Fuel Pressure Toooo High
I need help and advice. I have a 67/390 hp coupe and am having fuel pressure problems. It's and original motor and original dated carb (3811). The carb has been rebuilt 2x now by a known quality re-builder. He insisted I measure the fuel pressure based on the flooding, dumping of fuel and poor running conditions I was experiencing.
I measured the fuel pressure at 7.5 to 7.75 pounds. My rebuilder said that 4 to 6lbs, with 6 as a maximum. (GM specs indicate 5 to 6.5lbs for this carb). After 6lbs my rebuilder said the Holley will start not to play nice. The fuel pump in the car was a ac/delco replacement 40482 purchased from a well know mid-year supplier. This was NOT the "Restoration" AC logo pump, just a correct non-AC logo pump with correct long inlet shaft.
And now the saga. I purchased another AC/Delco 40482 from a conventional parts supplier. By all indications it is a USA built pump and not a China build pump. I installed the new pump and have the same readings of 7.5 lbs of pressure.
I then thought to experiment and purchased a replacement "Spectra Premium" 40482 pump. Again, this has the correct long tube inlet shaft but of course no "AC" logo. The box did indicate the pump was made in China. The Spectra pump pegged my snap-on gauge at 10 lbs and gas was coming out of everywhere on my newly rebuilt 3811.
Everyone has been advising me to install a fuel pressure regulator and be done but we all know how they look and I don't want to ruin the "original" look of the engine compartment.
And yes, I did try a different pressure gauge with the same results. I welcome your advice, thoughts or ideas.
Thanks---Stan
I measured the fuel pressure at 7.5 to 7.75 pounds. My rebuilder said that 4 to 6lbs, with 6 as a maximum. (GM specs indicate 5 to 6.5lbs for this carb). After 6lbs my rebuilder said the Holley will start not to play nice. The fuel pump in the car was a ac/delco replacement 40482 purchased from a well know mid-year supplier. This was NOT the "Restoration" AC logo pump, just a correct non-AC logo pump with correct long inlet shaft.
And now the saga. I purchased another AC/Delco 40482 from a conventional parts supplier. By all indications it is a USA built pump and not a China build pump. I installed the new pump and have the same readings of 7.5 lbs of pressure.
I then thought to experiment and purchased a replacement "Spectra Premium" 40482 pump. Again, this has the correct long tube inlet shaft but of course no "AC" logo. The box did indicate the pump was made in China. The Spectra pump pegged my snap-on gauge at 10 lbs and gas was coming out of everywhere on my newly rebuilt 3811.
Everyone has been advising me to install a fuel pressure regulator and be done but we all know how they look and I don't want to ruin the "original" look of the engine compartment.
And yes, I did try a different pressure gauge with the same results. I welcome your advice, thoughts or ideas.
Thanks---Stan
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