1992 E250 5.8 Fuel Pressure reading?
 

I have a 1992 E250 with a 5.8 and apparent fuel issues. I tested the fuel pressure and found 44 PSI without vacuum and 35 PSI with vacuum at a normal idle. Everything I have found with that kind of detail tells me I should be seeing about 39 PSI without vacuum and about 30 PSI with vacuum.

What should it be for my van? This sounds like too much variation. Since most regulators I have found cover a wide range of trucks, I suspect if I replace the fuel pressure regulator I will get 39 PSI. Is this enough of a change to cause a problem?

Sounds like your Fuel Pressure Regulator (FPR) is OK.
You should get around 45 PSI reading with the vacuum line off and depending on your vacuum you should get 32-34 PSI at idle.

I do not know where you seen the 39 & 30 but who ever said it was wrong.
You vacuum may be a little low or your engine was idling a little high.

Most 5.8L engines will did at between 28-30 PSI fuel pressure.

Every one that I have worked on and others I have worked with the above is true and not what the book says below.

ENGINE RUNNING 30 - 45 PSI
KEY ON, ENGINE OFF 35 - 45 PSI

I do not know how they would come with those readings.

my pressure stays aT 20 psi until u crank it over then steadily climbs to about 50 . stop turnin it over then it comis back down to 20 . i just replaced fuel pump with one that i knew worked abd now it does what i said above . what else can i check