Gas sucking out of my locking gas cap! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

epashhans · 09-01-2009, 02:10 PM

So when I got the truck it had an older locking cap so I figured it had a leak or something and got a new cap. Now its still doing it! When I drive down the road its coming of the center of the cap and blowing down the side of my box! Has anyone has this before? Doesn't seem to do it when the tank is lower with fuel...but I want to be able to fill it up. Some kind of suction going on? I currently have an electric fuel pump going to a 454 with an edelbrock/carter on it. Anyone have any ideas? I did order a new gasket for the sending unit because it has a small leak...could that be causing it? Thats the next thing I am going to try!

**leddzepp** · 09-01-2009, 02:17 PM

Sounds like you need a vented cap.

epashhans · 09-01-2009, 02:57 PM

Wouldn't it just come out the vented cap as well?

vectorit · 09-01-2009, 03:30 PM

Check the vent tube on the tank, since they tend to get pinched off sometimes against the body.

Ace in the hole · 09-01-2009, 03:59 PM

vented caps do it too, it happened on my 70 all the time with a new vented locking cap.
67-70 do not have a vented tank so you are kind of stuck with a vented cap and I don't think you can get away from some sort of spillage when the tank is full.

Sinister · 09-01-2009, 04:09 PM

Could it be the locking cap? I run a regular vented cap and can fill the gas tank pretty full with no spillage.

epashhans · 09-01-2009, 04:15 PM

Quote:

Originally Posted by vectorit

Check the vent tube on the tank, since they tend to get pinched off sometimes against the body.

Thanks, I will look there too.

westbrookw · 09-01-2009, 05:39 PM

I had something similar with a mechanical pump. It was sending fuel back in the return. I had to replace the mechanical bc it ruptured inside. Maybe the pressure is too high on the mechanical. Not sure.

captain · 09-01-2009, 05:46 PM

I bought a locking cap from LMC and gas would gush out of the keyhole whenever I turned right. It was a piece of garbage.

olyeller70 · 09-01-2009, 09:06 PM

Went through many gas caps. Found the O'Reilley Auto parts caps work best. Cost me only $5.20 to replace hte last one I left on the truck box after filling up.

texanidiot25 · 09-01-2009, 09:50 PM

Quote:

Originally Posted by captain

I bought a locking cap from LMC and gas would gush out of the keyhole whenever I turned right. It was a piece of garbage.

Exactly. I only fill to a 3/4 tank usually... And keep a wrag handy to save the paint some trouble.

LMC, Lost More Cash...

09-01-2009, 02:10 PM	#1
epashhans Registered User Join Date: Jul 2009 Location: MT Posts: 319	Gas sucking out of my locking gas cap! So when I got the truck it had an older locking cap so I figured it had a leak or something and got a new cap. Now its still doing it! When I drive down the road its coming of the center of the cap and blowing down the side of my box! Has anyone has this before? Doesn't seem to do it when the tank is lower with fuel...but I want to be able to fill it up. Some kind of suction going on? I currently have an electric fuel pump going to a 454 with an edelbrock/carter on it. Anyone have any ideas? I did order a new gasket for the sending unit because it has a small leak...could that be causing it? Thats the next thing I am going to try! __________________ '67 C-10 Shorty - 454, 5spd, and speed holes!

09-01-2009, 02:17 PM	#2
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,016	Re: Gas sucking out of my locking gas cap! Sounds like you need a vented cap. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man RIP FleetsidePaul

09-01-2009, 02:57 PM	#3
epashhans Registered User Join Date: Jul 2009 Location: MT Posts: 319	Re: Gas sucking out of my locking gas cap! Wouldn't it just come out the vented cap as well? __________________ '67 C-10 Shorty - 454, 5spd, and speed holes!

09-01-2009, 03:30 PM	#4
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: Gas sucking out of my locking gas cap! Check the vent tube on the tank, since they tend to get pinched off sometimes against the body. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU Last edited by vectorit; 09-01-2009 at 03:30 PM.

09-01-2009, 03:59 PM	#5
Ace in the hole Registered User Join Date: Apr 2007 Location: Kalamazoo, Michigan, USA Posts: 538	Re: Gas sucking out of my locking gas cap! vented caps do it too, it happened on my 70 all the time with a new vented locking cap. 67-70 do not have a vented tank so you are kind of stuck with a vented cap and I don't think you can get away from some sort of spillage when the tank is full. __________________ 1970 K20, 350--- SOLD 05 silverado extended cab short box- duramax Jeep wrangler unlimited Last edited by Ace in the hole; 09-01-2009 at 04:03 PM.

09-01-2009, 04:09 PM	#6
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: Gas sucking out of my locking gas cap! Could it be the locking cap? I run a regular vented cap and can fill the gas tank pretty full with no spillage. __________________ Beat it to fit, Paint it to match...

09-01-2009, 05:39 PM	#8
westbrookw LET'S GO...MOUNTAINEERS Join Date: Oct 2007 Location: Williamstown, WV Posts: 339	Re: Gas sucking out of my locking gas cap! I had something similar with a mechanical pump. It was sending fuel back in the return. I had to replace the mechanical bc it ruptured inside. Maybe the pressure is too high on the mechanical. Not sure. __________________ 72 SWB/Step

09-01-2009, 05:46 PM	#9
captain Registered User Join Date: Aug 2002 Location: Austin, TX Posts: 59	Re: Gas sucking out of my locking gas cap! I bought a locking cap from LMC and gas would gush out of the keyhole whenever I turned right. It was a piece of garbage. __________________ Tommy Morgan 1969 Custom 10, 1998 C1500 My build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=605783 They say there's a sucker born every minute. They go to Ebay to be baptized.

09-01-2009, 09:06 PM	#10
olyeller70 Registered User Join Date: Feb 2007 Location: Atlanta Posts: 51	Re: Gas sucking out of my locking gas cap! Went through many gas caps. Found the O'Reilley Auto parts caps work best. Cost me only $5.20 to replace hte last one I left on the truck box after filling up. __________________ Thanks, Mike



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