71 super B. carb is good. cleaned gas tank. replaced fuel filters. replaced fuel pump. engine idles forever, but drives great for 15 min. then doesn't get any gas. I have to pull gas line from tank side of fuel filter in engine, blow and siphon till I get gas. Why won't gas continue to flow?

Check that the tank's vent is open, could be that running the engine is causing a vacuum in the tank up to the point where the pump can't pull any more fuel. When this happens you can usually hear it sucking in air when you remove the gas cap.

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Rowen,

Welcome.

Has the gas tank been removed and reinstalled recently :?: Another possible problem could be that the fuel line, that is attached at the fuel tank, could possibly have a crimp in it somewhere at or near the tank. That portion of the line may be crimped just enough to prevent the normal flow of gas from getting to the motor.

When you get the problem solved please be sure to let us know what it was and what you did to solve it. I/we want to know.

Larry 🙂

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Yes, the tank was removed for cleaning. I'll recheck to make sure nothing is crimped. What does the separator do? Do I need it? I'm pretty sure the evaporative system has been modified or plugged. Will I need to rebuild it to original operating standard? Some of the vent lines are cracked at the ends. Should they be replaced? The bug is in Texas where unfortunatly there's not much worry about the environment (thanks to W.)

Rowen,

It is quite possible that you may have a crimped fuel line on your hands, easy fix. This is what I was told about removing and especially reinstalling a gas tank. Keep the fuel line from the gas tank as SHORT as possible.

Someone that I know had the exact same problem, early 70's car would quite running, just a few weeks ago. When it was mentioned that he had removed the gas tank and then decided that it would be easier to reinstall it using a longer piece of tubing. You know, he attached a new piece of tube to the tank and the connector and THEN placed the tank back into position. Of course it went in the car much easier that way but the extra length of line crimped, cutting off the normal flow of gas. The tube was then cut to the proper length and problem solved.

I have to admit I have no idea what a separator is so I cannot answer that part of your question. Can someone assist Rowen with that question?

Larry

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