Truck have both a fuel pump and electronic fuel pump? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

slam59 · 10-05-2014, 03:27 PM

Just put a new fuel pump under the hood with a full tune up a month or so ago and after seeing cable that no longer is hooked up hanging down I see mounted on the frame rail an electronic fuel pump there with rubber lines connected to both ends. Do these trucks have both under hood and frame rail pumps? Also see a red wire not connected like maybe the dog pulled it off. What would the red wire go to ?

slam59 · 10-05-2014, 04:00 PM

The truck has dual tanks

**hatzie** · 10-05-2014, 04:32 PM

Not factory
The TBI trucks had a fuel pump in each tank but no frame rail mounted pumps on the squares.

cadillac_al · 10-06-2014, 07:09 AM

Ingenious, a primer pump to prime the system after the truck sits for a week or so. I have been debating using an electric fuel pump for years and years because my trucks don't get used every day. I just let them crank and crank until the fuel finally gets to the carb. I don't want to rely on an electric fuel pump though. Now, a primer pump that is used only occasionally could be the hot ticket.

Tucson38 · 10-06-2014, 11:00 AM

So how would the plumbing work on that? Would you be forcing fuel through the electric pump by using the mechanical pump? I assume you'd want the electric pump to be bypassed entirely under normal driving conditions.

Keith Seymore · 10-06-2014, 12:20 PM

I have a tank mounted electric fuel pump (Holley red) on both my '65 GTO and my '74 Chevelle.

I have the electric pump wired to a toggle switch. I use the electric pump during periods of high demand, like during a burnout and 1/4 mile run. The rest of the time I drive around on the block mounted mechanical pump and it simply draws through the electric pump.

Been set up that way for 50 and 41 years, respectively. The GTO goes 12.20s at 120; the Chevelle has been 9.80's at 136mph.

K

slam59 · 10-07-2014, 10:10 AM

I happened to notice it while under the truck on passenger side. told my mechanic about it and gonna let him look at it over the weekend. Has a red wire that looks like it was pulled off or snagged by one of my dogs that lays U see the truck once in awhile. We shall see

motornut · 10-07-2014, 12:34 PM

my 79 had one "hotwired" in up front,by the PO
said it was hard to start after sitting week
but turn key and never stopped pumping.
found the 1/4 return line seemed expanded/split.
found splits/breaks in other lines.(red area in 3/8 carb base/charcoal line
repaired to manual only and better now.

**hatzie** · 10-07-2014, 05:42 PM

Quote:

Originally Posted by motornut

my 79 had one "hotwired" in up front,by the PO
said it was hard to start after sitting week
but turn key and never stopped pumping.
found the 1/4 return line seemed expanded/split.
found splits/breaks in other lines.(red area in 3/8 carb base/charcoal line
repaired to manual only and better now.

Typical for trucks that are "loosing the prime" in the fuel system. The electric fuel pump is a bandaid on the leaking fuel lines.
I use an electric fuel pump to prime the 1990's 6.5L Stanadyne fuel filter system on my '76 & M1008... it's on a Y off the main fuel line with a shutoff valve on the filter. It's there for priming when changing the filter not used otherwise.

cadillac_al · 10-07-2014, 09:41 PM

Quote:

Originally Posted by Keith Seymore

I have a tank mounted electric fuel pump (Holley red) on both my '65 GTO and my '74 Chevelle.

I have the electric pump wired to a toggle switch. I use the electric pump during periods of high demand, like during a burnout and 1/4 mile run. The rest of the time I drive around on the block mounted mechanical pump and it simply draws through the electric pump.

Been set up that way for 50 and 41 years, respectively. The GTO goes 12.20s at 120; the Chevelle has been 9.80's at 136mph.

K

That sounds like a good set up Kieth, nice ET's too. I assume by "tank mounted" you mean mounted near the tank, like on the frame or something near the tank? Those Holly Red pumps are the only ones priced reasonable. I don't know why electric fuel pumps cost so much.

