alex722607

iTrader: (3)

Hi all, I have been poking around and trying to understand how to get the 4th gen evap system to work with a 0-90 ohm fuel sending unit and our car and the pcm.

I know the charcoal canister is ample to do the job, but I am sort of hung up on the idea.

So is there any way?

alex722607

iTrader: (3)

I am thinking of this:

http://www.docskustom.com/shop/viewi...p?productid=32

anyone?

I was thinking of using it to convert the signal of the wire from the pcm to the guage.

alex722607

iTrader: (3)

anyone?

ghettocruiser

iTrader: (4)

Quick and dirty answer...

No way to get 4th gen system to work 100% without the LS1 PCM, BCM, and factory gauge cluster.

The EVAP system needs fuel tank pressure as well as fuel level to determine when to cycle the solenoid and vent the tank. This function requires the same circuit as our thirdgen gauges, or aftermarket gauges, use to read fuel level. So when you hook both up, it causes some issues. This is why the stock LS1 gauge cluster uses serial data to drive the fuel gauge.

The 5v signal sent to the sender from an aftermarket gauge interferes with the LS PCM's ability to determine fuel level, and therefore causes the system to not work...also causes the fuel gauge to not work.

FYI...if you ask Autometer, they will tell you that if you are installing an aftermarket gauge into an LS car, you will have to sever the purple wire coming from the tank sender from the PCM. This is the wire the fuel gauge will use to read level. Unfortunately this also renders the EVAP system useless. YOu will then need to turn off the codes to avoid CEL's and all.

Thats to the best of my knowledge. Some other guys have looked into this, but I dont know of anyone that has made it work 100% without swapping all of the LS components in.

J.

alex722607

iTrader: (3)

okay thanks

Dodgeman79

I know this post is a few years old but why do you need the BCM?
I did a 4th gen dash swap LS swap and I'm doing the 4th gen tank. I thought all the info was sent to the PCM?