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85 "Starship" Berlinetta gas tank pressure

Old 08-14-2015, 06:06 PM
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85 "Starship" Berlinetta gas tank pressure

So I just recently bought the good ol Starship camaro 2.8l v6. Ran great at first but then started to notice her idle a little less easy (almost struggling) and the smell of gas was more prevalent.

Decided to fill her up not sure whether I was low on gas seeing how most of the gauges malfunction. That's when I heard the hiss after I opened the tank up. Figured it was running on fumes till I decided to check for the woosh sound again later that day, same thing happened. Felt like it was blowing out pressure instead of sucking in.

Any ideas? I was looking at replacing the iacs or the charcoal cannister filter. Am I on the right track or is there more I should be looking into.

I'm new to these third gens and, in general, cars all together so go easy on me...decided to make this a restorarion project.
Old 08-14-2015, 07:12 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

This is one of the problems with these cars that we can't quite get a definite answer on. The evap canister could be the issue but I don't think changing the filter would help much. There's a white tank breather coming down by the driver side back seat floor pan but there's no way to get a brand new one anymore, I have the pressure issue as well and am tempted to take a good hard look at that breather
Old 08-14-2015, 07:18 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

I'll have to take a look at that as well. Going to a garage tomorrow to take a better peak. Thanks for the suggestion. I'll be sure to update as I progress.
Old 08-14-2015, 07:49 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

The gas tank is SUPPOSED to hold some pressure. That's how these cars were built. There is a tank vent like TylerSteez said. It's designed to hold about 1PSI of pressure before it vents to atmospere. It should open under ANY vacuum. It's basically a spring-loaded vent like you would normally find in the gas cap, but on 3rd gens the gas cap is a solid plug and the venting duties hare handed by this separate unit down by the gas tank.
Old 08-14-2015, 07:58 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

Oh ok. That solves that. But I am still curious though why I still get an idle that struggles and the smell of gas while idling only. I thought the whole gas tank pressure might have been a part of the problem, but seeing how it's not I have nothing on where to go with these issues other than getting a new IACS.
Old 08-15-2015, 11:26 AM
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Re: 85 "Starship" Berlinetta gas tank pressure

Thanks for explaining that Damon, good info.
Old 08-15-2015, 01:36 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

So the problems listed above have almost taken care of themselves. I assume it was the fuel system cleaning additive I put in the tank the other day. Only concerned because I've never had a car do that to me after adding in said cleaning agents. Picked up a Chilton repair manual today, heard people swear by them.

Thanks for the useful info guys.
Old 08-16-2015, 08:04 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

Originally Posted by BurlyChev
Picked up a Chilton repair manual today, heard people swear by them.
No, maybe swear at them. Factory Service Manual (FSM), yes, go by them.

RBob.
Old 08-16-2015, 09:08 PM
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Re: 85 "Starship" Berlinetta gas tank pressure

Alrighty then, I'll get that as well. Thanks for the heads up, bob.
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