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Too much fuel pressure?

Mercury MerCruiser

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Old 08-08-2011, 02:23 PM   #1

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Default Too much fuel pressure?

Hey guys,
Has anybody ever heard of too much fuel pressure from a mechanical pump on a carbed motor?
93 Z2350...big block...14 psi at 2200 rpm.
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  • Old 08-08-2011, 06:22 PM   #2

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    Default Re: Too much fuel pressure?

    14psi from a mechanical pump on a big block?? Wow is all I can say. If I remember right big blocks with carbs should have between 5-7psi at wide open throttle. Volume is much more important here than high fuel pressures on big blocks with carbs. 14 psi would be approaching the low end of the pressure spectrum for a fuel injected motor. Only explanation I can think of is a bad fuel pressure gauge or the wrong fuel pump.

    Happy Boating
    Dan
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    Old 08-08-2011, 07:08 PM   #3

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    Default Re: Too much fuel pressure?

    Original pump....I put the gauge in line just to find out.
    Fuel was getting by the needle and seat, had carb re-built. Found out they are a discontinued item, so instead of waiting, I bought a new carb...same model, now I will have a spare. New carb same problem...
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    Old 08-08-2011, 07:33 PM   #4

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    Default Re: Too much fuel pressure?

    I assume that things were working fine then one day the motor started flooding? I am not completely familiar with your engine, but is it possible the motor has a fuel pressure regulator or a fuel return line that is not working properly? Just guessing right now though, will have to do a little digging on this one.
    Happy Boating
    Dan
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    Old 08-08-2011, 07:46 PM   #5

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    Default Re: Too much fuel pressure?

    Oh it HAS to be the fuel pump, I was just curious if anybody else has had this problem. Usually when pumps fail, they don't pump enough or any at all.
    This was a very strange deal to me.......just wonderin'
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