LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Correct Fuel Pressure

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Old 07-21-2003, 12:35 PM
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Location: flomaton, alabama, USA
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Correct Fuel Pressure

I talked with John who works with Ed Wright and he says my high rpm miss is probably due to low fuel pressure. John says I should be holding about 46-48 pounds of pressure at wot. My stock pump won't hold that much pressure, it only holds 42-44 lbs(vacuum line disconnected) at WOT, I restricted the return line and it went to 70 lbs but when I make a wide open pass it still drops back to 42-44 pounds. I have never heard anyone say to run this high of fuel pressure, what do you guys think I should be running. John thinks I need an afpr, or a new pump if so what brands do you recommend. thanks
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Old 07-21-2003, 12:45 PM
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I have a Hypertech fuel pressure regulator set to 47 pounds. Ed Wright did my tuning. He recommended the pressure. The stock pump should he enough nads to keep up with 47 pounds.

You want to make sure you have enough flow in addition to the pressure. A clogged filter can make you too lean even if you have too much pressure.
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Old 07-21-2003, 02:13 PM
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Your FP is holding what it should. The stock GM injectors are rated at either 43 or 43.5psi, which is what you should be running at WOT. You're right where you should be.
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Old 07-21-2003, 02:58 PM
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fuel pressure

Thats what I thought also but Ed Wright is the guru for tuning and if he says go to 46-48 he probably has a reason for it. I am just wondering if the test I did by restricting the return line out of the regulator to boost the pressure up is an accurate way to see if the fuel pump is performing up to par. It seems to me if it were putting out 70lbs restricted and I go to wide open throttle it should maintain 70lbs, but it doesn't it drops back to 42-44lbs and when I let off the throttle it goes back up to 70lbs. Isn't this what a adjustable fuel pressure regulator does, restrict the return line to boost inlet pressure? And if so the fuel pump should be able to maintain that pressure if operating up to par and if it doesn't it is bad not the regulator. Correct me if I am wrong, PLEASE
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