vented gas cap
- Thread starter kelly
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answered your own question, nice.. :headbang:
mopar 3 B
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Could have just waited till the tank was sucked flat and asked us what caused it.
GetX'd
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How about an add on dumber question....? How do you know if your gas tank or cap is vented? I've had my car so long and the cap is not nos I have no idea. Just restored and new lines put in. Cap has been on for over 40 years. Sorry but no mechanic in this head...
440roadrunner
Well-Known Member
Start with "what are we working on?"
"I thought I knew" that Mopars used UNvented caps
I don't know about the earlier cars. 67 A bodies was vented via a tube welded into the fender mounted filler tube. The cap is simple. you can tell by looking it is not vented.
The service manuals usually have a layout of "how the tank" is plumbed, and you can usually tell from that
70 CA cars, and all cars 71 / later were vented by the "carbon can" evap control system. The cap was then changed to what was known as "pressure vacuum" to relieve build up pressure. It is NOT an operationally vented cap.
lewtot184
Well-Known Member
take the gas cap off and look at the filler tube. if it has a small groove where the cap seals then it will use a non vented cap. my '65 coronet uses a non vented cap.
Here's my 63 Fury set-up. Like Doug said, the filler neck should have a notch (right side at 3:00 position on picture) that vents the tank. Easiest way is to buy one from NAPA or rockauto.com for YOUR car.
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mopar 3 B
Well-Known Member
The venting is just as much for letting air in as letting pressure out.
kelly
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Not sure what to think about vented or no vented gas caps. I had a non locking on and then went to a vented type. The car has clear gas filters so I can see the gas in them. It ran out of gas on the top filter (after the fuel pump) would not start. The filter before the pump was full. I put the locking back on and it starts and idles fine,
what the #%#@@% is that all about.
65hemi
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Kelly, after the car has been running for a while go remove the gas cap. If you hear air rushing or hissing into the tank, you need a vented cap.
440roadrunner
Well-Known Member
Maybe, maybe not. MAYBE there is something wrong with the vent system. I try to discourage using vented caps instead of fixing "some other" problem. On cars with a fender mount gas cap, using a vented cap when the vent is actually at fault is an excellent way to get fuel all over the side of your car
"Back in the day" I could have just grabbed a Gates / Stant/ other catalog and looked up the application. Now, those catalogs generally don't exist, and the internet world of O'Reallys and NAPA are often incorrect or ambiguous
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