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Subject:Re: Fuel Pressure
From:George Goff
Date:Thu, 9 Jun 2005 07:50:06 EDT

In a message dated 6/9/05 12:53:36 AM, maxjoyce@IPA.NET writes:

<< Starts off like the specs say it should, but gradually the max pressure is
around 28 and  decell(high vacuum) low 20's.  Could this be grunge in the
intake coming from the tank . . . >>

Max,

I imagine you are using the fuel supply pressure test point to take your
measurements and the fuel pressure regulator appears to be working as it should,
although at a lower system pressure once hot.  If so, I would next test the
output pressure of the fuel pump, both cold and hot, with the pump dead-headed to
a pressure gauge.  Take adequate precautions with your test setup because a
healthy fuel pump will produce a much higher pressure when dead-headed.

I doubt if some crud would affect the output pressure of the pump as much as
restrict the flow.  Still, if you do a pressure check, you should certainly
test the rate of flow both cold and hot.  The proper rate of flow is probably
noted in the Bentley, but, for your purposes, all you really have to look for is
a markedly different rate between the cold and hot measurements.

Being electrical, the motor of the fuel pump might be suffering some drag
once it heats from running under load.

George