1968 Impala Fuel System - Impala Tech
Troubleshooting Diagnosing problems

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post #1 of 2 (permalink) Old 02-29-2016, 04:13 PM Thread Starter
Join Date: Feb 2016
Location: Las Vegas
Posts: 2
1968 Impala Fuel System

Not getting fuel to the carburetor, disconnected the line running from the mechanical pump to the carb and its just pushing out air no fuel. Got Under the car to check my fuel lines connecting to the tank and there were 3 nipples coming off the tank but only 2 had lines on them? the left line was going to the vent in the wheel house, middle was going to fuel line on the frame up to the pump, and the right had no line connected. Is something supposed to go to this? if not what could be causing no fuel to get to carb? line clogged? pump clogged?

TLDR: no fuel to carb, fuel line from tank to mechanical pump is connected.
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post #2 of 2 (permalink) Old 02-29-2016, 04:51 PM
Join Date: Jan 2006
Posts: 12,458
The line going no where is a vent. It has to be open (in Florida Mud Dauber Wasps love to fill all open tubes with stunned but alive spiders for their grubs to enjoy eating as they grow, and then seal the end with spit and sand or mud). So you can not assume it is still open without checking.

The line going to the fuel pump should be 5/16th inch in size if the motor was rated at less than 300 horsepower and 3/8th inch in diameter if a 300 horse or larger motor. It is made of mild steel that rusts (as is your tank) and the rubber hoses that connect the hard lines are NOT compatible with gasohol. Alcohol will cause them to dissolve and leak. They have to be replaced with blue Teflon line neoprene fuel line (green stripe).

Your carb may also be an issue as Rochester QuadraJets have a welch plug in the bottom of the fuel bowl that can work itself loose and ;leak too much gas into the engine when running. The fix is to tap the hole and to put in a pipe plug sealed with epoxy. Alcohol will not be kind to your carburetors finish or gaskets either as it was designed and built decades before Jimmy Carter first dreamed up gasohol as a solution to the gas shortage on 1973 (first OPEC boycott).

If the diaphragm in the fuel pump is ruptured it will not suck gas out of the tank is another possibility. But most likely it is a clogged line or in line filter.

Big Dave
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