Here's the deal: have been running the FASS 150 system plumbed through the OEM filter canister, plus the in-tank OEM pump. Pressure at the CP3 has been steady at 20 psi, with a drop to 18 PSI under load at hard throttle. Started getting concerned that when fuel level fell to about 1/8 tank, the FASS would get a LOT louder - fill the tank, quiet as a mouse.
Was told by a performance vendor here to disable the in-tank pump, and install a DrawStraw (3/8"), that the OEM pump was starving the FASS. So, today I did that. Installed the DrawStraw, and disconnected power to the OEM in-tank pump. Now pressure at the CP3 sits at 16 PSI, drops to 12-14 under moderate throttle, and drops to 0-4 under load (uphill) at hard throttle. And Im getting injector clatter under light throttle/cruise - more pedal makes that go away.
Did I screw up by running just the FASS 150? Ideas?

 

Are you below a 1/4 tank of diesel? Some of these fuel systems run into a little trouble at or below a quarter tank.

 

bump
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First off....NEVER run the in-tank pump with the FASS. Bad things can and will happen. Your vendor did you a favor.

As for your pressure. You should be about 13-14 PSI idle as per our springs we use. The 4-0 PSI reading at WOT tells me we got maybe 2 things going on here:

• Gauge reading incorrectly ( I see this one the most)
  
• Restriction somewhere inline before the gauge tap or running out of fuel.

How fresh is your stock filter? I have seen these cause issue.

Where was the Draw Straw mounted? In the tank or module?

Im assuming this was a Draw Straw II? If you are pulling out of the in-tank pump module with the Draw Straw, you could still be empting the cup under half a tank of fuel. The refresh rate on these cups are very slow...so a 150 GPH pump can out run it.

Make sure you are not sucking any air at the suction fittings.....

Check some of those things out and let me know what you find.

 

I have just order the FASS 95 with filters from Smith Diesel yesterday. Is the Fuel Pickup tub a ridged pipe or similar to a Glacier setup. I can’t believe that Dodge has de-tuned these trucks for additional power by limiting the fuel flow. I towed my 10,000 pound 5th wheel this past weekend (97 deg. & 6,000 to 7,000 feet above sea level) with no power to muscle up the hills. I have owned a 97 and 2000 Ford 7.3 liter with far less mods that would flat out run most 5.o Mustang light to light and pull the same trailer up any mountain pass in new mexico, colorado, flagstaff, texas and/or calif. I am running afe stage 1, torque tube, cat delete, mrp muffler, gaud xlt, commander, ats vb,ats arc flow.I did call Smith Diesel when I reached my distination friday afternoon and coundn't believe that this truck was running out of fuel pressure. I was pretty unhappy with the performance of my 07 4x4 mega cab when loaded. kyle at Smith Diesel has been very helpfull and informative. I realy enjoy this truck when i am pulling my construction trailer around town but when I want to pull my 5th wheel for a little R&R I like to maintane my speed up the hills.

 

I cant comment on the GDP pickup since i have never seen it. BUT ours is very similar to the Draw Straw II that Vulcan makes. Its a ridged pipe that is set up at the very bottom of the tank.

Kyle at Smith Diesel is one of my above average dealers....you will be very happy with him.

 

there is supposed to be a fix call fass

 

In order:
Gauge reading incorrectly :
Hooked up my mechanical gauge in place of the electric - readings w/in 1 psi.

Restriction somewhere inline before the gauge tap or running out of fuel.:
Checked the lines, nothing obvious. The issue did go away when I filled the tank, so I don't think there's any restriction.


How fresh is your stock filter? I have seen these cause issue. :
Changed filter - also, see above ref. to full tank effect.

Where was the Draw Straw mounted? In the tank or module?:
Draw Straw is mounted outboard of the sending unit mounting ring; viewing furthest outboard curve of the ring as 6:00, DS is mounted at about 4:30, as close to the ring as I could get it.

Im assuming this was a Draw Straw II? If you are pulling out of the in-tank pump module with the Draw Straw, you could still be empting the cup under half a tank of fuel. The refresh rate on these cups are very slow...so a 150 GPH pump can out run it.:
It is a DSII - separate from the in-tank module.

Make sure you are not sucking any air at the suction fittings.....:
All fittings checked, seem to be ok. Also, see above ref to full tank effect.

I cut the DSII to within 1/8 inch of the tank floor, beveled from that lowest point at about 22 degrees. Per instructions, but there was no mention of an exact angle - just to cut it at an angle.

FWIW, my pump tag reads "FASS 150 Series-5418" - not sure if that means anything in this case.

TIA for any help!

 

EDIT: I Don’t know how I missed this earlier.....

OK....so im guessing this issue only pops its head up when you are down around 1/4 Tank or so?

Cutting an angle on the bottom of the tube I don’t really like. Reason is you can only pull fuel from the highest part of the cut. Meaning when your fuel level drops below the upper part of the bevel, it will suck air a lot quicker than a straight cut on the bottom.

BUT in any regard, i would not suggest running a marathon on your tank with the DSII or our STK-1001. We have found if you move the tube to a more central location in the tank, the cavitation issue is significantly reduced.

 

OK, I can't call the horse dead.
Looked at the GDP flexible tube pickup - would let me position the open end of the line centerboard in the tank, even with the rigid tube mounted off to the side. But I wonder if the flexible tube would be subject to cavitation and increase the noise from the FASS...
So here's the question: would it work to pull the DSII, cut the rigid pipe off about 3" off the tank floor, and clamp on a section of flexible line with the open end run towards the center of the tank? Anyone foresee any problems with that? And what type of tubing is diesel-resistant?

 

Honestly, i would just install it like we outline in these instructions...Page 10 and 11(If you wanted to move it towards the middle of the tank, that is up to you). You are going to want your tube inlet cut parallel to the floor of the tank and the Draw tube perpendicular as a whole.....But if you run it low enough, you will suck air. This is just the nature of these draw tubes.