Fass Pressure
 

ok installed the system and I am getting 12psi but it's not constant it's bobbling between 12 and 10. did I mess something up or what do I need to do to start?

24v should be getting 15psi IIRC with an aftermarket lift pump. Where is your fp tap?

in the side of the injection pump where edge puts it for the attitude monitor. I am running a bigline kit so I have the highflow banjos in already.

I don't have any experience with the FASS in particular but for the fluctuations there almost has to be a problem with the pressure regulator, be it internal, in line or mechanical one I don't know what you have.

new spring on the way to fix the issue

The spring on the FASS is likely not the problem. The pressure when read off the VP like that can be the sign of internal troubles ahead with the VP44 or it could be a problem with the FP gauge set up. Test the gauge against another.

Change the fuel filters, inspect and drive to see if it comes up but you should see more than 12 and normally more than 15 psi at idle.

I see 17 at idle with my FASS 150.150 and 13 at WOT.

brand new system. my holley blue was putting out 15 then it died. the fuel pressure should not fluctuate like that from what I was told. I called my dealer and said that there has been an issue with the spring from the return line and he would send one out today. he originally was going to put one in before sending out but didn't think about it when he shipped it not a big issue to me. it runs fine but should not be dropping down to 8 9 psi. so it seems like the spring may be weak and not letting it build enough pressure. when I cycle the key the highest pressure I have had was 13 from the fass but the holley I had on it was making up to 15 right before it was pulled.

ihad the same issue and outcome. changed the spring alls well. i see about 14 at idle and halfway thru the pedal, then dips a little lower at wfo.

thats good to hear. the shop I got it from stated that was a problem on some and thats why he was thinkin of changing it. seems to smoke a lil better now though. guess full on fuel supply helps.

No the pressure shouldn't fluctuate like that. Now, replacing the spring may be the answer according to your dealer but I've just never seen that. Anyway, I would check your gauge setup (Juice) against a mechanical annalog gauge under the hood. This will tell you if the pressure is actually fluctuating.

You should still do this even after the spring is replaced just to be sure the Juice system is working as it should.

You may need to install a snubber valve between the VP44 test port and the edge connector. You may also need to replace the sending unit on the juice.

Just trying to help is all.