Noisy fuel pressure regulator

Okay, I've been running a dead head fuel pressure regulator for ever. Ever so often, it starts making a vibrating noise.The regulator has rubber grommets to reduce noise. Thinking of going to a by-pass regulator. Question: By-pass line should be the same as pressure? Any issues with using the 1/4" vent line on the sending unit as a by-pass? I run 1/2" pressure line to the regulator, then 2 individual 3/8" lines to the carb. Thanks for any input..

There needs to be no back pressure in the return line. It should be the same size as the feed line or preferably one size bigger. No tight bends or pinched line. The return line should exit close to the bottom of tank below fuel level to prevent aeration and away from the pickup.

return should be as big or bigger than feed line .
1/2" to reg , 1/2"return .
In saying that I used 3/8"return , into tank sender , for years . But when I finally went to 1/2"return I had to readjust fuel pressure a little higher . That tells me the 3/8 was a restriction .

Tex

do you need a 4 port or 2 port regulator?

I just want the regulator to be quiet. If there is a way to tone it down a bit, I'd go that route.

Is this noise audible with the engine running or is this with engine off and 100% deadheaded? where and how is the regulator mounted? Hard lines or hose connected to the regulator? Vane pump or gerotor? Does the noise coincide with abnormal pressure fluctuation?

If the regulator is mounted to the body the sheet metal amplifies any noise like a speaker. If mounted to the intake manifold(which is popular) it transfers engine vibration to the regulator potentially affecting the operation of the regulator. I prefer to let the regulator hang from the hoses, isolating it from any hard objects or vibration.

Any chance that it is a bad pump, filter or pickup causing fuel aeration or cavitation that is rattling the regulator?

A gerotor pump and bypass regulator will always be much quieter than a vane pump and deadhead regulator.

What kind of noise is it making?

I have a Mallory pump and standard deadhead regulator mounted to the inner fender. AN lines in and out. At times the regulator makes a vibrating type noise. Kind of hard to explain. If I shut the pump off, the noise goes away. The pumpis located at the rear of the car and is quiet when running. With engine running, at times you can hear the regulator making the noise. When it makes the noise, the fuel pressure is stable. I had it mounted with rubber spacers. Yesterday, I installed two rybber insulators from my MSD. Seems to be better, but I have not driven the car yet since doing this?

Pm robbmc on here or email robb@robbmcperformance.com

He was an engineer for Mallory. He has answered fuel system questions on here many times and might have some insight on your noise issue.

I've had a few regulators do this on a few different pumps / systems, doesn't seem to matter what brands. It's usually worse on first "fill" or first start up then settles once pressure does. Latest system is Magnafuel 500 (Bypass at pump) and Aeromotive pro stock 4 port reg. Doesn't seem to do any harm?

In general, the return line should be the same size as the supply line.
On Carb (lower fuel pressures) you need very low restriction back to the tank (supply line size or larger) because that will be the lowest pressure you can adjust the regulator for (when the pump is full output, and no fuel going to the carb float bowls.
An Example would be when my '71 Charger was running the Mallory 250 pump (full flow) with 1/2" supply and return lines. I think that pump puts out around 20 psi un-regulated?
It was difficult to set the By-pass regulator pressure (at the engine) at idle because it was by-passing so much fuel the lowest pressure I could get was 7-8 Psi. Because the pump has a built in bypass regulator, I used it to bring the pumps output pressure down to maybe 12-15psi, then I could adjust the by-pass regulator at the carb for 6-7 PSI

On EFI (high fuel pressure) you can usually be OK with a return line one size smaller than the supply line. With EFI pressures usually around 3 to 4 bar (43.5 to 58+ psi) a little pressure in the return line is OK.
For example, if the restriction in the return line is 10 to 20 psi that is still much lower than the EFI regulated pressures of 40+ psi, but would be way too high for a carb requiring 5-7 psi.