Truck runs, but can only maintain 20psi

[silverado3500]

The truck is a 2000 f-350 7.3 6 speed. I installed the return regulator mod about 900 miles ago, along with the pre pump and in tank mods. Went to the store tonight, and when I came out, truck started, but felt like it was missing. I checked my fuel pressure gaguge (which I believe is fairly accurate) and am only getting 20 psi. The truck runs, but is not very drivable, and I especially need it this week for work as the power is still out (no thanks to katrina).
I do have a pre pump filter, however there was about a 200 mile gap between when I did the pre pump mods and when I installed the filter. When its light in the morning I will be able to do a more thorough check for leaks, however I could find none tonight, nor was there fuel underneath the truck. Any suggestions are greatly appreciated. Oh, and I forgot, now service engine light either.

Thanks in advance, and I apologize in advance for any delayed responses to questions, however my internet access is greatly limited due to having no power.

 

[smokin_stroker00]

Did you try readjusting the regulator? Mine kept backing off when it was first installed just had to keep putting more pressure on it.Oter than that the high pressure pump may be heading south

 

[silverado3500]

Yes, I tried readjusting the regulator, I carry a basic toolset with me in the truck. The min pressure for the regulator to open is 40 psi. When you say the high pressure pump, you mean the one on the driver's side frame rail right?

 

[silverado3500]

the other thing that I noticed, is that the truck once shut off, was inconsistent about holding pressure. Somedays it would hold 70psi for 7-8 hours, other days the fuel pressure dropped within 15 mins of being shut off. (I noticed this immediately after I did the return regulator)

 

[silverado3500]

I verified, leaks anywhere, not even any residue. Aside from the fuel pump, what (if any) are the other possible culprits? Again, thanks.

 

[silverado3500]

Another update: I started her up this morning, and it seems to be running a bit smoother, however I'm getting no reading on my fuel pressure gauge, so I'm replacing that now, and am going to change the oil, to see if maybe the problems could be unrelated?