fuel pump question

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HotRodPC

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So it was necessarily a vapor return to the tank, but fuel return to the tank.
 

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I don't write it, I just present it.

I would suppose that any fuel delivered that the carb can't handle would be pumped back to the tank. That's my best guess. Why? I don't know. How did they work without it before the smog junk?

I always figured they pumped to a certain pressure and then there was a relief valve that prevented any 'backlog'? of fuel.
 

Blue Ox

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If the pressure gets too high the spring can't push the diaphragm until the pressure drops. So basically they just stop pumping and the lever just moves around unloaded.
 

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So you're sayin' that the spring is calibrated for a certain pressure against the diaphram and when that pressure is reached it doesn't move the diaphram anymore.
 

Blue Ox

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Yep.
 

HotRodPC

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Looks like I was wrong. Nice to learn tho.
I don't know what your guess was, but I was almost right but not. Hang out a bit, you'll learn lots. I get corrected on here plenty. It's the guys that WON'T BE or CAN'T BE corrected that tend to get butt hurt and run off, and so be it.
 

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Hey, I got the pic off the internet so you know it has to be true. But I trust this one.
 

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