Gbody 0-90 ohm to LS1 PCM Project

stevej

Not-quite-so-new-guy
Oct 7, 2020
7
3
Hey guys,

I'm new to the threads but have been learning from these sites for some time now. I've done an LS1 Swap on my 84 Regal.
I am currently working on the fuel sender and getting it to work with the PCM. I've seen a lot of options but here is what I am currently working on.

(Pic 1 and 2 )I pulled a resistor off of a bad board here at work and (its the bosses old mini-fridge for his RV) I found a 100 ohm resistor (color code is brown, black, black, gold) and desoldered it (you can snip it if its long enough) then soldered it to wire on both ends.
You can find them on anything just gotta know what you are looking for. Test it to be sure it is working with a multimeter. (Pic 3)

Pic 4once its soldered you put some heat shrink to help keep it safe, I double-sleeved cause I'm paranoid, you don't have to do that.

Pic 5 I have an aftermarket fuel gauge that is 0-90, instead of going to pcm I left it alone so that I can read it correctly for now and wired it into the slot in pic 5,

I know its not the best right now but its for calibrating first, once I have it dialed in I will splice the ends together (I may leave it, its not a huge concern for me)

that is where I am at right now, I will start to test my volume and level tables and calibrate it based on the fuel sender that does work properly.
I'm going to search for tables to see if this has already been done,

I hope this helps anyone trying to get their systems working with older tanks and gauges,
this allows me to retain my stock sender and matching gauge without the headache of trying to get it to work from the getgo with the pcm as well as calibrate it because it will be already reading correctly and all you are doing is dialing it in for data purposes
 

Attachments

  • Pic 1.jpg
    Pic 1.jpg
    159 KB · Views: 36
  • Pic 2.jpg
    Pic 2.jpg
    123.2 KB · Views: 33
  • Pic 3.jpg
    Pic 3.jpg
    118.4 KB · Views: 29
  • Pic 4.jpg
    Pic 4.jpg
    207.8 KB · Views: 31
  • Pic 5.jpg
    Pic 5.jpg
    69.9 KB · Views: 30

g0thiac

G-Body Guru
Sep 6, 2020
755
63
Hey guys,

I'm new to the threads but have been learning from these sites for some time now. I've done an LS1 Swap on my 84 Regal.
I am currently working on the fuel sender and getting it to work with the PCM. I've seen a lot of options but here is what I am currently working on.

(Pic 1 and 2 )I pulled a resistor off of a bad board here at work and (its the bosses old mini-fridge for his RV) I found a 100 ohm resistor (color code is brown, black, black, gold) and desoldered it (you can snip it if its long enough) then soldered it to wire on both ends.
You can find them on anything just gotta know what you are looking for. Test it to be sure it is working with a multimeter. (Pic 3)

Pic 4once its soldered you put some heat shrink to help keep it safe, I double-sleeved cause I'm paranoid, you don't have to do that.

Pic 5 I have an aftermarket fuel gauge that is 0-90, instead of going to pcm I left it alone so that I can read it correctly for now and wired it into the slot in pic 5,

I know its not the best right now but its for calibrating first, once I have it dialed in I will splice the ends together (I may leave it, its not a huge concern for me)

that is where I am at right now, I will start to test my volume and level tables and calibrate it based on the fuel sender that does work properly.
I'm going to search for tables to see if this has already been done,

I hope this helps anyone trying to get their systems working with older tanks and gauges,
this allows me to retain my stock sender and matching gauge without the headache of trying to get it to work from the getgo with the pcm as well as calibrate it because it will be already reading correctly and all you are doing is dialing it in for data purposes
So basically to make the fuel gauge work with that engine comp, you have a resistor in series from the white sending wire coming from the tank?
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
4,205
113
Western MN
Are you running a camaro/firebird gauge cluster in your car?

Just not sure if you are running stock G body or aftermarket standalone gauges what you gain as the ECM doesn't do anything with the fuel signal input.
 

stevej

Not-quite-so-new-guy
Thread starter
Oct 7, 2020
7
3
Sorry about that
I’m using an aftermarket gauge that does 0-90 so i can get a proper read.

Eventually i want to move away from this to have an obd2 system that ive been looking at. I just ordered it and waiting for it to arrive.

I attached a picture of where i pulled the wire.

my instrument cluster had no gauges except fuel and speedo (which was broken ) being it was a carb v6. So I needed to replace the whole instrument cluster.

While my fuel reads fine, I’m hoping to have everything eventually integrated into the pcm so i can track things better.

Once i dial in the tables for fuel I’ll send it to you guys. But it will be awhile as i want to make sure it’s accurate.

My project has primarily been get it going and then tweak as needed.
 

Attachments

  • 91EB0CBE-4BDD-4E5B-A56C-001DFB62A1D6.jpeg
    91EB0CBE-4BDD-4E5B-A56C-001DFB62A1D6.jpeg
    191.3 KB · Views: 29
  • image.jpg
    image.jpg
    1.1 MB · Views: 28
Last edited:

stevej

Not-quite-so-new-guy
Thread starter
Oct 7, 2020
7
3
So basically to make the fuel gauge work with that engine comp, you have a resistor in series from the white sending wire coming from the tank?
The reason for this is that when your sender hits 0ohm it will short the pcm so you’ll need any kind of resistor that puts it above 40 and below 240 to keep it safe.

I haven’t tested the theory on the short but better safe than sorry. It’sa few extra steps for something that isn’t in the way but can be calibrated over time.
 
  • Like
Reactions: 1 user

stevej

Not-quite-so-new-guy
Thread starter
Oct 7, 2020
7
3
Are you running a camaro/firebird gauge cluster in your car?

Just not sure if you are running stock G body or aftermarket standalone gauges what you gain as the ECM doesn't do anything with the fuel signal input.
I’m running complete aftermarket gauges.

I’m hoping to get this obd2 dash unit. If all goes well i can have a single display with everything integrated including fuel readings.

For now I’ll have the fuel gauge until its dialed in.
 

stevej

Not-quite-so-new-guy
Thread starter
Oct 7, 2020
7
3
So basically to make the fuel gauge work with that engine comp, you have a resistor in series from the white sending wire coming from the tank?
yes, but instead of going straight to the computer, I have it going to my aftermarket gauge and tap into there to go to the computer. you can do it either way, but I did this for now until I figure out my fuel levels
 
  • Like
Reactions: 1 user

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot Mike's Montes P-S-T Southside Machine Performance UMI Performance

Contact Admin@GBodyForum.com for info on becoming a sponsor