BBC stock fuel pump - ridiculous fuel pressure

Discussion in 'High Performance Modifications' started by 450bench, Jan 1, 2020.

  1. 450bench

    450bench Veteran Member

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    just letting anyone know who runs stock fuel pumps, I put a new, stock fuel pump on the old 454 79 z28. Part number AMF 0068. Works great but noticed the car smelling like raw gas and had erratic idle. Plugs were wet too. Tried tweaking the carb, checked the timing etc. No help. Then checked the fuel pressure. It was right at 10 psi. Shocked. Put a new ac delco 40727 pump on. Same exact situation. 9-10 psi. Holley 4779 750 dp didn't like that at all. Put a regulator on it and got it down to 6 psi. Much better and car runs great now.
    Really surprised that a stock pump put out that much pressure. That's just not acceptable.
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    Summit lists this pump as 9 psi. Any Holley carburetors I've had didn't like anything over 7 psi. Most performance type mechanical fuel pumps I've had are in the 9 - 10 psi range also and I had to use a regulator. Looks like Carter has a M6626 that's rated at 5.5 - 6.5 psi. That might be an option for you.
     
  3. 450bench

    450bench Veteran Member

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    That's a small block pump, but I hear ya. I bought an edelbrock 1722. I'll try that.
     
  4. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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  5. BigBlock73

    BigBlock73 Veteran Member Lifetime Gold Member

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    I was recommended by the engine builder to use that Carter pump. Worked well with my Holley.
     
  6. G72Zed

    G72Zed Veteran Member

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    As the old saying goes"you get what you pay for" and when it comes down to mech. fuel pumps, there's a reason why the CARTER brand is recommended in many street, and even more racing applications.
     
  7. berg2695

    berg2695 Veteran Member

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    The factory fuel pressure for late second gen Zs was around 9 or 10 psi. I always wondered why they did that. Maybe tighter control of the fuel level in the carb for emission reasons? I don't know. I regulated it down on my car too.
     
  8. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    And many of these came with a bypass fuel pump too. I don't know what they were regulated at and I still have the return line on mine.
     

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