Fuel Pump Wiring - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JJAB · 07-24-2013, 02:49 PM

Guys, I am about to install or wire a 1987 C10 already equipped with dual tanks with the electric pumps inside the tanks, for the the 5.3 ls engine. My question is, the fuel pump wire off of the re-worked harness, to what wire will I hook it up to so that the tank selector switch still operated like factory? Thanks!!

Yes this truck is an original 1987 that came with the TBI engine and everything is was functioning properly before installing 5.3 engine.

JJAB · 08-12-2013, 10:53 AM

Come on guys a little help here. Will it be easier if I put an inline walbro pump on the frame?

68GMCCustom · 08-12-2013, 01:16 PM

leaving the tank switching alone and using one pump mounted between the tanks going to the motor sounds like the easiest thing to me.

JJAB · 08-12-2013, 04:21 PM

I was thinking the same thing. I thought about ordering a walbro external inline pump. Help me here, I also thought that it would be best to remove the fuel pumps in the tanks now so that the external pump doesn't have to pull fuel through them. What are your thoughts?

solidaxel · 08-13-2013, 09:46 AM

It may be helpful to read my thread on 87 to 78 fuel tank, on your fuel pump

JJAB · 08-29-2013, 04:31 PM

I put a 5.3 into a dual tank 1987 C10. The driver wants to continue to utilize both tanks. I would llike to place the fuel pumps in the tank like the factory pumps. I know that the fuel pump relay is located on the firewall. Currently, I do not have it plugged up. If I were to plug that relay back up, which wire do I tap into with the correct wire off of the ls pcm(that turns on the fuel pump relay with key).

BR3W CITY · 08-29-2013, 05:17 PM

I imagine that would be the "signal /input" side of most standard relays (which the FP relay is)

iirc 85 is ground, 87 is out to pump, 30/51 is HOT, and 86 is the trigger.

JJAB · 08-29-2013, 06:33 PM

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So of the above schematic, the 87 fuel pump relay is labeled a through f at the top, the correct location would be E, correct? This is where I would splice in the signal wire from the ls pcm

clinebarger · 08-29-2013, 08:02 PM

Quote:

Originally Posted by JJAB

So of the above schematic, the 87 fuel pump relay is labeled a through f at the top, the correct location would be E, correct? This is where I would splice in the signal wire from the ls pcm

Pin D (Dark Green/White) is the control circuit....The fuel pump control wire from the PCM hooks here. It should be Dark Green/White as well.

To run the pumps in the tanks (I highly recommend)....You need a high pressure switching valve http://products.pollakaftermarket.co...valve/42-159?#

JJAB · 08-30-2013, 10:18 AM

Thank You!!!! Excellent information.

JJAB · 08-30-2013, 10:24 PM

I need a bit more help guys. For some reason, the fuel pumps nor the switch over valve is operating. First question, the tan and white wire coming off of the fuel pump relay, using a test light, shouldn't it be hot with the key on?

Or, can someone tell me why the tank switching valve is not working? Its not the valve itself because I have test two other valves and still not working.

Could the relay be bad and causing this? P

Please help!!

07-24-2013, 02:49 PM	#1
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Fuel Pump Wiring Guys, I am about to install or wire a 1987 C10 already equipped with dual tanks with the electric pumps inside the tanks, for the the 5.3 ls engine. My question is, the fuel pump wire off of the re-worked harness, to what wire will I hook it up to so that the tank selector switch still operated like factory? Thanks!! Yes this truck is an original 1987 that came with the TBI engine and everything is was functioning properly before installing 5.3 engine.

08-12-2013, 10:53 AM	#2
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Re: Fuel Pump Wiring Come on guys a little help here. Will it be easier if I put an inline walbro pump on the frame?

08-12-2013, 01:16 PM	#3
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: Fuel Pump Wiring leaving the tank switching alone and using one pump mounted between the tanks going to the motor sounds like the easiest thing to me. __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

08-12-2013, 04:21 PM	#4
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Re: Fuel Pump Wiring I was thinking the same thing. I thought about ordering a walbro external inline pump. Help me here, I also thought that it would be best to remove the fuel pumps in the tanks now so that the external pump doesn't have to pull fuel through them. What are your thoughts?

08-13-2013, 09:46 AM	#5
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: Fuel Pump Wiring It may be helpful to read my thread on 87 to 78 fuel tank, on your fuel pump __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

08-29-2013, 04:31 PM	#6
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Re: Fuel Pump Wiring I put a 5.3 into a dual tank 1987 C10. The driver wants to continue to utilize both tanks. I would llike to place the fuel pumps in the tank like the factory pumps. I know that the fuel pump relay is located on the firewall. Currently, I do not have it plugged up. If I were to plug that relay back up, which wire do I tap into with the correct wire off of the ls pcm(that turns on the fuel pump relay with key).

08-29-2013, 05:17 PM	#7
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Fuel Pump Wiring I imagine that would be the "signal /input" side of most standard relays (which the FP relay is) iirc 85 is ground, 87 is out to pump, 30/51 is HOT, and 86 is the trigger. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

08-29-2013, 06:33 PM	#8
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Re: Fuel Pump Wiring So of the above schematic, the 87 fuel pump relay is labeled a through f at the top, the correct location would be E, correct? This is where I would splice in the signal wire from the ls pcm

08-30-2013, 10:18 AM	#10
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Re: Fuel Pump Wiring Thank You!!!! Excellent information.

08-30-2013, 10:24 PM	#11
JJAB Registered User Join Date: Sep 2010 Location: Waco,Texas Posts: 143	Re: Fuel Pump Wiring I need a bit more help guys. For some reason, the fuel pumps nor the switch over valve is operating. First question, the tan and white wire coming off of the fuel pump relay, using a test light, shouldn't it be hot with the key on? Or, can someone tell me why the tank switching valve is not working? Its not the valve itself because I have test two other valves and still not working. Could the relay be bad and causing this? P Please help!!



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