TooBroke: I've already installed the '85 fuel pump, I'll get in contact with you about the regulator spring. - Thanks
Back in 2005 I did some extensive testing of my '82 to find out why it seemed to lose power so bad right when it hit 3400-3500 rpm. I started by testing the free flow of my stock pump by powering it with my 4-amp trickle charger and pumping into a big 7-gallon plastic bucket for one minute. Then I multiplied the volume by 60 to determine how much it pumped per hour. About 43-44 gallons per hour which is about the same as a mechanical pump would deliver.
Then I pumped the fuel thru the pressure regulator that was set at 11 psi and the flow dropped to about 22-23 gallons per minute; far short of the 33-34 gallons per minute a 350" engine running at 80% efficiency would require at 6000 rpm. Then I pinched off the fuel return hose to see how much pressure the pump would make before it maxed out and found it signed off at 12 psi when it started bypassing internally.
Not knowing an '85 fuel pump would directly interchange with the '82 thru '84 pumps I installed a rear-frame mounted Hypertech gearotor pump that was rated for 43 gph @ 90 psi at 7-1/2 amps and stretched my pressure regulator spring about 3/4" longer; giving me exactly 14 psi.
Road testing it with a 0-15 psi pressure gauge inside my cabin I found it would maintain a full 14 psi all the way to it's redline and with the increased volume and pressure the Hypertech pump delivered I was astonished over how much additional power it made from about 2800 to 4400 rpm where it suddenly signed off because of the restrictive 425 cfm CrossFire intake manifold. I played around with higher pressure regulator settings and found pressures 2-3 psi above 14 psi produced a lot of black smoke and a loss of power so I settled on the 14 psi as that felt ideal.
Then after boring my throttle bodies to 2.0" and installing my Renegade two years ago my engine will now make terrific power all the way to 6000 rpm but the most noticeable power increase comes between 2800 and 4500 rpm where it's needed the most and I attribute most of that to the fuel system modifications.
The first thing you'll need to do is solder a brass T into your fuel line so you can easily check your pressure with a common 0-15 psi pressure gauge then modify your fuel pressure regulator for easy adjustment (or buy an inexpensive adjustment tool from DCS) and stretch the spring an additional 3/4" to get the desired 14 psi. As you have already installed the '85 pump you'll only need to make the pressure regulator modifications to see a dramatic increase in power from idle up to 4400-4500 rpm..................................
Once the fuel pressure has been increased to 14 psi no further adjustment is needed from then on but the brass pressure tap will always come in handy for future troubleshoooting. To maintain the same bend of the fuel line the tap must be soldered in place (with a propane torch) with the fuel line connected so when you're soldering it in be sure to protect all of the surrounding plastic parts with sheet metal so they won't melt.