My fuel gauge is not working, so I need to get hold of one. I bought a new fuel sending unit from Dennis Carpenter, and the empty shows 90 ohms. Does any one have a recommendation as to where I can find a gauge?

 

The stock sending unit uses the The King-Sealy (Ford Stock) principle. These sending units supply a full 6V through the heater wire in the gauge in the form of a square wave with the duration of the "on" being the variable determining the gauge reading. The longer the duration, the more fuel in the tank. It is this full 6v of current which heats the bi-metallic strip in the stock gauge that causes the gauge to read via a small gear train (that may adjustable?). Most after market sending units are simply a variable resistor which sends a constant voltage to the gauge, lessening that voltage as the fuel level goes down. Therefore, the sending units signal doesn't heat the bimetallic strip in the gauge as much. Unfortunately, the calibration of the after-market sending units and the stock gauges don't match up very well due to the differences in the principle of the signal.

The Ford Shop manual (pg 275) states to test the gauge, supply it with 1.5 Volts DC and it should read about 1/2 way. For your 49, you can use gagues from 48-50. The Oil Pressue Gauge is has the same internals as your fuel gauge with a different face, so if you find an Oil Pressure Gauge, you can swap it's face with your fuel gauge and use it. It may be possible (don't hold me to it) to also face swap with any gauge from a 51-52 with exception of the Amp Meter.

I've gotten most of my dash cluster parts off of EBay. Currenly, they have a rather ugly looking dash set, but the gagues look decent:

1948 49 50 Ford Truck Dash Cluster Gauges Speedometer Housing | eBay

 

Below is the gauge from a 54. The resistor wire on this one is fried. Someone probably hooked up a 12 volt battery to it and poof. I ran out of gas tonight so I gota get my fuel gauge working. Good luck on yours.

 

DAS,

I have heard of electronically inclined people replacing the resistor wire in their gauge housings by simply matching the gauge, length, resitance, and number of coils of the old wire.

~Brian

 

Thank you for your help. I forgot to say that I have changed to a 12 volt system, and I apologize for forgetting to mention this. I see that there was allot of effort put into your replies.
The sending unit has a range of 88/94 ohms empty and 14/18 ohms full, I have seen several aftermarket gauges; one of them is 73 ohms empty, and 8/12 ohms full. I don't want to spoil the original look of the dash, so I plan to place the gauge inside the ash tray compartment , or bolted to the tool tray on top of the fuel tank.
If anyone has any suggestions on the make and model of the gauge please let me know.

 

Fix the gauges and use the stock ones. Put a voltage regulator in the power wire before the gauges. This website has a nice how to if you want to make your own: 12 to 6 Volt Regulator
I didn't want to mess with the heat sink so I am making my regulator with the V7806-2000 part number. I ordered it from Digikey. The specification sheet includes capacitor values to use for voltage regulation, see "Positive Output" on page 4: http://www.cui.com/Product/Resource/...V78XX-2000.pdf
If you just want to purchase a regulator several vendors make solid state units; on ebay you can buy one for around $25.

 

Instrument cluster.