bed mounted aluminum tank and two bottom nipples - The 1947 - Present Chevrolet & GMC Truck Message Board Network

88Stanger · 08-24-2017, 11:52 PM

ok guys, building the 69 from ground up and have a 5.3 im building to put in with injection and was wondering the two nipples on the bottom of the bottom of the tank, one is for feed line and other, use it for return line? i have a nipple on the top but i use that for a vent.
Thanks in advance for any help

**mongocanfly** · 08-25-2017, 12:17 AM

whose the tank manufacturer? ..are you running a intank pump or external? or how are you doing your fuel pump setup?...pics might help

aggie91 · 08-25-2017, 09:21 AM

Typically both of those are outlets. Not a good idea to use one as a return. Just cap off the one you do not use.

Does the tank only have one fitting on the top? Would not be hard to ad another bulkhead fitting to the top of the tank for the return line.

BR3W CITY · 08-25-2017, 09:57 AM

Its for dual feed. Thats the low point on the tank, so putting the return there would make the return fuel fight the pressure at the sump from the weight of the fuel.

88Stanger · 08-25-2017, 05:20 PM

I'll be running an external pump to the LS. I had the idea to install another fitting on top, but others are saying that this is bad and causes bubbles in fuel that cause issues with fuel injection. They LSX forum say to use the two bottoms as one for in and on for return, illuminating bubbles in fuel.

BR3W CITY · 08-25-2017, 06:46 PM

IMO, they say that because they read it somewhere on the same forum. Yes, I know the "Bubble" thing, but after lord knows how many vehicles being built and tuned...from 350hp to 1500+, I have NEVER had a vehicle see a failure related to bubbles in the fuel.
Theoretically, if you had like a 1L tank where there was no fuel volume, it would be possible to create bubbles that somehow got sucked into the pickup, and forced into the lines....but that would have to be a tiny tank, and a LOT of bubbles. Surface tension on gas is low, it doesnt' bubble well.

The last tanks I've purchased all had 2 ports on top, 2 on bottom. On upper for return, one upper for vent w/rollover check, the sumped 2 on the bottom for feed.

88Stanger · 08-26-2017, 06:09 PM

my new aluminium tank has the filler tube, sending unit and one nipple on top then two nipples on bottom.

08-24-2017, 11:52 PM	#1
88Stanger Registered User Join Date: Mar 2015 Location: Washington State Posts: 1,654	bed mounted aluminum tank and two bottom nipples ok guys, building the 69 from ground up and have a 5.3 im building to put in with injection and was wondering the two nipples on the bottom of the bottom of the tank, one is for feed line and other, use it for return line? i have a nipple on the top but i use that for a vent. Thanks in advance for any help

08-25-2017, 12:17 AM	#2
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,671	Re: bed mounted aluminum tank and two bottom nipples whose the tank manufacturer? ..are you running a intank pump or external? or how are you doing your fuel pump setup?...pics might help Last edited by mongocanfly; 08-25-2017 at 12:26 AM.

08-25-2017, 09:21 AM	#3
aggie91 I'm just glad to be here! Join Date: Jan 2008 Location: Longview, TX Posts: 4,788	Re: bed mounted aluminum tank and two bottom nipples Typically both of those are outlets. Not a good idea to use one as a return. Just cap off the one you do not use. Does the tank only have one fitting on the top? Would not be hard to ad another bulkhead fitting to the top of the tank for the return line. __________________ Karl 1965 Chevy Stepside(Grandpa's Old Blue) and (July 2015 Shop Build!)(2020, the Saga Continues) http://67-72chevytrucks.com/vboard/s...d.php?t=372424 The LST Challenge: http://67-72chevytrucks.com/vboard/s...=1#post7812257 Korbin's 1st Square: "Sunburn" http://67-72chevytrucks.com/vboard/s...d.php?t=418618 1985 GMC Sierra: "White Trash", Korbin's 2nd now... http://67-72chevytrucks.com/vboard/s...d.php?t=632305 Henry - 1984 Chevrolet, Owen's 1st Square

08-25-2017, 09:57 AM	#4
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: bed mounted aluminum tank and two bottom nipples Its for dual feed. Thats the low point on the tank, so putting the return there would make the return fuel fight the pressure at the sump from the weight of the fuel. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

08-25-2017, 05:20 PM	#5
88Stanger Registered User Join Date: Mar 2015 Location: Washington State Posts: 1,654	Re: bed mounted aluminum tank and two bottom nipples I'll be running an external pump to the LS. I had the idea to install another fitting on top, but others are saying that this is bad and causes bubbles in fuel that cause issues with fuel injection. They LSX forum say to use the two bottoms as one for in and on for return, illuminating bubbles in fuel.

08-25-2017, 06:46 PM	#6
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: bed mounted aluminum tank and two bottom nipples IMO, they say that because they read it somewhere on the same forum. Yes, I know the "Bubble" thing, but after lord knows how many vehicles being built and tuned...from 350hp to 1500+, I have NEVER had a vehicle see a failure related to bubbles in the fuel. Theoretically, if you had like a 1L tank where there was no fuel volume, it would be possible to create bubbles that somehow got sucked into the pickup, and forced into the lines....but that would have to be a tiny tank, and a LOT of bubbles. Surface tension on gas is low, it doesnt' bubble well. The last tanks I've purchased all had 2 ports on top, 2 on bottom. On upper for return, one upper for vent w/rollover check, the sumped 2 on the bottom for feed. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

08-26-2017, 06:09 PM	#7
88Stanger Registered User Join Date: Mar 2015 Location: Washington State Posts: 1,654	Re: bed mounted aluminum tank and two bottom nipples my new aluminium tank has the filler tube, sending unit and one nipple on top then two nipples on bottom.

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