New Gas Cap has me confused? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Beach-Burban · 11-05-2023, 02:41 PM

Recently installed Edelbrock Pro Flo 4 EFI and Fuel Sump Pump to my ‘72 Suburban, which calls for a vented fuel system. I removed the charcoal canister and utilized the factory vent line that went to it (as suggested by Edelbrock) and replaced the factory “Vacuum Pressure” gas cap with a “Vented” cap…but there is still a noticeable “whoosh” sound when I remove the cap after driving it? Am I overlooking something? Any advice would be appreciated.

Woody

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**71CHEVYSHORTBED402** · 11-05-2023, 03:04 PM

My 72 did that once or twice, with a new cap. I replaced it with one of these. Same was on my 71 with the vapor can removed.

What does Edelbrock say to do with the vent line?

Beach-Burban · 11-05-2023, 08:47 PM

Quote:

Originally Posted by 71CHEVYSHORTBED402

My 72 did that once or twice, with a new cap. I replaced it with one of these. Same was on my 71 with the vapor can removed.

What does Edelbrock say to do with the vent line?

Thanks for the response, Tony…this never happen when the canister was hooked up (even when using the factory “Vacuum Pressure” cap?), but it was a QJet then. Edelbrock said to run the vent hose from their Fuel Sump Pump directly to the hardline that the canister used to run to (located down on the frame, close to the radiator). They call it a “vent”, and specifically say that a “return” is not required.

Woody

11-05-2023, 02:41 PM	#1
Beach-Burban Registered User Join Date: Mar 2019 Location: So. Torrance, CA Posts: 469	New Gas Cap has me confused? Recently installed Edelbrock Pro Flo 4 EFI and Fuel Sump Pump to my ‘72 Suburban, which calls for a vented fuel system. I removed the charcoal canister and utilized the factory vent line that went to it (as suggested by Edelbrock) and replaced the factory “Vacuum Pressure” gas cap with a “Vented” cap…but there is still a noticeable “whoosh” sound when I remove the cap after driving it? Am I overlooking something? Any advice would be appreciated. Woody

11-05-2023, 03:04 PM	#2
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,186	Re: New Gas Cap has me confused? My 72 did that once or twice, with a new cap. I replaced it with one of these. Same was on my 71 with the vapor can removed. What does Edelbrock say to do with the vent line? Attached Images __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring the truck from ground up. With assys, the guide accts for 1000s details, OEM identifications & part numbers, written in short order. 700+ images of assm., illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025



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