There is no "chemistry set" method to measure fuel vapor points. Though I once has it working with only two 0-140 regulators, and since I had messed with the 0-140 regulator on the carb feed side trying to get it to work previously - it popped up to 50 psi - but the 15 psi reg held at 9 psi to the carb - for about 5 minutes, until I tried to reduce the 0-140 below 50 psi. the cause for your fuel pressure fluxuation is because the fuel pressure is bumping up against the regulator and the extra fuel has no where to go , the quick fix is run a return line . http://www.frontieroil.com/attachments/contentmanagers/106/PrdctsSpec_UnleadGasSpecs.pdf. By 1913 it was the other way around. Use with standard pump only - not recommended for maximum pressure pumps. This item cannot be shipped to your selected delivery location. Any thoughts on this? Holley 804 fuel pressure regulator install - YouTube 0:00 / 5:58 Holley 804 fuel pressure regulator install Schnebs Garage 2.42K subscribers Join Subscribe 72 Share Save 15K views 3 years ago. This Holley FPR (12-804) use to be a perfect choice to solve the "too much fuel pressure" produced by the aftermarket fuel pumps on vintage VW. How to adjust Holley regulator? | Team Chevelle Mounting Bracket Included. I have a electric pump at the tank to try and speed up the fuel cooling process but if you have a 100 deg F day you may have fuel near 100 deg F in the tank. Free Shipping - Holley Fuel Pressure Regulators with qualifying orders of $99. September 21, 2010 in Technical. Works, don't use a liquid filled gauge in an engine compartment! Once the fuel fills up the float bowls in the carburetor and the needles and seats shut, it starts to build pressure, pushing the diaphragm against the adjustment spring under the adjustment screw and allowing the ball to go "up" against the seat, effectively shutting off fuel flow to the carb. Decrease pressure by turning the adjustment screw counter-clockwise. Find an Automotive Service Professional In those days before 1905 kerosene had a strong piercing odor and coal oil lamps sometimes exploded. 4.9. ,