Attention: TDR Forum Junkies 
Hi all,
So I recently upgraded my ancient FASS lift pump to a Fuel Boss mechanical lift pump from Glacier Diesel Power. It has a bypass valve that allows fuel to return to the tank at a certain psi. I bought a "Tuning Kit" for that valve so that I could set the pressure exactly where I want it. I have been trying to get it just right but I keep ending up with it either a little lower, or a little higher than I want. I need help figuring out if I am looking for the wrong number or what, and where I should set it. I have in my head that anything over 20 is too high but at the same time I don't want it to get too close to 15 either lol. After messing with it for a few hours today I decided to er on the low side. I tried all kinds of combinations of the spacers and 2 different springs the come with the valve and tuning kit and can't find a happy medium. Everything is either too high or too low. I ended up with idle at about 17-17.5. And IIRC that puts it at about 18 at 65mph. Those numbers are the approximate average between my two gauges. I have an autometer mechanical gauge with isolator on the pillar and a Vulcan test gauge from Geno's. The test gauge always reads about 1.5 psi higher than the autometer. Since the pump is mechanical, the pressure generally goes up from idle, but it does dip very slightly at first (about 1-1.5 psi) If i stomp on it or when letting the clutch out without throttle. Basically until the rpms catch up with the fuel demand. I wanted it just a touch higher but I just can't get it there. Next step up puts it at 18 or 19 idle and then it gets over 20 up to about 22-23 at 2400 rpms. That just seems too high to me. What do you guys think? Knowing that it will dip about 1 psi or so, would you go on the high side of 19 idle and 22-23 at 2400rpms, or would you go lower with 17 at idle and around 19 at that rpm? I just get concerned when it goes over 20 psi, especially since I know it rises with rpms and Im not sure how high it will go...I mean, what if it hits 25 or more? But I also don't like it anywhere close to 15 either. Anyway like I said, what would you guys do? I know Im worrying about this too much, but I'm really OCD and I need the opinion of someone with more experience.
Oh by the way, these numbers are all with my Smarty on SW5 so they might go up slightly with it on a lower setting. Its not much though.
Thanks!
Nate
So I recently upgraded my ancient FASS lift pump to a Fuel Boss mechanical lift pump from Glacier Diesel Power. It has a bypass valve that allows fuel to return to the tank at a certain psi. I bought a "Tuning Kit" for that valve so that I could set the pressure exactly where I want it. I have been trying to get it just right but I keep ending up with it either a little lower, or a little higher than I want. I need help figuring out if I am looking for the wrong number or what, and where I should set it. I have in my head that anything over 20 is too high but at the same time I don't want it to get too close to 15 either lol. After messing with it for a few hours today I decided to er on the low side. I tried all kinds of combinations of the spacers and 2 different springs the come with the valve and tuning kit and can't find a happy medium. Everything is either too high or too low. I ended up with idle at about 17-17.5. And IIRC that puts it at about 18 at 65mph. Those numbers are the approximate average between my two gauges. I have an autometer mechanical gauge with isolator on the pillar and a Vulcan test gauge from Geno's. The test gauge always reads about 1.5 psi higher than the autometer. Since the pump is mechanical, the pressure generally goes up from idle, but it does dip very slightly at first (about 1-1.5 psi) If i stomp on it or when letting the clutch out without throttle. Basically until the rpms catch up with the fuel demand. I wanted it just a touch higher but I just can't get it there. Next step up puts it at 18 or 19 idle and then it gets over 20 up to about 22-23 at 2400 rpms. That just seems too high to me. What do you guys think? Knowing that it will dip about 1 psi or so, would you go on the high side of 19 idle and 22-23 at 2400rpms, or would you go lower with 17 at idle and around 19 at that rpm? I just get concerned when it goes over 20 psi, especially since I know it rises with rpms and Im not sure how high it will go...I mean, what if it hits 25 or more? But I also don't like it anywhere close to 15 either. Anyway like I said, what would you guys do? I know Im worrying about this too much, but I'm really OCD and I need the opinion of someone with more experience.
Oh by the way, these numbers are all with my Smarty on SW5 so they might go up slightly with it on a lower setting. Its not much though.
Thanks!
Nate
