Vented or Sealed gas cap
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Supreme Member
Joined: Oct 2001
Posts: 8,113
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From: NWOhioToledoArea
Car: 86-FireBird
Engine: -MPFI
Transmission: T5
Axle/Gears: 3:42
Vented or Sealed gas cap
Vented or Sealed gas cap, does it really mattter cept to the EPA?
I want one of the caps with a flap in so you can fill up without taking it off.
I want one of the caps with a flap in so you can fill up without taking it off.
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Joined: Jan 2000
Posts: 20,981
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Vented or Sealed gas cap
It probably doesn't matter except to the EPA, as long as there's some kind of venting for the tank.
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Joined: Nov 2002
Posts: 1,832
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From: Castaic, CA
Car: 1988 Camaro RS
Engine: 2.8L of Raw POWER!!!
Transmission: Stick Shift
Axle/Gears: 3.42's
Re: Vented or Sealed gas cap
In my experience, the ones with the flip top are typically worse to have because they tend to not seal right and leak out the fumes on hot days...resulting in what looks to be poor milage.
about 31% of people who complain of poor milage can attribute their problem to an undermaintained EVAP system, which includes the fuel cap and EVAP hoses. The fuel actually evaporates right out the hole. A hole 0.020" in diameter can cause a lose of aprox. 1 gallon of fuel per month.
In California we're actually going to be testing the evap system of all vehicle between 1976 and 1995 for EVAP problems using a special tester starting on Nov. 1st as part of the smog inspection.
about 31% of people who complain of poor milage can attribute their problem to an undermaintained EVAP system, which includes the fuel cap and EVAP hoses. The fuel actually evaporates right out the hole. A hole 0.020" in diameter can cause a lose of aprox. 1 gallon of fuel per month.
In California we're actually going to be testing the evap system of all vehicle between 1976 and 1995 for EVAP problems using a special tester starting on Nov. 1st as part of the smog inspection.
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Joined: Oct 2006
Posts: 558
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From: Pittsburgh, PA
Car: 1992 Pontiac Firebird
Engine: 3.1
Transmission: 700R4
Axle/Gears: 3.42 Auburn Posi
Re: Vented or Sealed gas cap
That's good to know! I think I'm going to check the rubber lines of my EVAP system, as I think some are dryrotted.
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