fuel ohm question

A

Anonymous

Guest
gunna be installing autometers soon, and was wondering what ohm fuel senders are in the tank factory in my 78 malibu? im sure a few of you know, any help appreciated
 

hp3445

Amateur Racer
Jan 25, 2009
116
0
0
Southern NJ
I was going to ask this same question. ( I looked back 8 months, and it's here!!). I knew it was a 0-90 sender.. but wanted to be sure.. thanks !!!

Anybody have any problems with Autometer set ups? Fuel Level is the last gauge I need for the dash.. Looks like a basic wiring job..
 

mean78malibu

Dragway Regular
Mar 15, 2008
998
0
16
Pittsburgh, PA and Philly Area
You shouldn't have any issues. Just make sure the gauge AND sender have nice grounds. Don't just connect them to random screws in the dash that look like they will be ok. It will pay off later on down the road. Mine worked great until the float fell off in the tank ](*,)
 

joye227

Amateur Racer
Jan 12, 2010
171
0
0
Florence, South Carolina
My cutlass has rally gauges and the fuel gauge is off, so I was thinking of buying and ultra lite fuel level to match my other gauges. My sending wire has a good ground. So I just ground the gauge and hook the sending wire up to the old sending wire going to the dash?
 

mean78malibu

Dragway Regular
Mar 15, 2008
998
0
16
Pittsburgh, PA and Philly Area
joye227 said:
My cutlass has rally gauges and the fuel gauge is off, so I was thinking of buying and ultra lite fuel level to match my other gauges. My sending wire has a good ground. So I just ground the gauge and hook the sending wire up to the old sending wire going to the dash?

I believe the gauge will require accessory power also, so you would need to connect that to the ignition somewhere or jump off another wire. Assuming your factory wire is good all the way back, you should be able to connect to it.
 

gbodystuff

Amateur Racer
Mar 30, 2009
260
0
0
Iowa
The last Autometer gauge cluster I installed was a set of Nexus ones-the fuel gauge was pretty goofy to figure out. I had a 0-90 ohm sender but the scrolling feature on the handheld (you guys who've used Nexus gauges know what I'm talking about here...) would not let me set it at 1/8 mark on an empty tank as per the instructions. After a lot of worthless Autometer tech calls, i decided to fart around with the settings and go with a "custom" calibration setting. Then I filled the tank to exactly 3/4 full by capacity and the gauge only read 1/2 full...wtf? so I just scrolled up once on the handheld and it took me to 3/4 tank on the gauge finally! What a friggin nightmare. Oh, and I verified the resistance at the sender and at the gauge and they were the same 89.4 ohms prior to filling the tank so my connections were ok. What was weird is that I got a reading of 67 ohms with the tank filled 3/4 of the way-I should have got a 23 or 24 according to Autometer. At any rate, it's all good now but it was a pain to say the least.
 

Doober

Moderator
Jun 2, 2003
14,704
1
38
Catalina, AZ
www.cardomain.com
mean78malibu said:
joye227 said:
My cutlass has rally gauges and the fuel gauge is off, so I was thinking of buying and ultra lite fuel level to match my other gauges. My sending wire has a good ground. So I just ground the gauge and hook the sending wire up to the old sending wire going to the dash?

I believe the gauge will require accessory power also, so you would need to connect that to the ignition somewhere or jump off another wire. Assuming your factory wire is good all the way back, you should be able to connect to it.
Yes, the fuel gauge will have a power and ground, and a third wire (pink, not pink and black, that is power to the cluster) will be the wire to the sending unit. Basically the fuel gauge is an ohmmeter, power (pink/black and black wires) is needed for the actual gauge, and the pink wire is the 'probe wire' that goes back to the sending unit, which is a variable resistor (aka potentiometer) that provides a ground for the 'probe wire' of the gauge. This is the same premise for water temperature, oil pressure/temperature, and just about any other gauge (besides voltmeters, ammeters, speedometers or tachomters).
 

joye227

Amateur Racer
Jan 12, 2010
171
0
0
Florence, South Carolina
I looked up under the car at the tank the other day. I saw the two wires coming from the sending unit. Black for the ground and it looked like pink for the sending unit. I think I'm all set. Now is the time to order the gauge.
 

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