I installed the new fuel pump and I thought the numbers were going to be higher. I have 15 (old lp was 12.5) psi at idle, 13.5 (old 9.5) cruising on the highway pulling a 4k trailer and 10.5 (old 5.5) at WOT towing the trailer. It was -4 F, does the colder temps make a difference? Man winter fuel sucks for fuel economy...

 

Idle sounds fine. I can't pull mine down below 15 PSI ever. Have you changed your fuel filter lately?

 

I changed the filter last November, only about about 1500 miles on it since then. I run DSG winter fuel additive also. I do not have the big line kit from the filter to IP installed yet, would this cause the lower numbers? I would think the smaller the hose, the higher the pressure number?

 

Make sure if you have an isolator, that you rebleed it out after the install.....HPFP pressure should be up around 16-18 PSI.....

Only other thing that can cause pressure drops is restriction on the suction line. Make sure you have a NAPA 3270 STRAINER in the line before the tank and pump and the arrow is pointed in the correct direction.

 

Do you mean an isolator between the IP and the gauge? If yes, then I HAD one, but it was "difficult/impossible" to bleed (the interior of my truck still smells of antifreeze and diesel, wifey not like that...) and I could never get "right" numbers. I turfed it and put on a needle type valve, its barely cracked and the gauge displays things great, no pulsations, moves nice and smooth, etc. Would the "big line kit" give me an increase in pressure, I was thinking it would allow for more volume...

Yes, I have the proper strainer, in the right direction, I bought the kit from Vulcan performance and it had everything. Including a VERY cool sticker.... I love stickers... just not on my truck or bike...

 

It shouldn't increase your pressure at idle, but I think you will see a higher pressure @ WOT. I used to get about the same readings you are now, then I added the 1/2" line from the filter to IP and now the lowest my pressure ever gets is ~13.5 psi.

 

Mine gets 15 at idle. Can't pull it below 10. HPFP is regulated for proper pressure.