I have a 454 with headers and a Holley Mech Pump that requires a regulator when I start the car I have about 7-8 PSI of pressure as it starts to warm up it goes down to about 41/2 PSI. I check the fuel line even the one that are closest to the headers are cool, I took apart the regulator it was clean, new fuel filter, the pump feels pretty hot could the fuel be vaporizing in the pump?? I can also see small bubbles going into the fuel filter?? any help would be appreciated, David

Fuel pressure usually drops after my car warms up,and its hard to regulate when you deadhead at the carburetor. I've been chasing mine lately and thinking about going to a circulating system.

David I had a similar problem,but mine was caused by the liquid filled gauge everytime the engine got warm the gauge would give a false reading,swithed gauges and now I have good fuel pressure only took 2 weekends to fiqure it out graemlins/clonk.gif

If you are using a liquid filled gauge, they are inaccurate when they get hot. You can check this by peeling back the little rubber nipple on the side of the gauge when it is hot and you will see the pressure come back up. Only peel back the rubber piece a little bit or some of the liquid will spill out.

Yes I am running a Summit Liquid filled gauge screwed into the carb fuel line, I will try a different guage, actually thinking of a autometer mech gauge or a inside gauge with the Isolator, has anyone had any experiences with the isolated gauge good or bad?? Thanks agian David

P.S. If I drain the fluid in the guage I have now will it operate properly then?? (just temporary) David

I don't know if the guage will work if you drain it but it's not going to hurt it,it's not working right anyway! graemlins/waving.gif

I am glad I found this post because the same exact thing started happening to me. I was racking my brain to figure out why the pressure reading would start too drop.I too just got the liquid filled summit gauge.When I started the car fuel pressure read fine but as it warmed up the gauge read less.

So can I just empty out the liquid in the guage and will it give an accurate reading? or do I need a whole new gauge? I suppose the gauge works fine just not when it gets warm