TPI fuel pressure

[Bja1078 at aol.com]

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

-Brian 

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