So the factory fpr is better than an aftermarket one

 

well, one with a return line and vacuum adjustment is better than an in-line restrictor style regulator. you can also get an in-line with return, but the pressure will always be the same. i'm just getting at the fact that if the factory one is good, might as well use it.

 

You'll never be able to get it to work right with a fixed (non-factory) pressure regulator. The FPR is connected to the intake vacuum for a reason; the pressure ACROSS the injectors has to be constant, so the fuel pressure changes as the intake vacuum changes (which changes with throttle position.)

Put another way, where would set the "inline" regulator to? If you set it to 38psi, you'll lean out at high throttle (low intake vacuum). If you set it at 44psi, you'll flood it at low throttle (high vacuum).

If you have a fuel injection system of any type, the fuel pressure to the injectors has to vary with the intake vacuum. I don't know of any type of pressure regulator that would work without a return line (there might be one, but I've never heard of it). So you need a hooked-up return line, and you need a connected vacuum line.

 

pick up a jegs or summit catalog and you will see all different types of regulators.... maybe even one made specifically for this engine. if you set one at constant 44psi, it would run a little rich at idle, but should adjust in the ltft table by average 02 sensor readings. these engines run a bit lean anyways, imho. but, it will put more strain on the injectors.

 

When I run the truck without the return line connected nothing comes out and there is no vacuum I don't think it works so I put the other aftermarket regulator on the supply line and run a vacuum line off the manifold for the vacuum port

 

Would this inline fuel pressure regulator work?

 

did you happen to put a fuel pressure guage on it? if the pump is not pressured up enough, it won't flow through the return. you could put a vacuum on it and see if it starts dumping fuel. normally, when the regulator goes bad, the spring gets weak, or the seat starts leaking, or the diaphragm ruptures, so it's likely that it is still good. do you have an actual link to the regulator?

 

The regulator is bad so I will be putting an inline regulator on the supply line to slow the pressure going into the injectors.