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Discussion Starter #1
I am running a holley mechanical 130gph fuel pump. It says that it does not require a regulator. When the car is idling the fuel pressure guage fluctuates very rapidly between 4-7 psi. The needle moves back and forth very quickly. Does anyone know what could be causing this? The car seems to idle fine although I do have a slight miss that I am trying to figure out.
 

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If it is actually the preasure fluctuating it might be an air leak on the intake side of the pump. I'd imagine a leak on the output would of already been spotted. Some place along the line a switcharo has happened with the fuel and return line of the tank and from what I've heard the car will still run but runs bad with that set up. What I'd suspect is actually going on is the pump is reading every squirt of a diaphram pump. Is it electric or a cam driven pump?
 

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The fuel pressure gauge is it a fluid filled unit (more expensive type). I installed a non fluid filled fuel pressure gauge at the same time I upgraded to a electric fuel pump and new fuel line. The gauge would bounce around wildly from 3 to 9 psi. I knew the fuel pressure was non changing (fuel pressure regulator), So replaced with a fluid filled unit now it stays steady at 7-psi.
 

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Discussion Starter #4
Its not a fluid filled one. Its a cheapo one that came with the fuel line in a kit. I'll upgrade the gauge to rule that out.
Thanks,
Greg
 

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Hey GregD

I had the same problem with a cheap gage. It drove me crazy. I changed the reg same problem. I installed a BG gage cleared everything up.
 

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You can place a snubber in the gauge port. Just need something with a tiny hole (30 thou) in it to dampen the pulsing.

The better gauges have a piece that threads into the port on the gauge itself. Problem is that sometimes they fall out. I've had them jam the regulator open.

Bob.
 

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Discussion Starter #7
I ended up getting a liquid filled gauge and it solved the problem. Thanks guys!!
 
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