Air bubbling into the fuel filter

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Ewhitaker0020

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On my 1980 C30 truck I notice that there's mostly air being pumped from the fuel pump into the plastic fuel filter just before the carb.

When I say air I mean a lot of air. I can barely see any fuel making it into the filter. Even when I turn the fuel filter on its end so the fuel he to enter from the top there's barely at fuel making it through. But, I know there is fuel because the truck is running and the filter stays roughly half full of gas. The truck runs fine. It idles like a champ. There's a little backfiring when driving, but not much.

After doing a quick Google it seems like I probably have pinhole leaks in a fuel line somewhere and they're drawing in air? What is your take on this problem? I can replace the rubber lines, that's no problem. If that's what I need to do.

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AuroraGirl

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first, your filter is junk. get a nice metal screen one.
( i can say this because mine literally pulled itself in on itself from being cheap and degrading from ethanol free fuel)

second, replace rubber lines in all sections, if you havent done it its probably due for them.

if problem persists(not observable, so...) then clean lines and clean your tank/sender or replace. if problem persists pump. if you dont have leaks and you put new filter/line in, dont worry about it.
 

Ewhitaker0020

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first, your filter is junk. get a nice metal screen one.
( i can say this because mine literally pulled itself in on itself from being cheap and degrading from ethanol free fuel)

second, replace rubber lines in all sections, if you havent done it its probably due for them.

if problem persists(not observable, so...) then clean lines and clean your tank/sender or replace. if problem persists pump. if you dont have leaks and you put new filter/line in, dont worry about it.
I want to stick with a clear filter so I can see how dirty my fuel or tank are. On my truck I have a glass one, but my father in law didn't want to spend that much money on one. I guess we'll go ahead and replace all the rubber lines. I'm sure they're probably original.

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AuroraGirl

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whats the condition of this plastic filter then.
i have some pretty sketch ones on my buick, lines that is. definitely make sure fuel hose goes on.
 

Curt

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Is it possible that there is a small hole in the diaphragm on the fuel pump?

Of course I’d look at fuel line first
 

AuroraGirl

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I want to stick with a clear filter so I can see how dirty my fuel or tank are. On my truck I have a glass one, but my father in law didn't want to spend that much money on one. I guess we'll go ahead and replace all the rubber lines. I'm sure they're probably original.

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i sounded rude about the filter, i meant to be asking what is its physical condition. warped? Full of crud? New? COllapsed? bulged?
 

Grit dog

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You most likely have an air leak between the tank pickup and the fuel pump.
Any fuel leak when the engine is off? Could be where the bad line is.
No air when the tank is full = hole in the pickup in the tank.
 

75gmck25

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Over the years several of my rubber fuel lines developed significant cracks, and in a few cases started to leak. It might just be age, but the new fuel with ethanol probably accelerated the deterioration.

if possible, use new line that meets the SAE J30R7 (low pressure) or SAE J30R9 (high pressure) specs for EFI fuel hose. It should hold up much better when you have ethanol in the fuel.

Bruce
 

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