67 Fuel Gauge Sending Unit

[Steven C.]

[Phil P.]

remove and clean sender soak in oil before install *NM*

[Jack H.]

From the service manual...

The troubleshooting by symptom table for the gas gauge has only a single entry for 'Pointer does not go above 1/2 position'. The corresponding troubleshooting entry is to check and repair the defective ground wire at the gas tank...

[Gerard F.]

Re: 67 Fuel Gauge Sending Unit

Steve,

Try cleaning all of the connections at the sender (disconnect battery). Then reconnect and push the float up and down with your ignition on.

Jerry Fuccillo
#42179

[Steven C.]

[Gerard F.]

Re: 67 Fuel Gauge Sending Unit

Steve,

Try moving the float back, then up and down, see if that works. If not, then forward, then up and down. If that doesn't work then I think you are going to have to pull the sender, clean off the point contact and the variable resistor in the housing. If it is your original, best guess is that the resistor is dirty, or one of the contacts is broken. Braking over the years would tend to move the float forward.

Jerry Fuccillo

[Joe R.]

Re: 67 Fuel Gauge Sending Unit

The midyear sender/gauge is difficult to troubleshoot because it is not just a simple resistance to ground. John Hinckley published a very nice step-by-step troubleshooting article in Corvette Enthusiast a few years ago. Maybe he can send you a soft copy. If not, I can send you a photocopy.

[Steven C.]

Re: 67 Fuel Gauge Sending Unit

Jerry, I will try to move it forward and back.

Joe, that article sounds like what I need. Is that something that can be emailed? If so, let me know and I will forward my address.

Now I need to siphon out a full tank of gas.

Thanks all.

[Richard S.]

Re: 67 Fuel Gauge Sending Unit

Steve,

I am experiencing the same problem you have. Can you post what you learn.....thanks,

Rick.

[Joep F.]

Re: 67 Fuel Gauge Sending Unit

Had the same problem not long ago. Turned out that the rheostat in the sending unit burned out half way. Had to replace the whole sender.

[Gerard F.]

Re: 67 Fuel Gauge Sending Unit

Steve,

Before you pull it from the tank, there is an easy way to test the sender on the car. Get a good digital ohm meter (9V). Pull the two colored leads from the sender and attach the ohmmeter to the contacts. With the float in the up position full, the meter should read around 90 ohms, with the float in the down position the meter should read around zero ohms.

If you get the above readings the sender is OK, and your problem is between the sender and the gage, or the gage. Remember to always disconnect the battery whenever you are playing with electrical, you never know.

If you are getting erratic ohm readings, then pull the sender. Take a look at this post from the archives (where I fixed the insulation within the resistor housing):

https://www.ncrs.org/forum/archive29.cgi?review=261361

There is also lots of other threads in the archives on the C2 fuel sender.

If you have to replace the sender, don't get one of those cheap foreign jobbers ($60 to $80). Get the GM replacement which I think is over $200. I tried one of those foreign jobbers and it lasted about 6 months.

Jerry Fuccillo
#42179

PS Check the O-ring gasket before you put it back on, maybe have a new one on hand, and that special tool for removing and installing the sender.

[John H.]

Re: 67 Fuel Gauge Sending Unit

The check Jerry noted verifies one side of the voltage divider circuit. To check the other side, connect the meter to the gauge pin terminal (marked "S" on original senders) and to the ground spade on the sender, and repeat the float arm movement. You should see the reverse of the first test, with zero ohms with the float all the way up (full), and 90 ohms with the float all the way down (empty). You can use this same routine (what Jerry posted plus this one) to verify the accuracy of a new sender on the bench before you install it.

Send me your e-mail address and I'll send you a text-only copy of the full article, which covers diagnosis of the entire system, including the gauge.

[Joe R.]

Re: 67 Fuel Gauge Sending Unit

Hi Steve:

It looks like John has offered to email you the text of his article. If you want a hard copy of the article, email me your address offline and I will send it to you.

[Steven C.]

Re: 67 Fuel Gauge Sending Unit

Joe, John forwared me the article. Thanks for the offer.