Autometer fuel guage not working

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68 A

68 A

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Hi,

I have an autometer fuel guage (#4315) that i just put in the car and it is hooked up but does not work. I was wondering how to correctly hook it up to work with our cars. According to the instructions it is correct. I tested the ohms at the sending wire on the guage and it read OL, and it also read OL at the sending unit. When i put it on volts, it read 4.2 volts at both ends. I dont think it is supposed to run that many and that is why it is not working. Did i get the wrong guage? It appears to be grounded.

Also, why can't i do a 2 word search? i tried searching "fuel guage", but i get posts that have only "fuel" or "guage" in them, and not "fuel guage"

edit: and now when i post this, it gives me similar posts that i was looking for with the search window, which did not find what i was searching for.

i'm going to double check the ground now

Thanks,

Steve
 
All of the Autometer fuel gauges that I have worked with use a 12v power source, not the 5v the most dodge gauges work on.

Can you supply a part # for that gauge?
 
autometer number 4315, 73 OHMS empty/ 8-12 ohms full, for most fords before 1989 and most chrysler vehicles.

thats right of the box.

I do have it wired so that it is 12 V, i checked the power into the guage and it is 11.8 V with the car off.

Still about 4 V on the wire to the sending unit at the guage and sending unit.

I ran a jumper wire from the fuel line to the rear to double check the ground, but I still have 4 V at the rear, and OL displayed when i switch the meter to OHMS.

There is probably only 3 gallons in the tank, so the reading should be low, but i have no idea what the voltage is supposed to be.

Thanks,

Steve
 
There shouldn't be any voltage through the sender wire (you're probably seeing feedback in the circuit). That wire, when connected to the sender in the tank, measures resistance relative to ground (the approx 9-72 ohms).

If you have 12v connected to the proper terminal, and the ground terminal properly grounded, when you connect a jumper from the "S" terminal to a ground, the gauge should immediately peg on "full". If you get no movement then contact Autometer - they'll send a replacement.

One I installed wasn't calibrated correctly. It read 1/4 full when there was no fuel in the tank. I sent it back and they sent me a replacement that worked correctly.
 
i grounded out the S terminal and the guage pegged, so the guage is good. Where would feedback be coming from?
 
ok, did some more checking with the multimeter

Key on:

-Wire from gas tank sending unit connected to S terminal - 4 Volts, OHM is OL

-Wire from gas tank disconnected from the S terminal - 5 Volts on the S terminal of the Fuel guage, 78 OHM from the disconnected wire from the fuel sending unit

Key Off:

-Wire disconnected from the S terminal - Wire has 78 OHMs, S terminal on the guage has 35 OHMs

-Wire connected to the S terminal - 22.7 OHMs at the terminal.


so by looking at this, the guage is putting 5 volts out the S terminal? Thats all i can figure out, maybe the guage is bad?

Thanks,

Steve
 
I've always had stock gauges and never changed to a aftermarket fuel gauge. I wished I could help. I will over this coming winter change out my stock dash gauges to Autometer so I'm watching this thread just in case I run into the same problem. Maybe someone will come in and help soon.
 
i think mine is the sending unit becasue its either the gauge or the unit
 
I replaced all gauges with Autometer and used the factory harness by modding the connector.

You've already verified that the gauge works by grounding the "S" terminal.

I would check continuity of the dark blue wire (fuel sender) from the front to the rear. Disconnect it from the sender and the gauge while checking. It should have little to no resistance. You should also find no voltage present in the wire while disconnected. If you do, there's a short circuit somewhere.

You also need to verify that the sender is working. (If it worked before with the old gauge, then it's probably fine). Make sure the ground strap on the sender is still in place and secure. If the sender loses it's ground, you'll get no gauge reading.

Just for grins, make sure you've got an adequate amount of fuel in the tank.

Once you do get the gauge working, bear in mind that the Autometer fuel gauges are very non-linear, unlike the stock one. It will behave differently.
 
thanks for the replies,

the sending unit was new 3 years ago (replaced shortly after i bought the car), but the stock guage never worked and i thought it was the guage. So i think the sending unit would be good since it is only 3 years old.

Maybe it is a problem with the wire, I could get a jumper wire from the guage to the sending unit and that would also clear up any problems with the current wire. I will try testing the resistance.

I keep putting 2 gallons at a time in the tank when i go to town, maybe next weekend the car will get there on its own power and get a full tank.

But the amount of work i get done on the car this week will depend on when and if it rains.

Thanks,

Steve
 
Ok here we go.

I got my new Autometer MCX series gas gauge installed and of course it isn't reading correctly with the amount of fuel in the tank. The gauge comes with a sending unit but it is the type that needs to be installed vertically. The sending unit reads 248 ohm empty and 31 ohm full. In the instructions it states that the gauge has to have a 240-33 ohm sender. Now with my stock sending unit I have 12 ohm full and 8.95 volts with the key on. I have not checked the ohms with it empty.

I first started with a empty fuel tank and seeing what the gauge read connected to the stock sending unit (worked fine with stock gauge). The Autometer gauge read between 1/2 and 3/4 with the tank empty. I tried to install resistors and got the needle right on the empty but when I filled up the tank today it only goes up to 1/4 of a tank. I new it was a long shot with the resistors but I didn't know what else to do.

The entire car has been freshly rewired with a EZ wiring fuse box and wiring.

Where do I need to go from here?
Do I have a short somewhere with almost 9v on the sending unit wire?

Help!
 
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