Fuel Pressure Regulator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

magwakeenercew2jh · 02-02-2014, 05:46 PM

For right now, I'm running a Street DeMon (625 cfm) with an electric fuel pump. It is, I believe, running the fuel pressure too high.

I have a gauge on the line right before the carb. While everything feels and appears to be working perfectly, as far as drive-ability goes,
the pressure gauge is pinned (15 + lbs) when the fuel pump is on. Same reading while the truck is running (while carb is drinking

).

Although there are a good test-number of miles on this combo of fuel delivery on RAT (probably 350 +/-) I've noticed a little yellowing
around the carb.... so I think I better ask for tips on a good fuel pressure regulator before I blow something out in the carb....or worse.

What do you use? I'll check the DeMon book for their suggested pressure, but what pressure do you all like?

**Boog** · 02-02-2014, 06:12 PM

Bill checking with Demon is a good idea but stock quadrajets are recommended to be no more than 6 or 7 psi.

magwakeenercew2jh · 02-02-2014, 06:19 PM

Quote:

Originally Posted by Boog

Bill checking with Demon is a good idea but stock quadrajets are recommended to be no more than 6 or 7 psi.

Yeah, thanks, Boog.

I did check just now and here's what they "say",

"Demon recommends between 5 and 6 PSI fuel pressure at idle. Gasoline carburetors can be run either at idle or wide
open throttle at these pressures. Be sure your fuel delivery system is properly adjusted and able to maintain volume flow
at these pressures. Improperly adjusted or inadequate fuel delivery will result in poor performance and possible engine
damage."

I best get a fuel pressure regulator....

Lookin' for input on a decent one....maybe an adjustable?

vidman · 02-02-2014, 06:24 PM

Set my Aeromotive at 6.5 lbs on the dyno with a Holley and all was good. May have to adjust it a bit once it hits the street..

Lattimer · 02-02-2014, 06:52 PM

I run a street demon and found it really likes 5.5 psi. I bought a basic regulator from Jegs and it works fine. I have a gauge between the regulator and the carb and it's set to give 5.5 psi at idle. Higher pressure is hard on the float needle and can cause flooding.

I run a mechanical pump.

picklito · 11-10-2015, 01:26 AM

I've got about 500 miles on my Street Demon 625cfm. Stock mechanical fuel pump on a stock 402 bbc. My experience is that the mechanicals run about 8psi but I haven't checked this one yet. That's certainly not terribly high, but it does run a little rich in stock tune and that seems to be what I'm hearing with the Street Demon. Seems like a good candidate for a fuel pressure regulator and gauge, then some jetting. Otherwise, this is the best out-of-the-box carb I've ever used. Really liking it.

02-02-2014, 05:46 PM	#1
magwakeenercew2jh RAT1968 '68 Cab/'71 Parts Join Date: Feb 2002 Location: Coarsegold, CA Posts: 2,375	Fuel Pressure Regulator For right now, I'm running a Street DeMon (625 cfm) with an electric fuel pump. It is, I believe, running the fuel pressure too high. I have a gauge on the line right before the carb. While everything feels and appears to be working perfectly, as far as drive-ability goes, the pressure gauge is pinned (15 + lbs) when the fuel pump is on. Same reading while the truck is running (while carb is drinking ). Although there are a good test-number of miles on this combo of fuel delivery on RAT (probably 350 +/-) I've noticed a little yellowing around the carb.... so I think I better ask for tips on a good fuel pressure regulator before I blow something out in the carb....or worse. What do you use? I'll check the DeMon book for their suggested pressure, but what pressure do you all like? Attached Images __________________ M17 Coarsegold, CA RAT's shiny now. But always a rat.

02-02-2014, 06:12 PM	#2
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,513	Re: Fuel Pressure Regulator Bill checking with Demon is a good idea but stock quadrajets are recommended to be no more than 6 or 7 psi. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

02-02-2014, 06:24 PM	#4
vidman Registered User Join Date: Jun 2012 Location: Fitchburg,Mass Posts: 737	Re: Fuel Pressure Regulator Set my Aeromotive at 6.5 lbs on the dyno with a Holley and all was good. May have to adjust it a bit once it hits the street.. __________________ 62 Willys 4wd Pickup : 72 C-10 swb 504 stroker 09 Taco 3" lift 33" tires: 90 K-5 blazer (plow truck): RIP Ross Little brother

02-02-2014, 06:52 PM	#5
Lattimer Registered User Join Date: Jan 2013 Location: Mickleton, NJ Posts: 1,776	Re: Fuel Pressure Regulator I run a street demon and found it really likes 5.5 psi. I bought a basic regulator from Jegs and it works fine. I have a gauge between the regulator and the carb and it's set to give 5.5 psi at idle. Higher pressure is hard on the float needle and can cause flooding. I run a mechanical pump. __________________ Shawn 1970 Chevy C-10 SWB, 350, TKO 600 5 speed My build http://67-72chevytrucks.com/vboard/s...d.php?t=559881

11-10-2015, 01:26 AM	#6
picklito Registered User Join Date: Sep 2013 Location: Vacaville CA Posts: 490	Re: Fuel Pressure Regulator I've got about 500 miles on my Street Demon 625cfm. Stock mechanical fuel pump on a stock 402 bbc. My experience is that the mechanicals run about 8psi but I haven't checked this one yet. That's certainly not terribly high, but it does run a little rich in stock tune and that seems to be what I'm hearing with the Street Demon. Seems like a good candidate for a fuel pressure regulator and gauge, then some jetting. Otherwise, this is the best out-of-the-box carb I've ever used. Really liking it.



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