I have the Mallory 4309 fuel pressure reg for my carb setup. I can't seem to get any adjustment out of it - right now my fuel pressure guage reads 13psi, and the only time it changes is when I turn the screw all the way in til it stops, then I get 15psi. I thought the Mallory 4309 was supposed to be 3psi - 12 psi - what gives? No matter what level I have the fuel flow (I pinched the hose slightly with vice grips to decrease fuel pressure) - I can at best get an adjustment of 2psi, and that's up - no downward adjustment at all. Am I routing the fuel lines right? How is everyone routing their fuel lines on the Mallory 4309 regulator? I have mine with feed line going into side, then out of other side to pressure guage, then out of pressure guage to carb, and the return line is connected in bottom of 4309. Like Pic 3B in the directions: http://go.mrgasket.com/pdf/4309.pdf Is this how everyone is connecting it? Maybe my regulator is bad (it's only seen 500 miles, and all of them no adjustment was ever possible with it). Any info appreciated!

did you try something other than those tiny little crap $15 guages that summit sells? my $15 guage isn't worth a damn and I went to an autometer one mounted inside my cowl hood

Yeah - I tried 2 - an elcheapo from autozone, and my nice Summit liquid-filled guage - both showed same reading - my FPR is toast, which makes me mad - it's got less than 500 miles on it, but it's past it's 90 day warranty! Know that Mallory gets a piece of my mind on Tuesday!

the "nice" summit liquid filled is still those cheap crappy ones. go get a snap on guage, or an autometer and check back with us. it also might be due to a TPI fuel pump and an inadequate return line size or a restriction in the line. i don't think it's a faulty pressure regulator. furthermore, if this is a holley carb, there would be fuel DUMPING off the needle and seat if the pressure was indeed too high as 9psi is the limit until they open up

Well, it's not a TPI pump, it's a TBI pump, and stock lines. Since the first day I put the guage on, I could only adjust it by 2-3 psi, but I was getting the same pressure readings from 3 different guages (between 5 and 7psi), so I left it alone. This week, my oil pressure sending unit died, and I decided to replace the fuel pump since the car has 170,000 miles on it - and in the process the regulator is just another one of my problems - when it rains problems it pours in my world! I'll try a better guage, but I'm assuming these pressure regulators do go bad (or come from factory bad) since they sell a rebuild kit for $25

the rebuild kit is for the diaphragm, since sometimes they can dry up and leak, i'm not sure that it includes a new pressure spring or not. try blowing air into the return line to see if there is a restriction somewhere. I'm running a 130gph pump that maxes out at 14psi and i can regulate it down to 3psi no problem, although i run it at 8psi. I also am running 1/2" send lines and 3/8" return lines that are much larger than factory, although my pump is about 4 times more flow than a TBI pump at least as well. Don't worry everytime I pull out my car from storage I figure it'll cost me $300-400 in parts that have gone wrong or i'm not happy with every spring....this year I'll be spending $690 plus shipping, and my list isn't even complete yet.

Did you ever solve your problem?

Easy way to tell would be to take the adjuster screw all the out and put power to the pump. Mallory recommends that procedure for checking your return line size. Obviously you've ran it before so you should be fine on the return size unless it's plugged or the regulator is just plain dead. They said 3 PSI and under is fine in the directions when you take the screw out. If you're higher than that I would look at the return line first.

My OEM replacement TPI pump runs fine with 6 AN hoses off the hardlines to 3/8" adapters on the AFPR. I see right at or barely under 3 psi with the screw removed.

Fireturd350 - thanks for the info - I missed that part of the directions from Mallory - I'll try it.

I did get adjustability back in the 4309 - but I'm still having issues. Please see my new post titled Carb Issues - too stupid to know. Thanks.