An empty gas filter...but car still runs? - Team Camaro Tech
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post #1 of 11 (permalink) Old May 1st, 03, 02:41 PM Thread Starter
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Hey guy's, Very strange happenings going on under my hood.... Today I noticed (while the motor was running) that I had no gas in the see through gas filter. I drove the car hard for about an hour before this and the car ran great.
I shut the motor down and about 10 minuts later the filter was filling up with fuel, once it filled up about 3/4 of the way I could see air bubbling (comming up through the fuel pump line).
I took off the filler cap on the gas tank and it hissed at me, so I went back to see if the bubbling stoped and it bubbled even quicker.
I started the car and the carb sucked the gas out the filter...but the motor stayed running. I even drove it 10 miles back to my house without a problem...
Do you think my fuel pump is on it's way out?
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post #2 of 11 (permalink) Old May 2nd, 03, 12:43 AM
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I have heard of this, its the fuel evaporating causing the air pockets at the highest points.

If the filter is horizontal, air will got to the top and fuel on the bottom. If the filter is vertical, fuel will fill up from the bottom, thus displacing the air as it fills. Then, as the fuel evaps when hot, it will vent at the carb and out its vent.

I would like to read of others opinions......

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post #3 of 11 (permalink) Old May 3rd, 03, 05:09 PM
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I agree with Everett; I hope you don't have one of those glass or plastic in-line filters cut into the steel line with rubber hose and clamps - it may look cool, but it's a fire hazard [img]graemlins/clonk.gif[/img]

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post #4 of 11 (permalink) Old May 4th, 03, 01:05 PM Thread Starter
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I put a glass see through filter on it cause I had a feeling my gas tank was full of crud.
I put a new tank and sending unit in the car and I kept the filter in for the time being.
I will try to reposition the filter to see if that works.
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post #5 of 11 (permalink) Old May 7th, 03, 08:14 PM
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That's what you call "running on fumes!!!" Better filler up!! [img]tongue.gif[/img]

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post #6 of 11 (permalink) Old May 9th, 03, 08:05 AM
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My Chevelle has run that way for years... I always thought it was strange also! Mine in mounted vertically in the line coming up from the pump, but before the regulator. I've got one of the clear plastic filters so that shouldn't be a hazard right? Anyway, the gas is always just bubbling right at the bottom, but the carb always stays full and the car drives fine!

FYI, I have the same filter mounted in the line AFTER the regulator and horizontal in my Nova and the filter is always full!

Go figure!
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post #7 of 11 (permalink) Old May 10th, 03, 03:10 PM
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Go figure, I thought I was seeing this or going to have problems as well. My plastic inline filter mouted up and down between the mech. pump and the carb does this as well. But sometimes it is completely full, sometimes only about 1/3 full. I can buzz it to 6800 and doen't run out of fuel. - Barry
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post #8 of 11 (permalink) Old May 11th, 03, 04:09 AM
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I just had the same problem the other day but, with my car, I only had to put the gas cap on the right way. Down here everything is full serve and the punk kid didn't put it back on correctly. That's when I noticed that my vertically hung clear glass filter wasn't filling up but the car still ran. Have you ever replaced the gas cap?
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post #9 of 11 (permalink) Old May 11th, 03, 08:41 AM Thread Starter
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Hey Judd,
The tank came with a new cap...I thinking I should get a vented gas cap to keep it from hissing everytime I get gas.
My first thought was "my fuel pumps not working!...but wait, how is the car running?"
It seems like I'm not the only one with this filter problem.
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post #10 of 11 (permalink) Old May 24th, 03, 08:09 PM
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Well, sometimes you do get to see that other's go through the same trauma as you do. I just noticed the exact same thing on my son's 1973 Z-28 the other day whilst working on it. Sometimes the filter stays full and other times it will run at 1/3 or even look empty with just a few bubbles visible as the motor is running. I have driven with it like this no problem. I have revved the motor up quite high and even though you don't see any large amounts of gas passing through the filter the vehicle still seems to be running just fine....go figure... ? As with the rest of you all (i'm sure) I will be watching this spot to see if there's any explanations for this phenomena....
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post #11 of 11 (permalink) Old May 25th, 03, 02:35 AM
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To clarify, its not air getting in your fuel system; its gasoline vapor. Mine does the same since the fuel line runs very close (~ 1/4") to the headers and it will bubble thru the gas filter. Generally does it more so when idling since the fuel is not being used up as fast.

I haven't worried about it too much but I'm sure its wasting gasoline since its just vented out the carburetor.


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