The reason I wanted to try this mod was due to the frequent pump replacement problems that cookie88, Scott - FTE Moderator of the 99-03 PSD forum, has been experiencing with his PSD. Since I had already installed a 2 micron pre-pump filer while doing my in-tank modification, I felt that the added restriction of the filter might place an additional load on the factory fuel pump and I didn't want to be replacing a $200 pump every 18 months!

Following Scotts lead, I ordered a $60 Carter P4070 electric fuel pump. It is rated 5 - 6 psi, 72GPH and I have calculated that this small pump would be adequate to use for a simple lift pump to supply the high pressure factory fuel pump.

I did have some concerns on feeding pressure to the Racor filter since the inlet was marked 'vacuum only' but after checking Racor's web site I felt I would be safe. Their smallest filters are rated 7 psi with the larger ones going up to 30 psi.

After reading the installation instructions that came with the pump, I picked up a small in-line fuel filter (40 microns) just in case I pick up some rocks during a refueling stop.

Impressions

Even with the additional vibration mounts, you can hear this pump running during the WTS cycles. Once the engine is started, it is not noticeable at all.

Engine starting was only slightly quicker, 2 revolutions of the engine vs. the 3 or 4 that I was used to expecting.

I took a test drive and tried my TS Performance tunes through the 50, 75 and 100 hp settings. The 50 and 75 hp felt about the same as previous, maybe a little more but not real noticeable. I never used the 100 hp setting in the past because the SOTP feeling was that it gave me less go than what I felt in the 75 hp setting. Well, NOT NOW! The WOW factor kicked in with the 100 hp tune and there was a very noticeable difference over the 75 hp tune. That's probably when I decided that this mod was going to stay.

I did not have a pressure gauge to measure fuel pressure going to the rails at the time of this mod but my guess is that the addition of this 'helper' pump either increases the delivered pressure by giving the main pump all the fuel it can handle or simply allows it to deliver a larger volume of fuel to the engine.

Since I have never removed the factory pump, I thought this would be a good time to check the inlet of the pump for any debris that may have passed through the mixing valve screens prior to doing the in-tank modifications. To my surprise, I was not able to find any large particles in the pump after shaking, tapping and draining as much fuel out of the pump as I could. So, remount the pump and on to the mod.

Scott's idea was to wire the new pump in parallel with the factory pump. This way when the high pressure pump was energized, so was the helper pump. The first step was to pull the #40 fuse (under dash on my 02) for the fuel pump. This was a yellow - 20 amp mini-fuse. I then passed a 14 gauge wire through the weather boot on the positive terminal of the factory fuel pump, crimped on a new terminal ring and placed it on top of the original terminal. The new pump will be chassis grounded for the negative terminal.

After fashioning a bracket from 3" x 1/8" strap metal, the pump is mounted. The pump bracket that is supplied comes with vibration absorbing grommets which will be nice since this pump is on the noisy side. In addition to Carter's vibration mounts, I plan on using rubber mounts on my DIY bracket also. The ground wire that came with the pump was too short to reach my chassis ground point so I will need to make an additional ground line that will connect to the bracket bolt on the pump and runs directly to the frame.

The rubber washers that I used on the 5/16" mounting bolts were left over from some other project and were exactly what was needed to give this pump some additional noise dampening.

With the pump mounted in place close to the fuel tank, I inserted the small in-line filter in front of the new pump just for a little additional protection. The in-line filter was an after-thought and I would like to find a 100 micron screen filter to replace it with. Just for fun, I used a see through, yellow diesel rated hose between the new pump and the Racor 2 micron filter. Having no other way to watch for air in the fuel coming from the tank, I thought this would be interesting but will eventually be replaced with 30R9 fuel hose. After the initial purge of the new pump, there was no sign of bubbles flowing to the 2 micron filter.

The 14 gauge hot wire between the pumps was protected with 1/4" plastic wire loom material. Dielectric silicone grease was applied to the pump boots and re-installed on the posts. The #40 fuse was replaced and I cycled the pumps through to purge the air from the delivery system. Everything was wire-tied in place and a final inspection for leakage was performed.