Mallory 4309 fuel pres. regulator is inconsistent

[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.