fuel pump return line? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

low 84 · 07-04-2003, 01:07 PM

ok i'm changing my truck over from the stock style pump that uses a return line to a holley mechanical pump. one of the hard lines that runs from the tank to the pump is big and one is small. am i right in guessing the big line is the feed and the small line is the return?

BigRed · 07-04-2003, 01:51 PM

Sounds right to me. However I'm not positive. It makes no sense that they would run the larger line as the return.

*mike reeh* · 07-04-2003, 02:50 PM

if you only have two lines running from the tanks, then you probably dont have a return line. The smaller one is probably the vent. Does it go directly to the fuel pump or to the charcoal canister?

Is your stock fuel pump a 2 port or 3 port? If its a 3 port, it should have a return. 2 ports are just input from tank, and output to carb.

mike

low 84 · 07-04-2003, 07:46 PM

Quote:

Originally posted by mike reeh
if you only have two lines running from the tanks, then you probably dont have a return line. The smaller one is probably the vent. Does it go directly to the fuel pump or to the charcoal canister?

Is your stock fuel pump a 2 port or 3 port? If its a 3 port, it should have a return. 2 ports are just input from tank, and output to carb.

mike

yes i have a three port pump, and inlet outlet and return, i also had the vent line which i removed becuase i'm not running any emmsions equipment. the small line that connects to the fuel pump is the same size as the vent line was and then there is a bigger line goin to the fuel pump aswell. so i'm guessing this is the feed which is the only one i need to keep?

*mike reeh* · 07-04-2003, 08:04 PM

Hmm the two smaller lines are the same size? I find that hard to beleive. There should be a 3/8" which is feed, 5/16" which is the vent and believe it or not the 1/4" is the return. Things may have changed slightly over the years though. This IS general motors we're talking about, and just about anything is possible.

mike

low 84 · 07-04-2003, 11:29 PM

mabey i mistaked the 3/8 and 5/16 as the same size. but the 1/4 is the return? i just cut off the wrong line then, lol

07-04-2003, 01:07 PM	#1
low 84 Registered User Join Date: Jan 2002 Location: Houston, TX Posts: 2,144	fuel pump return line? ok i'm changing my truck over from the stock style pump that uses a return line to a holley mechanical pump. one of the hard lines that runs from the tank to the pump is big and one is small. am i right in guessing the big line is the feed and the small line is the return? __________________ '51 F100, backhalf with a narrowed 9 and coil overs, 18.5" mickeys, monte front clip, +400" sbc in the works '05 1500 Crew Cab RIP '84 swb 5/7 drop, solid cammed 408 w/ fully ported dart heads, th350 w/ 10 inch hughes, 12 bolt w/ 3.73 richmonds and a locker '80 swb 4x4 in progress: 7" lift, 350 th350/np205, d44 and 1.5" ORD tie rod, 14BFF w/discs , armored diff covers, 40" MTR's

07-04-2003, 01:51 PM	#2
BigRed Registered User Join Date: Jun 2002 Location: DFW, TX Posts: 1,680	Sounds right to me. However I'm not positive. It makes no sense that they would run the larger line as the return. __________________ Scott Shelbourne

07-04-2003, 11:29 PM	#6
low 84 Registered User Join Date: Jan 2002 Location: Houston, TX Posts: 2,144	mabey i mistaked the 3/8 and 5/16 as the same size. but the 1/4 is the return? i just cut off the wrong line then, lol __________________ '51 F100, backhalf with a narrowed 9 and coil overs, 18.5" mickeys, monte front clip, +400" sbc in the works '05 1500 Crew Cab RIP '84 swb 5/7 drop, solid cammed 408 w/ fully ported dart heads, th350 w/ 10 inch hughes, 12 bolt w/ 3.73 richmonds and a locker '80 swb 4x4 in progress: 7" lift, 350 th350/np205, d44 and 1.5" ORD tie rod, 14BFF w/discs , armored diff covers, 40" MTR's

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07-04-2003, 02:50 PM	#3
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 683	if you only have two lines running from the tanks, then you probably dont have a return line. The smaller one is probably the vent. Does it go directly to the fuel pump or to the charcoal canister? Is your stock fuel pump a 2 port or 3 port? If its a 3 port, it should have a return. 2 ports are just input from tank, and output to carb. mike

07-04-2003, 08:04 PM	#5
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 683	Hmm the two smaller lines are the same size? I find that hard to beleive. There should be a 3/8" which is feed, 5/16" which is the vent and believe it or not the 1/4" is the return. Things may have changed slightly over the years though. This IS general motors we're talking about, and just about anything is possible. mike



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