6.0 in 87 r10

[shaved87]

i have a 87 r10 truck that i have transplanted a 6.0 in. on the stand alone harness i have one wire left out that is supposed to run to the fuel tanks. which wire would this be?? which one of the wires coming from the bulkhead comes on for three seconds then goes off ??

[87chevy.com]

is it a oe harness modified or like a painless harness? for mine, that wire is the ground side control to the fuel pump relay. once you set the relay up correctly i just spliced it into the factory dual tank switch's power feed (on the back of the connector). operates correctly.
clint

[shaved87]

any pics?? and yes its a original rewired harness

[87chevy.com]

pictures of the connector and how i wired it? no pictures on file here... im 99% sure the wire that i tied unto behind the fuel selector switch was purple and was probally a 10gauge wire.
clint

[glock35ipsc]

I wired mine to the tan/white wire that runs from the trucks original fuel pump relay to the selector switch to power it. Basically, the 5.3 harness has a wire that powers a relay. I used a Bosch 30A relay, not the trucks original one. Then I ran a wire (the brown one) from the new relay to the tan/white wire. I tied into that wire at the firewall.

* Edit - Forgot to add.... the wire that triggers the fuel pump primer is the red wire coming off the trucks original fuel pump relay. You wont need that one, just the tan/white to the switch is all you need to deal with.

[shaved87]

since i have two tanks there are two tan/white wires that goes into the fuse block. should i tap on to either one of these?? and which red wire are u talking about?? is it a direct 12v wire?? thanks for all the help

[glock35ipsc]

The tan/white wire (just one) I'm talking about runs from the fuel pump relay on the firewall directly to the switch on the dash. You just need to send power from a relay (triggered by the 5.3's harness wire) to that wire. That will send power to the switch, which will in turn send power to the tank selector valve and the corresponding fuel pump.

As for the red wire, you asked:

which one of the wires coming from the bulkhead comes on for three seconds then goes off ??

That is the red wire coming off the OE fuel pump relay, and you will not need it so don;t worry about it.

[shaved87]

thanks man what are you guys using for the brake booster is there a hose on the intake that i can use for brake booster vacuum

[glock35ipsc]

On the drivers side rear of the manifold, there is a vacuum port there. If there is no nipple on yours, you can get one from GM.

See page three on this write up from S&P:

http://www.hotrodlane.cc/PDFFILES/Lisa%20Tahoe.pdf

[shaved87]

how are you guys makin your aftermarket gauges work?? as well as tach??

[87chevy.com]

one wire at a time?? lol. you would need to get a 90-91 suburban/jimmy cluster with electronic speedo. re pin the back of the factory trucks harness to match the suburbans printed circuit board. as far as the oil - facotry lsx oil sender.. doesnt needle is strait up, you could get an overlay for the factory gauge, but other than that oil gauge works. water temp, use the autometer temp sensor and adapter. i couldnt find a gm sensor that fit in the head and had the 5v reference that the comptuer needs. Other members have removed the allen plug from the passenger head and made the adapter out of that... i tried and it didnt look as perdy so i just spend the 15 bucks on the adapter. rpm, aftermarket tach wired into the pcm on 4cyl mode.