That regulator really isn't designed to do that but your return line is way to small. If you go up to a -6 you should be able to get it down to 7psi

 

yes, your return line is too small. I had the same problem. I chose to add a 2nd regulator (dead head regulator) off the discharge port of the first because it was much easier than running a new return line on my finished car. I run 18 PSI off the bypass regulator and 6 PSI off the 2nd. Works perfectly. :beer:

 

What he said.

same here, +1

 

Fixes

All my lines and fittings are -6. At the pump it goes down to 3/16" on the return.
Any other options to my problem. I would really like to stay in-tank.
Also I ended up talking to the head tech guy at Holley and he told me to pull off the return line and route into gas can, no problem getting the 5.5 psi I needed when I did as he suggested.

 

All my lines and fittings are -6. At the pump it goes down to 3/16" on the return.
Any other options to my problem. I would really like to stay in-tank.
Also I ended up talking to the head tech guy at Holley and he told me to pull off the return line and route into gas can, no problem getting the 5.5 psi I needed when I did as he suggested.

That right there says your return line is too small.
Maybe the tech guys aren't full of shit?????

 

By the way it was my first start after 2+ Years of the engine sitting in my garage it sounded great. Video to come once I fix fuel pressure issue.

 

bypass the regulator and measure the pressure just running it straight back to the tank. My bet is you have 10.5 psi pressure drop JUST in the return line. In other words, you'll never be able to regulate below that unless you go to a larger return line or add a 2nd regulator.

I measured something like 15-16 PSI pressure drop in my return line with my 255 lph high pressure pump (in tank), so I set my main bypass regulator to 18 PSI (just above the pressure drop of the return line), then dial down it's regulated outlet to a rock solid 6 PSI using the 2nd regulator.

 

Gordon is right, your return line is too small. Your supply line is also to small for an in-tank pump that supplies 225 lph as well. You should have a minimum of 3/8" supply for that size pump or -8 and a 5/16" return or -6 for return. That pumps days are numbered with the back pressure you are putting on it. Even with a secondary FPR you're asking too much of that pump. You'd be better off changing out the pump for an in-line pump that is a low pressure pump.

 

If your front cover has the opening and your cam has an eccentric on it, you could go mechanical and never worry again.

 

X2 on Craig's suggestion; if possible, install a mechanical pump on the engine and either remove or bypass the high pressure pump in the tank. To run the HP pump throttled down to ~6 psi is like sitting at a stoplight with an auto trans and holding down the gas with one foot and the brake with the other. Something will fail sooner or later.