Where can I find specs for in-tank fuel pump pressure?

 

It's not easy to find in print, but the spec is:
3.8-5.0 Bar, [55-72 PSI] referenced to inlet manifold pressure.

It will hang right at 3.8 bar unless driving under a load.
Referenced to inlet pressure means taking into account inlet pressure, meaning manifold vacuum. In other words, manifold vacuum is also "sucking" the fuel from the injector.

To translate, if reading the rail pressure with a scantool, you'll see about 55 PSI. If reading with a mechanical gauge in the supply line, you'll see about 8-9 PSI less. That's the pull of the manifold vacuum.

And you thought it was simple!

Cheers,

 

And it will change depending on RPM and load. I have watched my STR fuel pressure with a mechanical gauge for some time. I see a range around 45 psi to 70 psi give or take several psi. So don't expect a steady ready of 55 psi.
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I worded that sort of poorly, didn't I?
Edited to clarify a bit.

Gotta keep me honest, guys........

 

Hi Steve;
No you are correct, I just had to jump in!

I had a run with a bad fuel pressure sensor on my STR so I played around a good bit with my fuel pressure tester trying to troubleshoot it. At that time I had spikes as high as 110 psi!!
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