onfire

iTrader: (17)

If you are trying to find a custom tank fuel level sender unit to work with a factory gage, these readings came from my 1999 fbod gage:

33 ohm = empty tank = 0.57V

68 ohm = empty tank = 1.05V

100 ohm = 1/16 tank = 1.40V

150 ohm = 3/8 tank = 1.84V

220 ohm = 7/8 tank = 2.30V

270 ohm = Full tank = 2.56V

I'm sure there is some variance in factory gages, but this should be close.

If the sender is disconnected, the gage reads empty.

At the rear bulkhead connection above the axle on the drivers side is the fuelpump and fuel sender wires. the 12v source to the fuel pump is gray, the ground is black. The two smaller diameter wires are purple and gray with a black stripe are for the sending unit to the gage. The purple wire sends a 4.96 volt signal to the sender (variable resistor) and it drops the voltage depending on your fuel level.

Hope this helps someone trying to wire up an aftermarket tank.

APD*98SS

did you have to connect both the purple and the gray and black??

onfire

iTrader: (17)

Yes, the two small wires (purple and gray/blk). This is for 1999 and up. 1998 is 0 to 80 or 90 ohms.

slayer1234

Do you know the Ohms for a 94 sending unit i need to replace it but i have no idea where to look. or do u know where i might find a replacement?

chpmnsws6

iTrader: (70)

is there a resistor out there that cuts total voltage in 1/2? I have a fuel guage but it only goes to 100 ohms full and I think 0 ohms empty

ty_ty13

iTrader: (42)

0-90ohms

xssive

iTrader: (123)

I also noticed in HP Tuners, you can adjust the ohm / level readings in the pcm

ty_ty13

iTrader: (42)

??

really?

chpmnsws6

iTrader: (70)

in 2.1

Red95Formula

glad to see that the lt1 sender is 0 -90 since that is the gauge I have.

Pro Stock John

iTrader: (34)

Interesting. I have to fix my gas gauge at some point.

Boostaholic

iTrader: (4)

Thanks for the info! I may make my own custom gauge, there are some sweet little PICs with ADC and enough outputs to drive a LED readout showing 0-99%

super_kev

iTrader: (5)

What do you mean by adjust the ohm readings? Does the PCM require the gas level for some sort of engine function? If you have a 0-90 ohm gas gauge, can you install a 0-90 ohm sender in the tank and then just wire it up to the 0-90 gauge?

xssive

iTrader: (123)

Adjust the ohm readings as in you set where each ohm-level point is... I.E. you set what ohm reading = full or empty and every point between

$750 L98

iTrader: (7)

Bringing this back from the dead to see if I can get and clarifications from some electrical gurus.

I had a stock 3rd gen gauge (0-90 Ohm) the stock resistors in the gauge were 22 Ohm (E), and 82 (F). So my reasoning was, match it up with something roughly similar for the 4th gen sending unit.

I rigged mine like this:

33 ohm = empty tank = 0.57V (I used a 47 Ohm)

68 ohm = empty tank = 1.05V

100 ohm = 1/16 tank = 1.40V

150 ohm = 3/8 tank = 1.84V

220 ohm = 7/8 tank = 2.30V

270 ohm = Full tank = 2.56V ( I used 220 Ohm)

So essentially if the sender puts out anything less than 47 Ohm, it will read empty? That would be great for me, i'd rather trigger empty early than too late. And with my 220 Ohm for the high side, anything the sender gives above 220 Ohm will trigger full? Again no big deal, on full - it will just read full a bit longer than normal.

Lonnies Performance

iTrader: (16)

Not sure what you are trying to do with a 3rd gen F-body, but if you are adding a 4th gen tank & want the gauge to work, I can get you the correct sensor for your gauge.

I also have sender replacements for the 99up cars.

TDMKR496

iTrader: (3)

This is great

99lowburb

So what would be the ohm range on a 1999 suburban Lt I have a fuel cell and I want to get the right sending untu for the cell

evilstuie

Old post I know, but just to add the extra info for those chasing it:

Adjusting the ohms values in HP Tuners only works if the OS you're using is from a vehicle that uses OBD2/serial data to control the gauges (i.e. 99-02 Firebird, Camaro etc)
It won't work if you're just trying to adjust it for an older style gauge cluster, as this takes the reading directly from the tank and is internally calibrated/set to fixed values.

I was trying to get the fuel to display on a custom android tablet dash only to find out the operating system in the PCM is not compatible.