1940 ford resistor
 

does the resistor under the dash have anything to do with the function of the gages,my gages always worked but all of a sudden are not working correctly.

Re: 1940 ford resistor
 

No, it is an ignition resistor only, 6 volt to 4.5 volt to coil. Check your grounds, that is the most common problem. Add a temporary ground wire and see it that helps, then you can go to each item and clean connections.

Re: 1940 ford resistor
 

thanks, tightened the grounds,all gages except fuel gage work, fuel gage goes from empty to past full, tried a new sender from drake no change.

Re: 1940 ford resistor
 

You may not have the correct sender for it to work properly. The replacements are resistance style senders and do not work the same as the originals. The one you replaced may have been of the newer style as well. Might see if you can find an original. You can test your gage with a 1 1/2 volt battery and a 3 volts battery (1 D cell and then 2 D cells). See what the gauge reads with the batteries. At 1 1/2 volts the gauge should read 1/2 scale.
Another test is to remove the wire from the gauge to the sender at the sender. With the ignition on and the wire removed the gauge should read empty, now at the sender end short the wire to ground and with the ignition on the gauge should read full (only do this for a short period of time as it can damage the gauge if left shorted for an extended period). If the gauge checks ok this way but goes to full when connected to the sender, there may be a short in the sender wire.

Re: 1940 ford resistor
 

My fuel gauge in my Mustang wasn't working so I took the wire off at the sender in the tank and shorted that out with a jumper wire. The gauge moved to full when I turned on the ignition (as JSeery says). If that works its your sender that is is stuffed.

GB

Re: 1940 ford resistor
 

Had you converted from 6 to 12 volts?
www.morrisgauge.com

Re: 1940 ford resistor
 

no,still 6 volts, sender is a bob drake unit,put in by the previous owner.

Re: 1940 ford resistor
 

Not positive but think all the replacement types are the resistance types. I have heard mixed reports on how well they work.

Re: 1940 ford resistor
 

The original sending unit operated in a very different manner than the aftermarket unit made currently. There are multiple forum topics in that regard. In short, if you are 6 volt, you should use an original sender. Many of my customers have found that the aftermarket units are inaccurate and they can damage the gauge.
www.morrisgauge.com

Re: 1940 ford resistor
 

I agree, I will look for an original, and contact you about checking it out or rebuilding it if needed. thank you