Those of you p-pumped with a FASS system...

GOT-Torque

GOT-Torque

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If you use a FASS system to provide the fuel pressure to your p-pump, can you just provide the fuel to the pump and cap the return?

I was thinking of running the output from the FASS to a "Y" fitting, then feeding both the stock inlet and stock return on my pump. Since the FASS is regulated, does this cause a problem?

Does the P7100 pump use the fuel for cooling at all?

Also, at what hp level does a 1/2" fuel line become a restriction? It's 1/2" from the drawstraw to the pump. Drawstraw may even be 5/8", I can't remember...
 
I have no idea, I'm still learning. Got a quote from Dan to upgrade my current FASS to a 200 gph unit with a 45 psi spring.

Since I don't know what pressure I really need, maybe you guys could enlighten me with what pressure you run?
 
GOT-Torque said:
Since I don't know what pressure I really need, maybe you guys could enlighten me with what pressure you run?
Click to expand...


I found running 45-50 is the key,

My personel experience is the truck runs better with that PSI
 
Far from an expert on a complete answer but I can tell you yes, the pump does use recirculation of fuel to cool. I don't think it is a workable plan, but may be wrong.
 
I have ppumped 2 2001's and both are at 45 psi with fass pump 1/2in draw tube and 1/2in fuel line, with modified stock return valve on ppump. They work great and never drop below 40psi down track.
 
Tom and 01PPUMP, so you both recirculate fuel thru the stock return valve?

What exactly is the fuel return valve? Just an orifice to create the fuel pressure within the pump? Or is it adjustable?
 
The Overflow valve is on front passenger side of the pump it is a spring and ball setup that can be shimmed to change the psi. Its the fitting that holds the return line to the pump. Your plan doesn't sound like a good idea to me. Its never good on anything when you dead head a system.
 
Loud&O is correct DONOT delete the return, fuel needs to circulate for cooling and lubrication. You can shim the stock return to raise pressure or buy an adjustable valve both ways will get you to the same place. Hope this helps.
 
Keep the info coming...this is only part of the swap I don't understand yet.

From what I gather thare is two inlets on the P7100? some feed them with separate pumps? this is the part I need to hash out as its gonna take the longest to get worked out in my swap.
 
I would not worry about a dual feed setup, just run it to the stock inlet at 45-50psi and return out of the stock return location with the overflow valve, and call it a day. I would recommend the 200gph FASS.

-Tom
 
OK, so whether I run a dual feed or not will be decided later, but as far as the return...

Is there a proper amount of return fuel flow that is ideal?

I'm going to guess the stock fuel return (ball/spring) setup was there originally to regulate the pressure from a stock 12V lift pump setup (keep pressure built up in the pump and also keep it from getting to high). If you go with a self regulating setup (like a FASS), it will always put out 50 psi (or close to it), so the fuel return valve could be set to limit return flow or allow alot of it. How does it do in stock form? In other words do I need to adjust it at all?

Thanks for all the info so far, it will be a learning experience for sure.
 
I run a regulator on my return line. It is a 1:1 boost rise. Fass has a 45 psi spring in it. have the regulator so it is about 28 psi at idle, and every pound of boost brings a pound of fuel pressure. Once I reach 45psi of fuel pressure the fass starts bypassing.
 
is there are advantage to doing it that way vs. just having 45 psi all the time? just easier on the pump maybe?
 
I just fired mine off the other nite but im not finished it yet, and it was running 40psi from the fass with a 1 hole overflow valve, and I tried just to test crimping the return line on the FASS and the pressure went up a good bit not 100% sure what it was as I was by myself and could barily see the gauge.might have been 60lb or so. Anybody ever ran theirs like that with the Fass return closed of for a 13mm pump?
 
Yeah same thoughts here, but I'll see what kind of pressures it maintains with the 13mm on Kill, and maybe just do that when compeating if the pressures dont maintain. Tom's running just a Fass with his SIGMA?
 
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