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more pressure out of fass?

729 Views 9 Replies 5 Participants Last post by  blacksmokecummins
A couple days ago I got my FASS 95/150 installed. Right now it's running at 18 PSI, but I want to bring it up to 30 PSI. I read somewhere on the forum that in order to do that you need to pull the spring out of the return port and just stretch the spring out. I did that and all that did was reduce my pressure drop at WOT from 4 PSI to 2 PSI. Am I going about this wrong to get more pressure out of the FASS? :confused013:
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you need a stiffer spring, not a longer one...should have been one included with your pump
 

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Discussion Starter · #3 ·
I had a shop install the FASS. They didn't give me anything other than the owners manual when I picked up the truck.
 

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Twist the spring tighter while your streaching it so that the outside diameter of the spring gets smaller or you can just go to the local auto parts store or hardware store and buy some diff springs an see which one gets you where u want to be. IMO I wouldnt push 30 psi to your cp3.
 

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Discussion Starter · #5 ·
And why in your opinion would you not push 30 psi to your cp3?
 

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Well FASS for one told me when i talked to them about doing it on my truck that 17psi on a stock pump was the best all around psi. They said there was nothing to be gained by increasing the pump inlet pressure past that point. A pump builder said the same pretty much, only he said dont go past 25psi. Its up to you, but i've heard of premature pump failure and blown out seals by running the higher pressure. It sounds like you should have gone with the 150/150 so you could have gotten more volume at the lower pressures. Are you still going through your stock fuel filter and where are you reading your pressure at?
 

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With stock injectors/cp-3 and a superchip I don't see how your pressure is being pulled down so far.I ran a 95 series with everything in my sig with for a yr with no problems holding pressure.I upgraded to the 150 series just for the availibilty of 2 micron filters.
 

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if you dont rune fuel through your stock fuel filter you can run as much pressure as you want theres guys on here that run up to 55psi
 

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Discussion Starter · #9 ·
My FASS is connected into my stock fuel filter container, pressure gauge right after the stock filter container on 3/8" line to the CP3. I pulled the stock filter out just to see if it made any difference, none that I could see. I can see with stock injectors and injector pump, a higher pressure to the cp3 wouldn't be needed as the demand for fuel isn't that, but I see no harm in it being set roughly 10 psi higher than out of the box either. As for the up to 4 psi drop I was seeing at WOT, that I didn't really get since people with heavier fueling demands than me see 1 to less than 1 psi drop. I pulled the spring out of the return port on the pump and streched it a bit and the pressure drop went from 4 psi to 2 psi drop at WOT.
 

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but if you run through the stock filter 25 to 30 psi is max cause ull blow the plastic screw off top on the fuel filter
 
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