>>> new pump not working no suction <<< please read

[1BAD65]

1972 C10 350CI V8 - QUADRAJET CARB - MECH. FUEL PUMP - FULLY STOCK

I need to clarify a few things.

I just searched several "New Fuel Pump No suction" threads here and I am having the same issue.

Question #1

First let me ask this question as I stumbled upon a thread that stated:

"THE SENDING UNIT LOCATED IN THE FUEL TANK SENDS FUEL TO THE FUEL PUMP WHEN THE IGNITION SWITCH IS TURNED ON"

wtf????

I never heard of this? I understand its call a "Sending Unit" but that is because it tells the fuel gauge on the dash how much gas is in the fuel tank and that is all. Right???

I know there is pickup tube along with it as well.

Question #2

Does a NEW mechanical fuel pump require PRIMING after being installed?

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Here are the things I have tried:

Replaced fuel pump twice

Made sure push rod was free and also used white grease to hold push rod in place so it would not slide down behind lever while installing new fuel pump.

Used a short piece of fuel line attached to "IN" port and placed the other end in a bottle filled with gasoline- cranked the engine - no suction - the fuel pump would not suck any gas from the bottle which was inches away from the new fuel pump.

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all rubber lines replaced in the fuel line system.

dropped the fuel tank and cleaned out all debris and sediment

blew compressed air through the fuel line that connects to the fuel pump and when I did that allot of gasoline poured out from top of the tank.

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New Plan to Solve this Problem

prime carb with gasoline and crank the engine

reverse both fuel lines on top of fuel tank- maybe they are connected incorrectly

prime carb again - crank engine

if it still does not start then :

I will install a new mechanical fuel pump again for the 3rd time and repeat the priming process


GUYS, LET ME KNOW IF I AM MISSING ANYTHING

THIS A FUEL PROBLEM - I HAVE SPARK AND COMPRESSION

TRUCK LAST RAN FINE ON FRIDAY TODAY IS NOW WEDNESDAY

THANKS FOR ALL OF YOUR HELP