1965 Fuel Sending Unit Test Help!

[James W.]

[Mark M.]

Re: 1965 Fuel Sending Unit Test Help!

James connect the meter to the I and S terminals. It should read near 0 when the float is down and 90-100 when float is all the way up. It sounds like your unit may OK.

[Harry S.]

Re: 1965 Fuel Sending Unit Test Help!


James, just took an NOS unit out of the box, Zero ( 0 ) when the float is down, 92 when the float is up.

[James W.]

Re: 1965 Fuel Sending Unit Test Help!

Per Hinkley's instructions, I did that also. The readings were near 0 ohms when the float is in the raised position and almost 90 ohm when the float is pushed to the near the bottom of the tank. Again the opposite of what is written in Hinkley's test instructions.

James

James connect the meter to the I and S terminals. It should read near 0 when the float is down and 90-100 when float is all the way up. It sounds like your unit may OK.

[James W.]

Re: 1965 Fuel Sending Unit Test Help!

I also per Hinkley's test instructions, tested the voltage at the power wire to the fuel gauge and at the power wire at the sending unit. I read 11.85 volts in both places so I'm getting nearly the correct voltage (12) at both locations. Checked the wiring connections at the fire bulkhead connections, at the rear wiring harness connector and the dash harness connector and checked to be sure the main ground wire was tight at the cross bar. Everything was seated tightly and the ground screw was tight.

James

[Gary B.]

Re: 1965 Fuel Sending Unit Test Help!

Per Hinkley's instructions, I did that also. The readings were near 0 ohms when the float is in the raised position and almost 90 ohm when the float is pushed to the near the bottom of the tank. Again the opposite of what is written in Hinkley's test instructions.

James

[Mark M.]

Re: 1965 Fuel Sending Unit Test Help!

I checked a few good original and repros here with the meter on the S and ground terminals as you did and I too get similar readings. When on the S and I terminals the readings are correct for full and empty. If your sending unit won't read correctly on the S and I , you may have to pull the unit. Apparently your fuel gauge doesn't work. Where does the needle read ?

[James W.]

Re: 1965 Fuel Sending Unit Test Help!

Sending unit is still installed in the tank. I measured the resistance with the float at the top or up position and at the bottom or down position. Those are the readings those positions gave me.

James

[James W.]

Re: 1965 Fuel Sending Unit Test Help!

When the key is turned on, the fuel gauge reads 1/4 tank because that is the level of fuel in the tank. It will only read approximately 3/4 of a tank when the float is raised to the top and empty when the float is pushed to the bottom. When the key is off it stays at the 1/4 full reading.

James

I checked a few good original and repros here with the meter on the S and ground terminals as you did and I too get similar readings. When on the S and I terminals the readings are correct for full and empty. If your sending unit won't read correctly on the S and I , you may have to pull the unit. Apparently your fuel gauge doesn't work. Where does the needle read ?

[Mark M.]

Re: 1965 Fuel Sending Unit Test Help!

James is your sending unit the original? I have a test fixture here with a battery and a gauge. I placed an unrestored original 67 unit on it and it works most the time but often the gauge reads 3/4 when the float is all the way up as yours. The test fixture also helps to check the float swing ranger as some original tubes are bent inconsistently so tank levels will read differently. The original sender has a black wire that's in the variable resistor housing which gets brittle and stiff and may resist the float swing near the top but more likely the small wound wire that the point rides on is going bad in your sending unit. Try gently moving the float up and down a little at the top of it's range and the gauge may pop up to full. The tired 67 unit here does it.