How much fuel pressure is too much?
 

I had a problem w my FASS 180, so I ordered a replacement pump. It came in today, so I installed it and primed the system.

Once the truck fired, I noticed that my 30psi fuel pressure gauge is now pegged. Before the replacement pump, I had 25psi at idle and around 21 when I was on it.

Is this too much pressure for a II hot rod 44?
It starts fine and idles, but I haven't driven it yet.


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25 is way more then enough and if the gauge is pegged now I'd def find the cause of it befor it hurts the pump.

Thanks. Somebody told me that a lot of guys run 50psi. That seems like a ton to me.

I was told that there is a screw you can adjust on the FASS to reduce the pressure.

Has anyone done this before?


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Yea 50 psi on a p pump is normal and if yours is adjustable its easy to do, just loosen the jam nut and adjust the allen screw to your desired pressure and tighten it back up. Fass reccomends 8-12 psi but Id be shooting for 20

RR, this is on a VP44. I'm not sure how much different it is than a p pump, but supposedly you can change a spring or adjust a screw on the FASS to reduce the pressure.


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The two pumps are very different. The recommended pressures listed above are for a VP44.

I just swapped in another gauge, and it's reading 40psi!


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That just doesn't seem right at all! How old is your pressure relief valve in the return port of the VP? MIght be a good idea to change it, and adjust the FASS. What FASS do you have again? I'm not finding a 180.

I may be confusing the Airdog 180 on the Ford. It's a FASS 150. I checked the return valve and it looks good. I just cut the spring in the FASS and it dropped to 31psi. I'm going to cut it a bit more and try to get it to 20-25psi at idle.


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I finally got it to idle at 23-24psi. I'm surprised how much of the spring I had to cut!

I think I'll order another spring and ball to keep as a spare.

I don't know why FASS doesn't make an externally adjustable bypass instead of the internal spring. Kinda a PITA to get it right:(


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I'd get a hold of FASS and tell them the situation. chances are they will send you a new spring free of charge.

I have a raptor 150 that the p.o. Installed. I stay pegged at 30 plus. Is it bad to run it that high? So far I've gotten mixed opinions some say not to worry fuel will just return others say you can blow the injectors out (stock, which mine are)

Can't effect injectors, but high pressures have been known to cause hard starts. Anything over 20psi has no positive effect. The raptor 150 has a set screw on it, I'd drop it down to 18psi at idle if I were you.

I just replaced the return valve and that helped thing out also. The old valve was really soft compared to the new valve.

It sits at 22-23psi now.

Here's a quick question about the plumbing.

I noticed that everything was plumbed in -8, and confirmed w FASS that this is correct. It seems small to me. On my 7.3, I ran a -12 pick up from the tank to the FASS, then -10 to a Y. From the Y, I ran -8 to the heads.

Is there any advantage to running -12 to the FASS and -10 to the IP?

Also, has anyone removed the return valve and installed a fuel pressure regulator? Would this make any difference?


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I was told by II that more than 20psi will cause the IP to wear faster and could cause hard starts.


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