Ackattack1

iTrader: (7)

I started working on my wiring and have a few questions.

But first: 1968 C-10 with a 2005 5.3L. I'm using a 2004 Silverado 4.8L wiring harness and ECM. I also have a fuel tank from a 2000 Trans Am.

There are a few sets of wires for a fuel tank pressure sensor, and 2 sets for EVAP system.

Anyways, is any of this needed? I kinda wonder about the fuel tank becoming negatively pressurized as the fuel is used up. Or is the filler cap vented (or can I get a vented one).

Obviously being a 68 emmisions isn't a concern.

Other than these few little things everything seems pretty straight forward when you sit down and study the diagrams a little. Now getting the engine wiring harness to look pretty....that's a different story

I may have a few more questions as I get closer to firing up the engine

Quagmeyer

check out this site: http://www.lt1swap.com/wiringharness.htm Lots of good info in there.

I just finished rewiring my 5.3 harness, and I believe the tank pressure and evap wires were eliminated.

psiconversion

iTrader: (5)

Tank Pressure and evap can be eliminated. Should have the codes turned off in the PCM as well.

jj62

Can the tank pressure and Evap can be eliminated on a 85 El Camino with a
04, LS1 and still pass Calif smog?

Ackattack1

iTrader: (7)

Couple more questions:

I'm using a brand new EZ wiring harness for my truck at the same time as I'm wiring up the engine.

For the starter wire, the factory uses a relay setup, and according to lt1swap.com (great info on there btw) you can bypass all of this and just use the regular start wire, is this correct?

Also, lt1swap.com says you can remove the oil pressure sensor circuit. Is this used by the computer to shut itself down if it looses oil pressure, or is it just for a dummy light?

psiconversion

iTrader: (5)

Yes you can bypass the oil pressure. It is only used as a bypass when your fuel pump relay goes bad. When you are cranking at a certain oil pressure it will engage the fuel pump.

ls1nova71

iTrader: (4)

The oil pressure sender is just for the guage, they stopped using it for a fuel pump back up after the LT1.
It's only used by the PCM on newer engines with AFM if I remember correctly.

psiconversion

iTrader: (5)

I stand corrected. Double checked the schematic. Cant say using the oil pressure wasnt a good idea though

ls1nova71

iTrader: (4)

I'd say it definitly was a good idea, but they must have thought that the relays they make are better now. That's the only explination I could come up with.

ls1nova71

iTrader: (4)

Yes, just use the wire that comes from the ignition switch directly to the starter. (would have been the heavy guage purple wire on the original ignition switch, that also goes to the neutral safety switch if your truck was originally an automatic)

psiconversion

iTrader: (5)

Make sure that if you are tapping into the trucks ignition wire for anything you realize that it is a resistor wire and not 12-volts. The wire I am talking about is the 'braided looking' white wire in the engine compartment.