Of course even if the FPR is stuck wide open 30 - 32 is way too low.
Plan on probably buying a pump. And for what it costs you could put a new FPR on it too.
Just my .02 worth.

 

Alright guys. I know its been a while since I started this, but I had to work a shutdown and work has been crazy. I got the fuel pump replaced and now the problem actually seems worse. I tried to drive it and every time I tried to press the gas, it would sputter and finally die. It will not run above idle. I replaced the filter thinking that I may have gotten something in the fuel line while I had it apart, but that didn't make a difference. With the key on and engine off, I jumped the pump at the data link connector and was only able to get 29psi. I pulled the return line off the regulator, jumped the pump and didn't see any gas coming out. Any suggestions? Maybe I got a bad pump?

 

When you turn the key to on and get 29 psi, then turn it off, how long will it hold 29 psi ?
Should be able to hold that for at least a few minutes (mine is still at 42 after 15 minutes).
If it holds pressure then the pump would be a suspect.
If it doesn't, it means the pressure is leaking out of the system. That could be through the injectors (dirty?) through the FPR (out the vacuum line or out the return line) or leaking back in to the tank (not the first suspect in this case). There's nowhere else for it to go, except onto the ground which you would have noticed of course.

 

I have been going through this same exact thing. If you have not replaced the check valve at the pressure side of each pump, I would think (because this is where I am at) that this would be the next thing to do. I have found that fuel will leak past the check valve therefore going back into any and possibly all tanks.

I have been told that it would be ok to leave the check valve in place because the fuel will still flow to the rail. Just splice in a new valve close to the tank. I am in this process. Dorman Part # 800-196 for rear tank. It is a 3/8" line. The front I found at seems to be smaller 5/16" it would be Dorman part # 800-195.

I have done or replaced everything fuel related (in process of front check valve), except inertia switch (which doesnt make sense) and pulling fuel rail to see which if not all injectors are leaking.

I have a 91' f150 xlt lariat 5.0L dual tanks. not sure about tranny.

 

It'll hold pressure for a few minutes. Only has one tank.

 

Guess I missed that in OP. Was hoping that would help. I like ford but they do have their share of Problems I guess as do all

 

So your pressure isn't immediately leaking away. Which should rule out leaky injectors or FPR as the problem. Also you said nothing is going past the FPR into the return line.
So the problem would seem to be on the delivery side. You only have 1 tank so it's not leaking pressure into the other tank. You put a new filter on it.
I would have to guess it's a clogged pressure line or that pump you just put in is no good.
If the line is disconnected at the fuel rail and at the pump, you should be able to blow through the line even with the filter in place. If you can't try the 2 parts of the line without the filter. That's if you want to eliminate all other possibilities before you tell the supplier to give you a new pump.
It sounds like a bad pump problem, the only thing that's making me wonder is that it seems like the old pump and the new one both came up at 29 psi, if I remember that right. Could be coincidence but it's suspicious .....
These are just all best guesses you understand. All anyone can do from thousands of miles away.

 

What brand of pump did you put on/where did you get it? New pumps aren't always perfect (especially from autozone) but I would agree with chris that two pumps putting out the same low pressure points to a problem with the lines (factoring in your tests and other replaced parts).

 

The new pump is a Delphi. I guess I'm going to drop the tank again. I'll try blowing through the lines when I get everything disconnected. Even if there was an obstruction in the line though, shouldn't I be able to get more than 29psi running the pump with the engine off? I would think that would be like running it deadheaded.

 

You would think. But what's happening with your truck just doesn't fall into the normal. With all the other info you've got posted, a blocked line or weak pump are the only things that make sense at this point. At least to me - I could be missing something here but that's my best guess. Into a process of elimination now.