ghettocruiser

iTrader: (17)

Hey everyone. I have a fuel tank from a 99 Z28. That and all other LS1 related drivetrain parts are in my 87. The car was sitting for about a month while i was working on it with about a gallon of gas in it.

I installed a prorammable fuel level gauge, went to the pumps to fill it up, programmed the gauge per the instructions, and the gauge just read E. So...I figure maybe I messed up or something is wrong with the gauge.

So I was driving home last night, and I noticed that if I swerved, or tapped on the brakes...anything to make the car lurch...the gauge would sweep from empty to full then back to empty. Sometimes on the way back down to empty it would stop and go back up to full.

Seems like the fuel sloshing in the tank is what is triggering it. Im going to check behind the dash and make sure its not a wiring issue behind the dash or behind the gauge. But if I dont find a short or issue back there, is there any way something in the tank could have gotten messed up? maybe something seized from sitting with no gas, then when I filled it the float moved and disturbed it enough to break it??

Any ideas are welcome! Thanks!

Justin

onfire

iTrader: (17)

270ohm full 33ohm empty for a 99 tank. Most fuel gages that read that high are the opposite of the factort gm sender......270 empty 33full.

ghettocruiser

iTrader: (17)

Its a programmable gauge.... Meaning it has a range from 0-280 in either direction. You set it at the empty reading, and set it at the full reading. (start calibrating when empty, it captures the resistance reading and saves that as empty. then you fill the tank, and capture that reading, and it saves it as full)

I havent been able to tell if its moving backwards. I think its loosing the signal to the gauge though. Because it sweeps all the way to full then right back down to E. So something just isnt right. Im going to take a resistance reading at the purple wire from the tank. If Im getting a good reading there, it has to be a guage power/ground issue. We'll see. I might mess with it today some. I just hate tearing my dash apart...again...

Justin

onfire

iTrader: (17)

If it's an Autometer adjustable....I tried on and could not get it to work with the fbod sender...they mumbled and took it back.

ghettocruiser

iTrader: (17)

Damn it... are you serious???? What did it do when you had it installed? Anything???

Mine was goin crazy today. I could move a wire and it would flip back and forth. So I re-soldered the wire, and it seemed ok. Then on my way to the pumps again, it was moving all over. Re-calibrated it. Now nothing. Sits on E. WTF....

Justin

Edit: I just cant figure out why it wouldnt work... The LS1 sender is well within the range of the adjustable gauge which goes from 0 - 280 ohm. All the gauge should be doing is measuring the resistance. Which moves with the sender. The only thing I can think of is the direction is wrong. But that doesnt explain why it jumps around all crazy like either... Im gonna try to mess with wires some more. See what happens.

onfire

iTrader: (17)

Autometer was having some QC problems with the adjustable guage when I bought mine.

ghettocruiser

iTrader: (17)

Well how long ago did you buy it??? So it was just a guage issue and not a compatability issue between the sender and the gauge? What did you end up doing for a gauge...or did they get it straight?

Sorry for all the questions. I just cant see how a company like autometer cant make something that works for such a common car on the roads today.

I wonder if they could adjust the gauge they offer that is close to read the range for the LS1 tank.

Justin

onfire

iTrader: (17)

Since I was using a custom tank, I changed the sender out and bought a standard gauge.

I bought it last fall. Call their tech line. They can be helpful if it's a trouble shooting problem.

ghettocruiser

iTrader: (17)

Definetly gonna call them. I want to check out wiring some more. Also... I checked for DTCs. I found one that might shed some light on things. P0463... Fuel Level Sensor Circuit High Voltage.

Im not sure what this means in terms of the gauge not working correctly, but obviously there is a problem somewhere.

Im using the 99 fuel tank, with all the wiring from the 99 car. Ground wire is attached under the rear seat which Im going to check out. All the previous wires that went into the PCM for EVAP are there as well as fuel pump wiring. I originally had the purple fuel level wire running only to the gauge. I later found two codes for fuel level and learned that the EVAP system needs fuel level input. So...I ran a jumper wire from where the purple fuel sender wire met up with the gauge wire. I ran the jump over to the PCM input. Codes went away...everything seemed fine.

So, I either have a wiring issue, an issue with the actual tank sender, or the gauge is screwy. I might be inclined to think its a wiring issue at this point. Like I said, Im going to check out all the grounds for both the car wiring and the gauge. Maybe give the gauge a new ground. And Ill check all the connections behind the gauge.

If I still dont find something, Autometer and I will have to have another conversation.

Thanks for the help!!

Justin

ghettocruiser

iTrader: (17)

Hmmm... Ok. I have a thought. I had the old autometer in the car when I started doing the exhaust work. I installed the new gauge while the car was down. I also wired a jumper wire from the purple fuel level wire, over to the PCM. I hadnt driven the car inbetween or anything. Im wondering if that jumper wire going over to the PCM is messing things up...

I might try clipping that wire. Ill probably get the DTCs for the evap needing the fuel level again. But if the gauge works, then Ill have to figure something out. That purple wire was never meant to have a gauge hooked up to it. It was supposed to go right to the PCM, and the PCM sent the data to the cluster.

Might be worth a shot...Ill deal with the wire that needs to go to the PCM later.

J.

ghettocruiser

iTrader: (17)

IT FIXED!!! I disconnected the wire going to the PCM. Works just like its supposed to now.

I think the signal that the PCM was sending to the fuel level sender was messing with the gauge. And the gauge was in turn also messing with the PCM...which is where the P0463 code came from.

Now...only thing is, I dont know if my EVAP is working because the fuel level isnt being sent to the PCM. Thats something I have to look into.

J.

EDIT:... Guess who just emailed me. Autometer... The two guys I talked to on the phone didnt know jack. So I emailed them. Here is the response...

Hello.

Yes, that gauge will operate with your factory sender. You will need
to use the Custom Calibration feature since your sender is 40 to 250
ohms.
The sender wire is the purple wire from the sender to the PCM. You
would have to cut the purple so that the fuel level gauge is the only
thing running off of that wire.
Thank you.
Cory
Tech/Service

Figures...as soon as I figure it out on my own, they decide to be helpfull...