Fuel Pump Wiring

[JJAB]

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]

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

[68GMCCustom]

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]

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]

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

[JJAB]

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]

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]

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]

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]

Thank You!!!! Excellent information.

[JJAB]

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!!

[JJAB]

Seeking a little more help guys. A little background:

I put a 5.3 ls motor into a 1987 c10. I unhooked all factory wiring/sensors and laid them to the side. Only factory wires used were starter wires. To get to the point after installation, I can not get the fuel pumps or the tank selector switch or crossover valve to work. I am getting no power to the fuel pump relay, nor am i getting power tank selector switch or crossover valve. By unhooking the factory sensors, have I interupted a complete circuit. Anybody got any suggestions?