Gas Cap Problems - Team Camaro Tech
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post #1 of 5 (permalink) Old Aug 21st, 00, 04:42 AM Thread Starter
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Join Date: Sep 1999
Location: Abingdon, VA
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I was wondering if anyone could help me with a problem I am having on my 69 Z-28? My car is an early made car (Oct) and everytime I put gas in the car the vacuum on the gas cap is unbelievable. It sounds like it is going to suck the gas tank together. I have replaced the cap with two different ones that are vented but it doesn't seem to make any difference. Any suggestions? Thanks.
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post #2 of 5 (permalink) Old Aug 21st, 00, 07:28 PM
David Pozzi
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Location: Central California, USA
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It should be pressure not vaccum. There is a pressure relief valve in the cap.
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post #3 of 5 (permalink) Old Aug 22nd, 00, 03:15 AM Thread Starter
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It may be pressure but I figured since I have replaced the cap with a new one the pressure would not be there now. Sometimes there is a lot of pressure should it be that way? One guy suggested that I drill a small hole in the gas cap but that sounded dangerous to me in case the gas leaked out. How much pressure should there be on the cap?
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post #4 of 5 (permalink) Old Aug 22nd, 00, 05:24 AM
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Join Date: Apr 1999
Location: Fortuna, CA
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Mine builds up some pressure, more when it's hot out. When the tank is full and I get on it a bit some gas will spill out. This leads me to think my cap is vented. I always thought the pressure was normal but since I found out about the spillage it has me woundering.....

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post #5 of 5 (permalink) Old Aug 22nd, 00, 06:53 AM
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I have drilled 2 holes in my cap but have yet to try it out. If you take you cap off and apart you can see 2 channels in the metal used for escaping pressure. I drilled a hole on the iner most side of each one, but the strange thing is if I put the air compressor to it it flows great at low psi. I put a little light oil on the valve as well to see if it would free it up a little and help the diaphram move easier. David has also mentioned fuel boiling which is what I think is wrong with the muffler placement, but not sure what to do to fix without major cost.

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