What fuel pressure do you run if you have a gauge?

[joecool911]

I'm new to 20 psi. When cold and the intake heater kicks on and off I cycle between 16 and 20 psi. I figure its a condition of lower operating voltage? Volt gauge goes down, lights dim, wipers slower. Is this all normal? I figure the voltage drops to that of near 12 volts because of amp draw and when the heat plate shuts off the voltage goes back to that of the alternator (14.5). Thus slowing the volume from the pump, since its electric too.

[dripley]

The grid heaters pull a lot of power. What you are seeing is normal.

[CUMMINSDIESELPWR]

yup normal

[Ilikeoldfords]

As for my pressure drop, the only thing it could be is in the tank I am thinking. I just replaced all the fuel line and fittings from the top of the tank to tank to the VP. Everything is 3/8's now. I know 1/2 would have been better but most of the fittings were all 3/8's already. The filter I put before the LP should really be big enough because it is the same filter used on most class 8 cummins truck engines. I will have to drop the tank one day and see whats going on in there. I am running a isspro mechanical gauge between the stock filter and VP, using a needle valve.

[joecool911]

I'm very pleased with my fuel system now. 15/20 psi. The Raptor 100 seems to be adequate. Everything is settling in consistent and reliable. Would my old carter pump work with the raptor wiring harness under the truck as a back up? Problem is that it was only doing 5/10. Not sure that's even enough for a backup.

[CUMMINSDIESELPWR]

I'm very pleased with my fuel system now. 15/20 psi. The Raptor 100 seems to be adequate. Everything is settling in consistent and reliable. Would my old carter pump work with the raptor wiring harness under the truck as a back up? Problem is that it was only doing 5/10. Not sure that's even enough for a backup.

it will work, just got to get hardware to hook up to raptor stuff. weak pump is better than no pump for backup. the fuel boss has the stock pump inline for automatic backup. and you can tell it will be on as it does 8psi max.

[1slow24]

Mine sits at 20-21 and at WOT it will maybe drop a pound. Unless I'm under a 1/4 tank (rarely) and it will drop to around 18

[Utah Dually]

20 - 21 Idle - WOT 14-15

[Matt0matic]

22-24 at idle, 19 WOT

[kingairc90c]

19-idle, 15-wot

[Utah Dually]

When I ordered my Raptor from Vulcan I ask for the fittings to put on my Carter as a spare so I could duck tape it in place of the Raptor just in case it failed out on the road when I was towing. I am even thinking now that I just might get an extra Raptor to put in the trailer. Since I am towing a race car I always have spares and tools with me. Just good insurance because I hate being broken down in some small town and being at the mercy of who knows who...

[Texas CTD]

Well, I'm kinda tired of 9 PSI at idle, and then the fuel pressure fallows the tach. (1,500 RPM = 15 PSI, 2,000 RPM = 19-20 PSI)So to get it right, I would need to run dual return lines, and buy an adjustable regulator. :spend:On top of that, it drips a little oil out of the pan bolts. (very little oil. I lose more oil when I wipe the dipstick off)And it's pretty hard to prime, especially if you're by yourself. When I was looking for a lift pump, the Assassin looked like a pretty good deal, and it was, and all I read was good things about it, and I liked the simplicity of it. In a way I still like it, and I guess if I had the money, I could make it work. But, instead of spending money on it, it's time for a FASS HPFP.I guess the main thing that scares me, is if my dad gets off somewhere, and a belt breaks, or something happens where he would have to re-prime it, and it being a PITA to prime, I don't want that to happen.A lot of people have had good luck with the Assassin, and I guess I've had fair luck with it, but I think for peace of mind, and more importantly, VP44 longevity, I'm going to get a FASS.

[Gamble]

I hate to hear you are not a fan of the assassin. Unless you have a leak in the line you won't lose prime if a belt breaks, as a matter of experienced fact, the truck will continue to run because the VP will vacuum pull fuel. Definitely don't want to do that for long but ot will. As for priming, the initial prime was the only time I have had to prime mine and it primed in a very short time when I filled the fuel tank with air. The drill option will take a little longer. I too have the small oil loss but I keep mine clean and it hasn't ever been enough to even make a drop on my driveway. I am not sure why your pressure is so low on the idle side, I still sit at 13-15 idle and 20-21 anytime above that. Good luck. On the flip side I am not sure if your in an auto or manual as I can't see sigs at the moment, but my manual is obviously going to idle higher than an auto so maybe those 3-400 rpms are the difference in Idle pressure.

[Texas CTD]

I hate to hear you are not a fan of the assassin. Unless you have a leak in the line you won't lose prime if a belt breaks, as a matter of experienced fact, the truck will continue to run because the VP will vacuum pull fuel. Definitely don't want to do that for long but ot will. As for priming, the initial prime was the only time I have had to prime mine and it primed in a very short time when I filled the fuel tank with air. The drill option will take a little longer. I too have the small oil loss but I keep mine clean and it hasn't ever been enough to even make a drop on my driveway. I am not sure why your pressure is so low on the idle side, I still sit at 13-15 idle and 20-21 anytime above that. Good luck. On the flip side I am not sure if your in an auto or manual as I can't see sigs at the moment, but my manual is obviously going to idle higher than an auto so maybe those 3-400 rpms are the difference in Idle pressure.

I've had my regulator apart probably 50 times, attempting to get my pressure set right, and I usually just shoot a little air in the tank and close up the banjo, and it's good to go, but one time my needle valve was loose, and it completely lost prime, and it was a PAIN to re-prime. The other day I was doing regulator work, and it was real hard to re-prime for some reason... The oil isn't that big of a deal really, but it'd be nice if it wouldn't leak. Manual, so that's not the problem.

[Texas CTD]

So for the past few months I've had about 8-9 PSI at idle, and if I was hard on it, and shifted at 2,500 RPM (<-- I never do that, except for that one test) I could get it just over 20 PSI. Cruising speed (55 MPH) I had about 15 PSI. A couple days ago I threw in a very thin washer (shim) and now It idles at a solid 12 - 12 1/2 PSI, and I've got 20 PSI by about 1,600 RPM, and after that the regulator starts regulating, so if I'm hard on it, I can get it over 25 PSI, but driving like a sane person, it'll max out at about ~23 PSI while going through the gears.Better than nothing.....