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Fuel Pressure Regulator only reading 45psi but rail pressure is 58?

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Old 10-21-2016, 11:26 AM
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Default Fuel Pressure Regulator only reading 45psi but rail pressure is 58?

Just installed an external fuel pressure regulator into my return line. I have 03 silverado which comes with return style and has the stock FPR in the fuel rail. I got a bypass plug so i removed the stock FPR and replaced it with the plug. then i plumbed in the FPR into the return line and put stuck a pressure gauge directly on the FPR . At the same time I have a gauge connected to the rail fitting to monitor the rail pressure. Since I bypassed the stock FPR i would think that the rail pressure would be the same as what is displayed on the regulator? maybe the new gauge I just got that is on the regulator is bad? any ideas? the gauge that i have connected to my rail picked up about 55 with the stock regulator a few months ago so i know that was working at that time ...

this is with the truck running , you can see its about 45psi ( i did not get gauge that was on the rail but it was showing 58 )






what do you think?
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Old 10-21-2016, 12:17 PM
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unplugged the vacuum line and the pressure on the regulator went up. adjusted it to 58psi on the regulator and plugged the vacuum back in . rail pressure at idle is around 58~60psi now so i think i answered my own question and should be good to go!

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Old 10-21-2016, 11:25 PM
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another thing to keep in mind too is as those analog gauges heat soak, they read lower psi.



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