Gas sender

Ok, thanks. Trunk has carpet glued down and every video I watched showed the tank out of the car to check sender. If I can get at it from inside trunk, would be much easier. My 12v gage is showing empty so it's either the gage or the sending unit I guess.
 
When the car was changed to 12v was anything done to the original gauge & sender?

Check for power to the gauge, just in case.
If you ground the yellow sender wire it should operate the gauge.

Trunk floor photo.
 

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I did not wire the car 6v to 12v. Whoever did the wiring sometimes has 3 colors going to one gage. 1 wire may consist of 3 colors, red, green and then orange from beginning to end of wire. That's dumb I think! I will try and ground the sender and see what happens. In your photo, what is the little cylinder with the one wire attached to it. I see one like it under my hood but it's not attached to anything.. The wiring needs to be checked one wire at a time. I can't even find a fuse panel on the car. A lot of work to do.
 
There is no fuse panel. All the important circuits go through a couple of circuit breakers under the dash up near the speaker. All other accessories (clock, radio, etc.) are fused individually.
 
Dobie Gillis is correct... no fuse panel.

If the back of your fuel gauge looks like the one below, it (and the sender?) were replaced with 12v reproductions. The 2nd photo below is an oem fuel sender, probably '55.

The silver cylinder is a noise suppressor capacitor that is connected to, and leftover from, the oem '55 sender. The tank and sender in the 'trunk floor' photo above are replacements, not original.
 

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Depending on which gauges you have the '55 & '56 versions may look the same. the 57's are most likely different. IIRC '56 oem gauges ran on 12v, without a voltage regulator.
The '57+ oem style gauges are actually lower voltage gauges but do use the 12 to 6 volt regulator.
 
Finally found time to check out the fuel sender. I pulled up the glued down carpet in the trunk to remove the lid to get at the sender. Previous owner used a lot of glue, took me 15 minutes just to pull the carpet, every inch was glued down ??? Took off the lid and no sending unit, not centered in opening, mounted toward rear and can't get to it. Guess next step will be to drop tank. I could cut the trunk floor to get at it but the floor metal is perfect so don't want to do that. I did ground the sender wire and the gage jumps to full, so I think the sender is bad. Going to order a new one.
 
Depending on what was done to the car to convert it to 12v, and if the fuel gauge was working correctly before, you'll have a couple choices of which sender to buy.
If you don't get the right one it won't work right when you're done.
(It's a corollary to Murphy's Law.)
 
If the sending unit is not accessible from the access hole in the trunk floor, it sounds like someone must have installed a gas tank from a different model car. In that case you need to be absolutely certain that the sending unit terminal is not touching body ground at the bottom of the trunk floor when the tank is installed. Also would be a good idea to run a separate ground wire down to a ring-tonque terminal attached to one of the sending unit mounting screws. If the sending unit still has an old condenser (capacitor) attached to the sender terminal, it might be bad. You should have it tested. Many people just remove them and throw them away. All they do is help make the movement of the guage needle slower when gas is sloshing in the tank from starts and stops.
 
Oilslickwillie said:
1 wire may consist of 3 colors, red, green and then orange from beginning to end of wire.

In your photo, what is the little cylinder with the one wire attached to it.

I see one like it under my hood but it's not attached to anything.

I can't even find a fuse panel on the car. A lot of work to do.
Click to expand...

The color coding is not original 55 Ford wiring.

The little cylinder is a condenser (capacitor).

Originally the only two condensers under the hood of a '55 Ford are located at the voltage regulator and at the back of the generator (besides the ignition condenser under the distributor cap). The generator and voltage regulator condensers were installed for radio frequency spike suppression equipment. If you are still operating the original tube radio, you may want to replace those. If you are using a modern radio, they normally have built-in suppression equipment. If so, take those old condensers off the VR and Gen and throw them away.

The '55 Ford is not equipped with a fuse panel. All fuses are inline type.
 
Thanks Dave, I won't know exactly what is in the tank until pulled. I will remember your advise on the fit. As for the wiring, whoever did some wiring was really sloppy. Instead of using one color length they pieced together whatever color wire they had available. When I have time, I will redo all that one wire at a time. Drives me crazy the way they did it.
 

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Oilslickwillie said:
Macs has one that is suppose to work, it's for 6 or 12 volt and suppose to fit 1955 Ford. 49-20528-2
Click to expand...
If you do a few minutes of detective work to figure out which parts and what the prev owner did to set up the fuel gauge it will increase your chances of getting the right sender the first time.
 
If grounding the wire makes the gauge read full, it is possible that the tank has lost its ground. Try clipping a jumper wire from the tank to a good body or frame ground and see if the gauge works. I always install a ground wire from the sending unit to a ground so that tank grounding isn't an issue. John
 
Grounded the tank to the frame. Actually I used my Drexel tool to get to bare metal, grounded, needle stays at empty. Thinking it must be the sender.
 
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