Small gas leak during cold start - Chevelle Tech
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post #1 of 6 (permalink) Old Sep 22nd, 15, 2:11 AM Thread Starter
 
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Small gas leak during cold start

If I let my '72 Malibu sit for a week or so and then try and start it I end up backing out of my garage and finding a small puddle of gas on my garage floor directly under where the fuel pump was. I just replaced the fuel pump a few months ago so I seriously doubt that it would be the rubber diaphragm that is faulty. I don't know what would cause a spurt of gas only when I start it for the first time in over a week but then subsequent starts won't have the same result. I do have to sit there and crank it for a little bit on the first start, but I can't seem to figure out what the issue is.

Please give me any thoughts on what the issue is. Thanks!
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post #2 of 6 (permalink) Old Sep 22nd, 15, 9:18 AM
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Flarenut at carburetor fuel line Re: Small gas leak during cold start

My stock 71 2GV would self loosen the big gland nut that holds the miniature paper fuel filter at the front of the carb (Rochester 2GV) I think maybe because tightening the flare nut on the fuel line there would slightly wind up the metal fuel line. Then, time, vibration and thermal cycling would have it loosening the gland nut. Solution was to make a tool to clamp the fuel line. So, first tighten the gland nut. Then, while torqueing the fuel line counterclockwise slightly, tighten the flare nut.

Tool is a block of aluminium. Drill a 3/8 hole through it. Saw the block in half so that the hole looks like two "half-pipes." (Tool is expected to also be useful for loosening of flare nuts that want to turn the line with them.)
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post #3 of 6 (permalink) Old Sep 22nd, 15, 11:08 AM
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Re: Small gas leak during cold start

Before you start it feel around where the 2 lines hook to the fuel pump and see if your finger come out with gas on it. Check the metal line going to the pump sometimes you think it's tight but you have to give it a little more to seat the flare of the line.
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post #4 of 6 (permalink) Old Sep 22nd, 15, 11:59 AM
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Re: Small gas leak during cold start

As suggested above it is probably the metal line leaking at one end. It may seep all the time but evaporate quickly. Once the fuel in the line all drips out the ground will be dry. You notice it when it starts because the line is refilled and the puddle is fresh.

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post #5 of 6 (permalink) Old Sep 23rd, 15, 11:38 PM Thread Starter
 
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Re: Small gas leak during cold start

Well see that's what I thought too, but it doesn't leak every time I start it....it only leaks when I start it after not starting it for a week or more. And when it does, it leaks quite a bit. It's not a small amount by any means. It's almost as if there is an abnormal amount of pressure in the line wherever it's leaking when I start it. I did forget to mention that when I get out and look under my car after I start it, fuel is dripping from the chassis just behind the fuel pump. That makes me think that the metal fuel line is leaking from where it is fed through the chassis. Has anyone ever heard of something like that happening? I don't want to remove the fuel line if I don't have to, but I'm thinking that could be the issue.

Any thoughts?
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post #6 of 6 (permalink) Old Sep 24th, 15, 9:14 AM
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Re: Small gas leak during cold start

Did you have the leakage problem before you changed the pump. Did you replace the rubber line. Is it leaking before you start it or after. Your best bet is to crawl under it and look around and feel around for the leak. I can't see it being the metal feed line running thru the frame because to me it would leak constantly. Does the fuel pump have a small vent hole in the side near the bolts it could be leaking there or even around the diameter of the pump where the metal bottom is rolled over to mount it to the cast part of the pump.
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