FASS 150/180 pressure question...

Extended Power

Extended Power

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Joined
May 19, 2006
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When I first bought my FASS, it only made 45 psi. (It was supposed to be 55psi)
Dan sent out a new spring, and fitting for me, and I was able to dial it down to 60 psi.

At the time, I had a regulated return system on it.

Now, I am only using the FASS system with it's return line only...no more regulated return line from the front.

I put the spring, and fitting that was originally in the FASS back in, but now, the pressure is down to 45 psi again.

I can't put the other spring and fitting in, because the pressure will go to 80+ psi. (Remeber, I am not using the regulated return anymore.)

What can I use to "shim" the spring up, so I can get back to 55-60 psi?
 
get a hold of Dan from fass, he should have a 60 psi spring for you. I had the same problem with just 45 psi then he send me a new spring that brought the pressure to 60 psi.
 
Well, I did PM him before, and he did send me another spring and fitting for the "Regulated"system, but it has WAY to much pressure now that I am not using the regulated return stuff. (I am using the FASS return thou)
 
Extended Power said:
Well, I did PM him before, and he did send me another spring and fitting for the "Regulated"system, but it has WAY to much pressure now that I am not using the regulated return stuff. (I am using the FASS return thou)
Click to expand...

see if he'll send you a 60psi spring, now that you are not using a regulated system.
 
I would throw the regulator back on there and get that pressure down..but thats just me.
 
80 is gonna be too much. You can also get a flow restrictor and throw it inline just after the fass, and it will stay at 60, or whatever you want.
 
Get a hold of Dan I've got mine set up using the FASS as the regulator and it sits solid at 60psi without flinching, just need to switch springs, but I'd run the 45 till you get the right one.
 
While I agree in theory, you don't need a regulated return with a system like the FASS, it sure helps when dialing in exact FP's. The FASS does regulate by design, but not to the detail that we need in these trucks. Tim's idea of an adjustable restrictor(valve) or the like, is a good idea and something I've tested. It works great and would actually be a good addtion to the FASS system itself. Low fuel pressure in a CR is acceptable(never a good idea) and normally won't cause any damage. In an HEUI, fuel pressure is critical to the life of the injectors.

The regulated return designs just make sense. They flow more than enough fuel, allow for adjustability, and also for changes in pump or pump design in the future without rerouting all your lines again. That being said, I'm sure you can deliver enough fuel either way you decide.
 
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