95SLS Posted June 17, 2004 Report Share Posted June 17, 2004 Not my car, but my car don't do this and hers does. When just sitting idle, you start up and after 20 seconds you hear a hissing noise that sounds like an air leak, I pulled it on a cement pad and rolled around, put ear on fuel tank and that is where it comes from, only does it when the car is running, not when the key is just on. Almost like it builds up pressure and then releses it somewhere into the tank. OR the pump backfeeds, whatever. It's a hissing noise from the tank. I thought sure it was an air bag leak. Car rus fine. But wondering about it. MC Link to comment Share on other sites More sharing options...
95SLS Posted June 17, 2004 Author Report Share Posted June 17, 2004 Be nice if I told ya it was an Eldorado y with a 4.6 1996 model. MC Link to comment Share on other sites More sharing options...
Randy_W Posted June 17, 2004 Report Share Posted June 17, 2004 Sounds like you need a new gas cap. Link to comment Share on other sites More sharing options...
Ranger Posted June 17, 2004 Report Share Posted June 17, 2004 Are you sure it's "pressure" and not vacuum? As the tank is emptied the fuel used must be replaced with air thru the cap or the pump will be unable to draw fuel or it will collapse the tank. Sounds like maybe your cap is not venting properly. Link to comment Share on other sites More sharing options...
95SLS Posted June 17, 2004 Author Report Share Posted June 17, 2004 Ok guys, will switch out the cap with my caddy and try that. I should have thunk of it! Doink! I'll post results. Mike Link to comment Share on other sites More sharing options...
95SLS Posted June 18, 2004 Author Report Share Posted June 18, 2004 Alright switched caps, still noise BUT it quits when I loosen the cap. So I am going to buy a new one, Be posting back. MC Link to comment Share on other sites More sharing options...
95SLS Posted June 18, 2004 Author Report Share Posted June 18, 2004 Maybe I was chasing two problems. I bought a new cap put it on and seemed like the tank part lowered quite a but not going away. Very liveable though, Who drives with their head under the car? Then after I get that changed I do still hear a hissing noise when the air compressor kicks on, Almost like it is pumping into somethin with a hole in it. Just of the AC I notice on top a line out and a T the line about 3 inches long that T'ed off the top of the AC was rotten. As in totaly un-connected. I put on some new line and it still does it when it runs but it don't do it all the time. Have no Idea what this goes to, just some part on the frame, looks like a sensor or something. Anyhow, That's my go over, it better be right as I am going to put it to the test on a Vacation trip to Canada. Towing a boat. MC Link to comment Share on other sites More sharing options...
KHE Posted June 18, 2004 Report Share Posted June 18, 2004 Didn't you post earlier that the car was riding low in the back? I'd check the air lines to the rear struts - particularly where they get close to moving suspension parts. If you find a chafed line, GM sells a repair splice - about $2.00 at the dealer. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
95SLS Posted June 28, 2004 Author Report Share Posted June 28, 2004 I must have a leak like you say in an air line, cause it rode low all the way there and back and I can hear it but I can;'t locate it. I found on line totally missing and rotted, but I have yet to find the other leak. Only leaks with weigh on it and car running. MC Link to comment Share on other sites More sharing options...
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