Keith Seymore · 10-08-2014, 07:39 AM

Quote:

Originally Posted by cadillac_al

That sounds like a good set up Kieth, nice ET's too. I assume by "tank mounted" you mean mounted near the tank, like on the frame or something near the tank? Those Holly Red pumps are the only ones priced reasonable. I don't know why electric fuel pumps cost so much.

Correct; either on a small bracket or on the "waterfall" of the trunk floor itself.

The fuel supply line comes out of the tank, through the electric pump and then on up the frame rail to the mechanical pump.

K

10-05-2014, 03:27 PM	#1
slam59 Registered User Join Date: Nov 2011 Location: So. Calif Posts: 305	Truck have both a fuel pump and electronic fuel pump? Just put a new fuel pump under the hood with a full tune up a month or so ago and after seeing cable that no longer is hooked up hanging down I see mounted on the frame rail an electronic fuel pump there with rubber lines connected to both ends. Do these trucks have both under hood and frame rail pumps? Also see a red wire not connected like maybe the dog pulled it off. What would the red wire go to ? __________________ 1974 C10 swb 350 1977 3/4 ton Silverado 454 1999 2 door 2wd Tahoe

10-05-2014, 04:00 PM	#2
slam59 Registered User Join Date: Nov 2011 Location: So. Calif Posts: 305	Re: Truck have both a fuel pump and electronic fuel pump? The truck has dual tanks __________________ 1974 C10 swb 350 1977 3/4 ton Silverado 454 1999 2 door 2wd Tahoe

10-05-2014, 04:32 PM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Truck have both a fuel pump and electronic fuel pump? Not factory The TBI trucks had a fuel pump in each tank but no frame rail mounted pumps on the squares. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

10-06-2014, 07:09 AM	#4
cadillac_al Registered User Join Date: Oct 2013 Location: Maine Posts: 2,376	Re: Truck have both a fuel pump and electronic fuel pump? Ingenious, a primer pump to prime the system after the truck sits for a week or so. I have been debating using an electric fuel pump for years and years because my trucks don't get used every day. I just let them crank and crank until the fuel finally gets to the carb. I don't want to rely on an electric fuel pump though. Now, a primer pump that is used only occasionally could be the hot ticket. __________________ 76 Chevy K20 76 GMC K15 77 Chevy C10 77 Chevy K10

10-06-2014, 11:00 AM	#5
Tucson38 Registered User Join Date: Aug 2011 Location: Tucson Arizona Posts: 164	Re: Truck have both a fuel pump and electronic fuel pump? So how would the plumbing work on that? Would you be forcing fuel through the electric pump by using the mechanical pump? I assume you'd want the electric pump to be bypassed entirely under normal driving conditions.

10-06-2014, 12:20 PM	#6
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,226	Re: Truck have both a fuel pump and electronic fuel pump? I have a tank mounted electric fuel pump (Holley red) on both my '65 GTO and my '74 Chevelle. I have the electric pump wired to a toggle switch. I use the electric pump during periods of high demand, like during a burnout and 1/4 mile run. The rest of the time I drive around on the block mounted mechanical pump and it simply draws through the electric pump. Been set up that way for 50 and 41 years, respectively. The GTO goes 12.20s at 120; the Chevelle has been 9.80's at 136mph. K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/

10-07-2014, 10:10 AM	#7
slam59 Registered User Join Date: Nov 2011 Location: So. Calif Posts: 305	Re: Truck have both a fuel pump and electronic fuel pump? I happened to notice it while under the truck on passenger side. told my mechanic about it and gonna let him look at it over the weekend. Has a red wire that looks like it was pulled off or snagged by one of my dogs that lays U see the truck once in awhile. We shall see __________________ 1974 C10 swb 350 1977 3/4 ton Silverado 454 1999 2 door 2wd Tahoe

10-07-2014, 12:34 PM	#8
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Truck have both a fuel pump and electronic fuel pump? my 79 had one "hotwired" in up front,by the PO said it was hard to start after sitting week but turn key and never stopped pumping. found the 1/4 return line seemed expanded/split. found splits/breaks in other lines.(red area in 3/8 carb base/charcoal line repaired to manual only and better now. Attached Images __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350



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