gas gauge sending unit 330 GT 2+2

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GEODAVKY
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gas gauge sending unit 330 GT 2+2

Post by GEODAVKY »

The fuel gauge would work intermittently. If jiggled the connection at the sending unit on the gas tank it would usually start to work again, but now it won't work at all. If I have to remove the sending unit how is this done?
1967 330 GT 2+2 8767
George Davidson
Jumprun
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Re: gas gauge sending unit 330 GT 2+2

Post by Jumprun »

I cant say about the 2+2, but I had the same issue with the GTC. My sender simply had a poor connection to ground. The gtc has fiberglass covered gas tanks so there is a dedicated ground wire that is oddly run to the tail light housing for ground. I cleaned and tightened the connection and all is well, even the red low fuel warning light works.
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tyang
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Re: gas gauge sending unit 330 GT 2+2

Post by tyang »

GEODAVKY wrote: Sat May 30, 2020 12:32 pm The fuel gauge would work intermittently. If jiggled the connection at the sending unit on the gas tank it would usually start to work again, but now it won't work at all. If I have to remove the sending unit how is this done?
I would agree with Jumprun and check the ground to the fuel tank first. You can first try simply adding a ground with alligator clips to the fuel tank and see if anything changes.

To remove the fuel sender, you'll have to remove the rear seats and the back panel under the rear window. Under the panel you'll find a trap door that will allow access to the fuel sender. Mark the wires, secure them somehow to keep them from falling out of reach, and unbolt the fuel sender. The original screws holding the sender in place were flat head round head machine screws and very easy to strip. Carefully pull the sender unit out being careful not to bend the float arm on the internal baffles.

You can test the sender with a multi meter, or plug it back into the wiring harness and operate the float arm through its range to see if it operates the gauge. Don't forget to add a ground to the fuel sender while you're testing it because it won't work properly.

Good luck!

Tom
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Re: gas gauge sending unit 330 GT 2+2

Post by 330GT »

Jumprun wrote: Sun May 31, 2020 12:01 am I cant say about the 2+2, but I had the same issue with the GTC. My sender simply had a poor connection to ground. The gtc has fiberglass covered gas tanks so there is a dedicated ground wire that is oddly run to the tail light housing for ground. I cleaned and tightened the connection and all is well, even the red low fuel warning light works.
There is no explicit ground on the 330 2+2 fuel sender. It depends on ground from the screws holding the sender to the tank and then the 4 bolts that hold the tank to the chassis. Since those 4 bolts has rubber pads (14 and 15) on both side of the tabs on the tanks, the ground depends on a bolt touching a painted tab as it goes through and grounding through the head of the bolt on the chassis.
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Since your 330 is a series 2, you have limited access to the fuel sender through the access panel in the trunk. Adding a ground wire from one of the sender screws would provide a secure ground. Most certainly, a jumper wire would let you determine if it is a ground issue.
Regards, Kerry
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GEODAVKY
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Re: gas gauge sending unit 330 GT 2+2

Post by GEODAVKY »

I Ran a wire from the sender screws to ground, but that didn’t do anything. There’s continuity from the screws on the sender to ground. I removed the 2 wires to the sender. There’s 12v from the green wire to ground and some voltage from the other wire to ground. Unless I’m missing something it seems that sender has to come out and either fixed or replaced.
Thanks everybody for the help.
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Re: gas gauge sending unit 330 GT 2+2

Post by John Vardanian »

You might try removing the wires from the sending unit and measuring the resistance from the coil terminal to the chassis of the unit. Do you know how full your tank is? The E-F range of the coil is 20 to 100 ohms. If your coil is working you should get a number in between. Shake the car and see if the number fluctuates as the fuel sloshes.

