BR>for a few reasons and here are just a couple. #1. pulsing injectors, fuel
<BR>pumps have a smooth output even when they are going bad! #2 air in the
<BR>pressure guage line will dampen the fuel pressure pulses, If the guage has an
<BR>air bleed and this is utalized which I don't for this very pupose, the guage
<BR>will fluctuate alot, so some techs going from one car to another and one car
<BR>multiple times without purging all the fuel out of the guage line will notice
<BR>this fluctuation. #3 some vehicle are equipped with a inline dampener to
<BR>help eliminate this pulsing, and this can also alter reading form one vehicle
<BR>to another. they do this because of pump whine, caused by the pulsing of the
<BR>injectors. if your are concerd with a lack of fuel volume and pressure do
<BR>this. tape your guage to the windsheild and go drive the vehicle. smash the
<BR>gas and hold it.
<BR>pressure should increase and become steady, i.e minor fluctations not
<BR>important, but it should not rise to say 48 psi and then fall with gas peddle
<BR> smashed to the floorboard. tipically falling indicates a bad pump, but don't
<BR>over look the regulator than can be trickey like that.
<BR>hope that helps!!
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<BR>-Brian
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