Missing something? Fuel psi 10psi low

[gilly327]

98 k1500. Got lean codes for both banks. Checked fuel pressure. Runs at 49 psi. Assumed was pump so replaced it with a new Delphi unit. No change. Figured I’d replace fuel filter. Didn’t know the age of it and ends were rusty. Found out it was installed backwards. New filter. No change. Newer style spider setup. Swapped the fuel regulator with one I had. Gained couple psi but it was from an old spider set up and I know those need more psi. Noticed bleeds down quickly and nothing leaking from spider so figure pump was defective and warranted it. Also sputtered and stalled with this pump and never did that before. new Delphi unit was blue and under new parent company Bosch so I figured that must’ve been it since the “defective unit “ was older style box. Same issue. Bled down fast so put old regulator back in and that stopped. Still bleeds down but instead of bleeding right down it’s slow like a couple psi in a couple minutes. Installed new pump and same issue. 13 volts at connector when running and Has good ground at connector. I swapped engines last fall. The spider setup and swapped and tried was from my old engine. Didn’t have any fuel issues with it except the gas gauge being inaccurate so that’s why I figured it try swapping it to see if any better.

 

[RichLo]

Have you checked the vacuum lines going to the FPR?

 

[gilly327]

The FPR doesn’t have vac line going to it. Its under the plenum

 

[L31MaxExpress]

When is it running at 49 psi? With the stock spider, fuel pressure should be 66 psi. With the the upgrade spider, should be 58 psi. Both figures with the Key On, Engine Off and the pump running.

 

[gilly327]

When it’s running it’s at 49-51. Aftermarket spider. Factory spider would run around a couple psi higher Key on Eng off with aftermarket spider would read 60 psi and would click and go to 55. And slowly bleed to about 50 and sit there. spider again with factory would be a couple psi higher. The picture is it currently idling with aftermarket spider