Testing fuel sending unit
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Mountain Pass
Joined: Feb 2004
Posts: 197
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From: In the swamps of Florida
Testing fuel sending unit
I searched all through my Haynes manual and could not find the resistance specs for the fuel guage sending units. Does anyone know what the specs are supposed to be? Both of mine are bad (needle on ohm meter bounces all over I move the float from empty to full) and I don't want to pay out the *** for a new one, so I'm going to try and find a good one in the JY.
Cargo Master
Joined: Oct 2005
Posts: 2,295
Likes: 25
From: NJ
Not sure on the newer Fords but on anything I've touched from the 50s through 70s it has been roughyl 10 ohms to 73 ohms. Might be slightly different for new stuff but should be in the ballpark. Perhaps someone else here knows the exact specs.
Moderator
Joined: Jan 2001
Posts: 56,949
Likes: 2,718
From: Virginia
I believe it may be 10-90 ohms, but don't bother going to the junkyard and pulling down nasty old tanks. All of these trucks have sending unit problems, and it's a 99% chance the ones in the junkyard will be bad, or will only last 6 months and go bad. Start saving your money, or you can take them apart and fix them sometimes. I have had good luck doing this.
Moderator
Joined: Jan 2001
Posts: 56,949
Likes: 2,718
From: Virginia
You have to be careful. Just take some wire cutters and carefully get under the little tabs and bend them back. They hold the little metal box together. Hold the box together with your fingers, as some of them do have springs that are on the shaft to take the play out of the arm.
Carefully pull it apart and take a look. Sometimes the little brass wiper is cracked or completely broke off. I have had good success in taking a soldering gun and soldering these back together. If you find the little wires are broken, if it's broken on the end, you can usually solder that back together too. If it's in the middle you are pretty much sunk.
Also take a look at the float and shake it to make sure there is no gas in it.
When you are all done, use your meter on the ohms scale to make sure it works ok.
Carefully pull it apart and take a look. Sometimes the little brass wiper is cracked or completely broke off. I have had good success in taking a soldering gun and soldering these back together. If you find the little wires are broken, if it's broken on the end, you can usually solder that back together too. If it's in the middle you are pretty much sunk.
Also take a look at the float and shake it to make sure there is no gas in it.
When you are all done, use your meter on the ohms scale to make sure it works ok.
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