Hi everyone- new here, but have had my '66 convertible since 1975 (second owner). My car sat through a long fall/winter/spring storage. The carburetor was gunned up so my mechanic drained the old gas out, removing the gas tank. Ever since my gas gauge only goes up to 1/8 on the gauge no matter how much gas I put in, We have tried 3 different new fuel sending units and still have the same problem. Any ideas?
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davidlallee
1966 Mustang gas gauge question
Hi everyone- new here, but have had my '66 convertible since 1975 (second owner). My car sat through a long fall/winter/spring storage. The carburetor was gunned up so my mechanic drained the old gas out, removing the gas tank. Ever since my gas gauge only goes up to 1/8 on the gauge no matter how much gas I put in, We have tried 3 different new fuel sending units and still have the same problem. Any ideas?
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New fuel sending units aren't plug and play. They have to be adjusted to show full and empty.
Sent from my SM-N960U using Tapatalk
Sent from my SM-N960U using Tapatalk
New sending units don’t really work correctly, They are simply designed wrong. In your case though, I would bet it’s not a sending unit issue since you had the same problem with the original one. I hope they saved the original, dit is likely better than the new ones.
The gauge works this way. Power comes from the battery, goes to the instrument voltage regulator where it drops to 5V. From there it goes to the sender, then it grounds to the body. The more current that flows the higher a reading you get. The sender is a variable resistor. As the fuel level increases the sender float moves up changing the resistance. The more resistance the less current that flows and the lower the gauge reading. Since you are reading low, you have too much resistance. This can be due to a bad ground. Since the sender grounds to the fuel tank, and the tank was removed and replaced, I would bet you are not getting a good ground between the tank and car body. Try connecting a wire to the body of the sender and the other end to the battery negative tool. See if the gauge now reads correctly. If it does you have a grounding issue. Another possible problem can be the instrument Voltage regulator, but all the gauges would read low if it was bad.
The gauge works this way. Power comes from the battery, goes to the instrument voltage regulator where it drops to 5V. From there it goes to the sender, then it grounds to the body. The more current that flows the higher a reading you get. The sender is a variable resistor. As the fuel level increases the sender float moves up changing the resistance. The more resistance the less current that flows and the lower the gauge reading. Since you are reading low, you have too much resistance. This can be due to a bad ground. Since the sender grounds to the fuel tank, and the tank was removed and replaced, I would bet you are not getting a good ground between the tank and car body. Try connecting a wire to the body of the sender and the other end to the battery negative tool. See if the gauge now reads correctly. If it does you have a grounding issue. Another possible problem can be the instrument Voltage regulator, but all the gauges would read low if it was bad.
If the mechanic changed your sending unit, try to get your old one back. Hopefully they didn't trash it but most likely they did.
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