The liquid definitely makes a difference as far as pressure reading goes. Aeromotive gauges, which are made by Auto Meter, have a release valve that you open to equalize the pressure. I didn't read the directions at first and couldn't figure out why my pressure reading kept changing. It was the hot and cold of the engine compartment messing with the liquid. Once I opened the valve it settled right in.
Many of these gauges have a rubber plug (used to fill them) that you can "burp" to let out excess pressure. I found that by letting out about a third of the liquid cured the problem for me.
When it gets hot, the liquid expands, but the liquid can't compress. If you replace part of the liquid with air, then the expanding liquid will compress the air instead of pushing the gauge diaphram. Sent from my iPhone using The H.A.M.B. mobile app
I've been running a cheap chrome Holley gauge and regulator for 4 years. 3 different motors. Electric and mechanical fuel pump. No issues.
Not sure if their still the same design but I also had good luck with a Holley gauge years back mounted on the engine, blown 302 Chevy, buzzed it pretty high. Went through a couple that seemed to skip teeth. Tried a liquid filled gauge that did the low pressure thing when hot before I knew what the deal was and the glycerine also turned dark after a while. Unfilled Holley worked like a champ and the needle even stayed pretty steady with the vibrations, almost seemed internally dampened somehow. Thought I'd edit this to clarify that the initial two gauges I used were not Holleys, just the last one.
I had a new gauge from Summit, and it failed before I was done breaking in my cam. Mechanical pump and it pulsed continuous until the gauge filled with fuel and ruined the numbers on the face. It's lifespan was measured in minutes. I pulled it off and replaced it with a plug. I don't trust a gauge filled with fuel.
I run three Stomberg 97s fed thru a holly low pressure fuel regulator and monitored by a quality Earle's liquid filled fuel pressure gauge. When I first ***embled this system, I had the same problem. When the engine started the pressure was 2.5 to 3 psi., just as I had set the regulator, and the engine ran perfectly. However, as the engine began to heat up the pressure gauge showed low pressure and finally no pressure at all despite the fact the engine ran great. I even drag race the car sometimes and run in the 13s. So clearly the pressure gauge is showing a false pressure reading after the engine warms up. I just check the pressure when I first start the engine; after that I ignore the gauge. I asked Earles about it and they had no idea what was causing the problem.
The Jalopy Journal
