Mallory 4309 fuel pres. regulator is inconsistent

[Greg Hill]

Originally Posted by bill dedman

Anybody got any experience with this regulator? I set it on 6psi and it runs there for awhile and I look again and it's down to 2psi.

Look again a few minutes later, and it's back up to 6...

It has the boost reference tube connected to NOTHING right now. Pump is a 60psi Walbro 392 and both the supply tubing and the return are 3/8."

Fuel cell is half full of gasoline; The return dumps in on one side of the top (5 gallon fuel cell) and the supply line is on the other side. No rubber foam in the fuet cell, just a big, hollow cube.

The plunger in the regulator appears to be hanging up and allowing too much fuel to return to the tank (cell.) The regulator has about 10 minutes running time on it (virtually brand new.)

Is there any significance to the strength of that spring on the inside of the regulator?

Anybody else ever had a problem like this?

I'm stumped...

Get rid of the Mallory stuff, it's junk. Been there and done that 15 years ago. Manga fuel or aeromotive would be my choice.

[Rory McNeil]

Bill, what are you using for a fuel pressure gage? I have had erratic pressure reading with the liquid filled AutoMeter fuel pressure gage, is this what you are using? If so, these gages need to be vented.

[bill dedman]

Rory, that is the one I have. Maybe that's my problem. Can you recommend a different gauge? I'll get another gauge, if necessary. In fact, I'll put a different one on there right now and see what I get. I'll let you know.

Thanks!

[Sean Marconette]

The glycerin if not vented increases or decreases the pressure of the mechanical parts in the gauge as the temperature increases or decreases. If you are going to get a new gauge just drill a small hole in your current gauge to open it to atmosphere. See if that cures your problem. If there is a rubber plug in the top of the gauge just remove the plug.

Sean

[Rory McNeil]

Bill, what I did to my AutoMeter liquid filled fuel pressure gage was to just leave the vent screw loose a few turns. It is located on the top of the gage, and is covered by the mounting cup, assuming you are using one. I just pulled the gage out of the cup, loosened the screw a few turns, and put the gage back into the cup. It`s been working fine for many years like that, no more troubles.

[Dinsdale]

It's the guage. I changed several as well as went through at least 3 regulators before someone tipped me about using a liguid filled guage. Put in a plain one and pressure is steady.

[bill dedman]

I just bought a new, non-liquid filled gauge. I screwed it in this afternoon, but Freddie (partner) was working on some wiring, so I couldn't take it out for a spin.

I'll do that Friday or Saturday (busy tomorrow.)

Thanks to everyone for all the good advice!

I'll let you all know how it turns out.