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GEODAVKY
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Re: gas gauge sending unit 330 GT 2+2

Post by GEODAVKY »

Just filled the tank to see if that might be the problem, but it wasn’t. Not sure what you mean by the coil terminal?
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Re: gas gauge sending unit 330 GT 2+2

Post by tyang »

Hi George,

If you take one of the wires and give it ground, it will peg the gas gauge. 0 resistance on that wire gives you a full tank. The other wire is the low level warning light. It sounds like the sender inside the tank is not working right.

Tom
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Re: gas gauge sending unit 330 GT 2+2

Post by chris »

If you have the sender unit out you will see an internal coil of the sender. The arm of the swimmer has a contact touching this coil and by this the different touch points give different readings equaling resitance according to the fuel height in the tank.

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Re: gas gauge sending unit 330 GT 2+2

Post by John Vardanian »

George, there are two terminals on the sending unit. One goes to the gauge dial (brown wire, labeled "T"), the other goes to the gauge warning light (green wire, labeled "W"). Connect your ohmmeter from the "dial" terminal to the chassis of the sending unit. Swinging the float arm from one end to another should give you a range of 20 to 100 ohms. If you haven't taken the unit out of the tank, disconnect both wires then connect you ohmmeter and try the "sloshing" method I suggested earlier.

john
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Re: gas gauge sending unit 330 GT 2+2

Post by tyang »

John Vardanian wrote: Mon Jun 01, 2020 6:02 pm George, there are two terminals on the sending unit. One goes to the gauge dial (brown wire, labeled "T"), the other goes to the gauge warning light (green wire, labeled "W"). Connect your ohmmeter from the "dial" terminal to the chassis of the sending unit. Swinging the float arm from one end to another should give you a range of 20 to 100 ohms. If you haven't taken the unit out of the tank, disconnect both wires then connect you ohmmeter and try the "sloshing" method I suggested earlier.

john
George's sender may look different than yours John. I think by the 330GTs, they switched to a plastic bodied sender that sits immersed in the fuel. There's a plastic cap that needs to be removed to see the coil and you have to follow the wires up to the mounting plate to determine which is which. Same idea, but different look.

Tom
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Re: gas gauge sending unit 330 GT 2+2

Post by tim »

Greetings... The sender in my 330GT looks like the one pictured. The brass float on mine had leaked and I sourced a replacement from an Alfa
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Re: gas gauge sending unit 330 GT 2+2

Post by tyang »

tim wrote: Tue Jun 02, 2020 9:47 am Greetings... The sender in my 330GT looks like the one pictured. The brass float on mine had leaked and I sourced a replacement from an Alfa
Hi Tim,

The SI 330s and my 330 America used a similar set up that John pictured with a longer arm, but some where in the run of 330s, they changed to the plastic bodied floats. 275GTBs had the plastic ones too.

They make new floats that are a little more resistant to the new fuel, but I like the brass ones provided the solder hold up!

Tom
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GEODAVKY
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Re: gas gauge sending unit 330 GT 2+2

Post by GEODAVKY »

John Vardanian wrote: Mon Jun 01, 2020 6:02 pm George, there are two terminals on the sending unit. One goes to the gauge dial (brown wire, labeled "T"), the other goes to the gauge warning light (green wire, labeled "W"). Connect your ohmmeter from the "dial" terminal to the chassis of the sending unit. Swinging the float arm from one end to another should give you a range of 20 to 100 ohms. If you haven't taken the unit out of the tank, disconnect both wires then connect you ohmmeter and try the "sloshing" method I suggested earlier.

john
The warning side gives an ohms reading, but the gauge side does not register. Guess this means a bad sender?
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Re: gas gauge sending unit 330 GT 2+2

Post by John Vardanian »

George, I don't know what to say. if there is no continuity between the coil terminal and the chassis of the sender then that means the coil is open. You may want to check for these: Is the coil unraveled? Is the coil discolored like it's overheated due to a short? Is there moisture oxidation in the coil housing? If it looks clean and healthy then look for a broken wire/connection. Good luck.

john
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