Chevy k20 fuel pump question - Pirate4x4.Com : 4x4 and Off-Road Forum

Chrisf · 03-28-2009, 06:08 PM

i have a 1977 chevy k20 with 2 fuel tanks. I want to put an aftermarket fuel pump on it but it have 2 lines into the pump and 1 line out to the carb. one of the lines in is 3/8" and the other is smaller. whats the smaller line for??? do I need it to keep the two tanks??? dose anyone have a diagram of the fuel system??

Thanks
Chris

grasshopper77 · 03-28-2009, 07:17 PM

The smaller one should just be a drain back line for excess fuel not used.

Why? Do you have a high performance engine? If its just stock a stock mechanical pump will do the job just fine.

HAPPYJOHN · 03-28-2009, 08:00 PM

Quote:

Originally Posted by grasshopper77

the smaller one should just be a drain back line for excess fuel not used.

Why? Do you have a high performance engine? If its just stock a stock mechanical pump will do the job just fine.

x2.

Chrisf · 03-28-2009, 08:35 PM

ya the stock one was not keeping up. I want to run a summit 100 gph pump they only have 2 ports 1 in and one out. so I can just plug the smaller line then?

grasshopper77 · 03-28-2009, 08:45 PM

Yah you can just plug the drain line.

trkklr77 · 03-28-2009, 10:32 PM

with after market pumps you sometimes have to runa regulator, some higher end regs have a dump/return line so you are not building up to much presure between the pump and reg.

Chrisf · 03-29-2009, 10:39 PM

cool thanks for the help

GMCTruxrule · 03-30-2009, 12:45 AM

Quote:

Originally Posted by trkklr77

with after market pumps you sometimes have to runa regulator, some higher end regs have a dump/return line so you are not building up to much presure between the pump and reg.

Very good advice.

wazzabie · 09-06-2009, 11:41 AM

The return line helps prevent vapor lock. It came with later k5 models. my 78 has a return line from the mechanical pump

trkklr77 · 09-06-2009, 03:23 PM

what came with later k5 models?

nearly every stock pump after 73 came with a return line.

03-28-2009, 06:08 PM	#1 (permalink)
Chrisf Registered User Join Date: Jul 2002 Member # 12662 Location: San Juan Bautista Ca. USA Posts: 895	Chevy k20 fuel pump question i have a 1977 chevy k20 with 2 fuel tanks. I want to put an aftermarket fuel pump on it but it have 2 lines into the pump and 1 line out to the carb. one of the lines in is 3/8" and the other is smaller. whats the smaller line for??? do I need it to keep the two tanks??? dose anyone have a diagram of the fuel system?? Thanks Chris __________________ 1943 Flat Fender Medic Special 4.3l/th350, dual toy t-cases D44/D60, on 38 tsl's and some other cool stuff 1998 dodge cummins 4X4 sled puller [url=www.sanjuanrockcrawlers.com] San Juan Rock Crawlers[/url]

03-28-2009, 07:17 PM	#2 (permalink)
grasshopper77 Registered User Join Date: Sep 2005 Member # 52872 Location: Where it's too damn cold. Posts: 310	The smaller one should just be a drain back line for excess fuel not used. Why? Do you have a high performance engine? If its just stock a stock mechanical pump will do the job just fine. __________________ [COLOR="gray"]Horsepower is like a Condom.....I would rather have it and not need it than to need it and not have it [/COLOR]

03-28-2009, 08:35 PM	#4 (permalink)
Chrisf Registered User Join Date: Jul 2002 Member # 12662 Location: San Juan Bautista Ca. USA Posts: 895	ya the stock one was not keeping up. I want to run a summit 100 gph pump they only have 2 ports 1 in and one out. so I can just plug the smaller line then? __________________ 1943 Flat Fender Medic Special 4.3l/th350, dual toy t-cases D44/D60, on 38 tsl's and some other cool stuff 1998 dodge cummins 4X4 sled puller [url=www.sanjuanrockcrawlers.com] San Juan Rock Crawlers[/url]

03-28-2009, 08:45 PM	#5 (permalink)
grasshopper77 Registered User Join Date: Sep 2005 Member # 52872 Location: Where it's too damn cold. Posts: 310	Yah you can just plug the drain line. __________________ [COLOR="gray"]Horsepower is like a Condom.....I would rather have it and not need it than to need it and not have it [/COLOR]

03-28-2009, 10:32 PM	#6 (permalink)
trkklr77 skullfuckery Join Date: Apr 2004 Member # 29016 Location: galt ca, because i wanted my own backyard Posts: 15,233	with after market pumps you sometimes have to runa regulator, some higher end regs have a dump/return line so you are not building up to much presure between the pump and reg. __________________ Impeach or revolt, which will it be? buy my quad http://www.pirate4x4.com/forum/vehic...00-2500-a.html I WILL TRADE FOR A ROAD WORTHY 55-57 or 71-87 CHEVY 2WD PICK UP

03-29-2009, 10:39 PM	#7 (permalink)
Chrisf Registered User Join Date: Jul 2002 Member # 12662 Location: San Juan Bautista Ca. USA Posts: 895	cool thanks for the help __________________ 1943 Flat Fender Medic Special 4.3l/th350, dual toy t-cases D44/D60, on 38 tsl's and some other cool stuff 1998 dodge cummins 4X4 sled puller [url=www.sanjuanrockcrawlers.com] San Juan Rock Crawlers[/url]

09-06-2009, 11:41 AM	#9 (permalink)
wazzabie Registered User Join Date: Sep 2009 Member # 141823 Posts: 5	The return line helps prevent vapor lock. It came with later k5 models. my 78 has a return line from the mechanical pump

09-06-2009, 03:23 PM	#10 (permalink)
trkklr77 skullfuckery Join Date: Apr 2004 Member # 29016 Location: galt ca, because i wanted my own backyard Posts: 15,233	what came with later k5 models? nearly every stock pump after 73 came with a return line. __________________ Impeach or revolt, which will it be? buy my quad http://www.pirate4x4.com/forum/vehic...00-2500-a.html I WILL TRADE FOR A ROAD WORTHY 55-57 or 71-87 CHEVY 2WD PICK UP

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