Fuel Pressure

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B-Co Kid

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351W; C6; Carb'd; no EEC/ECU from factory; all emissions stuff deleted; bored over .60; 

The fuel pressure I get on the gauge just before the carb is sporadic.  When warming up, and at times after the engine has already warmed, the fuel pressure gauge flickers between 6-9 psi, and sometimes closer to 9psi.  Other times, after the engine was warmed, its steady at 6psi.  Is this normal?  Should I be concerned??  I figure a failing fuel pump would decrease or show very little pressure, but in my case its normal to high.  Any help is greatly appreciated..

 

miesk5

96 Bronco 5.0
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Yo B,

Are you  using an electric fuel pump?

Which brand pressure gauge/sender?

Holley states:

Please call Tech Support at 1-866-464-6553, M-F, 8-6 CST. Please have the part number of the product on hand when you call.
Connect the fuel line from the tank to the fuel filter and the filter to the inlet port of the pump. Connect the carburetor feed line to the outlet port of the pump. Use of 3/8” fuel hose is recommended.A #6 (3/8") line size is sufficient for all street performance applications and some racing applications. #8 (1/2") fuel lines are used on everything
else, including alcohol applications. Avoid using rubber fuel lines, or use
them sparingly, for two reasons. First, rubber is more resistant to the flow of
fuel than any hard line. An actual pressure loss can be measured over distance


Carbureted vehicle fuel pump; Most electric fuel pumps, including Holley are gravity fed and require mounting below the fuel tank

"MAINTENANCE AND CLEANING INSTRUCTIONS FOR ELECTRIC FUEL PUMPS:

Due to the current poor quality gasoline that’s available, it is recommended that periodically a can of dry gas be used to absorb the water out of the fuel delivery system. The fuel filter element should be blown clean with compressed air every 6,000 miles and replaced every 12,000 miles to assure maximum protection. If your fuel pump fails to pump or fails to maintain adequate 
pressure, check the following:
1. Check the voltage at the pump to ensure 12-volt supply.
2. If this doesn’t solve the problem, turn the pump on and listen for a hum from the top of the pump. If there is no hum, the pump’s electrical system should be checked by a competent mechanic. If the pump hums, it probably only needs to be 
cleaned.
3. Check the fuel line (especially the fuel filter) for any obstruction. Use compressed air to blow the line free."

 
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B-Co Kid

B-Co Kid

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It's a mechanical fuel pump which is why it doesn't make sense.  The fuel pressure gauge is a mechanical Holley non-liquid filled gauge.  It is installed on a threaded port on the carb inlet fuel line; 

 

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