i installed my gauge and took it for a drive at idle im at 15psi driving down the road im at 20-25psi when i let off the throttle and cruise it hits 29psi

 

It's too low, suggest a new overflow valve.
22-26 is normal at idle
18-35 at high throttle

 

i just installed a new OF valve and filter. is it possible to have the isolater upside down would that cause it to read wrong or does it matter

 

No difference with the isolator.
Do you have a needle valve that's almost closed or a gauge snubber at the head of the line? If not the pressure will never read right with a 12 valve.
Electric or mechanical gauge?
Where is connected to?
How many psi is the gauge? If it's 100psi you won't get good readings down at the bottom of the scale.

 

My readings with a weak lift pump were slightly lower than yours. Pinching the fuel return line together will build up pressure if the overflow valve is bad and the lift pump is working.
Not being be to reach stock pressure+ with a pinched return line indicates a supply problem such as a lift pump, filters, etc.

 

30 psi mechanical gauge no snubber or needle valve what do they do? i have it connected to the line coming out of the filter to the pump. peirs told me that was all i needed, it came with an isolator which has a rubber diaphrm in it you fill one side with anti freeze and the other with fuel i think my problem is i didn't fill one side comletely with fuel. you guys know alot more than me so just give me some info

 

A snubber or needle valve stops pulsations.
Try the pinch the return line trick dalton recommended to rule out the lift pump. Some OF valves have been known to be bad from the get go. If that's not the problem the only other thing it could be is a gauge that isn't reading right.

 

where do i get a snubber or needle valve it does pulsate back and forth alot. do i need to fill the isolsator full of fuel or does the line just need a little fuel in it to make it work

 

I get my needle valves here http://www.grainger.com/Grainger/pro...835462&ccitem=

but any bigger hardware store will have them, they're used for icemakers and swamp coolers.

It doesn't matter if there is air in the lines, it will eventually fill with fuel.

 

Your 30 psi gauge is on the short side. TST gave the following pressure norms:
Idle.. 18-24 psi, 2000 RPM (no load).. 28-36 psi. A low normal reading will max out your gauge.

 

i tried to find a needle valve yesterday all the hardware stores only had them for 1/4in and bigger tubing. it does max my gauge out as soon as i let off the throttle goes from 25 to 30. i haven't tried pinching the line i haven't had anyone around to help me with it