Quote Originally Posted by jerry clayton View Post
If your fuel pressure guage is near the carb or anywhere near the engine where heat will effect it-----it won't be consistant and/or accurate--------you will only rear pressure that the needle/seats hold closed and it will read less where they are passing fuel...
I don't disagree, but the effects of ambient temperature, the temperature immediately around the gauge heating up the gauge internals, does affect the accuracy but won't affect the repeatability or consistency of the measurement if it's a good gauge. For every 18F that you increase the gauge temp (temperature of the bourdon tube in the gauge, not just the surroundings) above the calibration temperature you'll affect accuracy only about plus or minus 0.04%. If a gauge was calibrated at room temperature, say 70F, and the gauge is operating at 360F consistent ambient then the accuracy of the reading will be off by as much as 0.65% which means that a setting of 4 psig may be 3.97 to 4.026 psig, well within acceptable margins for carb fuel pressure measurements.

If the gauge shows a dip in pressure as the needle pulls off the seat, that is showing that the regulator is not responding quickly enough to maintain flow.

I'd still be looking at the regulator, especially based on 36 sedan's experience.