Repairing 2 Alfetta gtv fuel senders - A DIY of sorts

[jazig.k]

Hi everyone. Thought I'd post up the repair of 2 non functional fuel level senders from a '76 GT I recently picked up and the '81 parts car we picked up last week. Maybe the info has been posted elsewhere but I didn't find anything searching myself so cracked into them, learning by doing.

So basically, all the sender is is a variable resistor with the float lifting the sensor pickup along the resistor wire wrapping. So i had in mind the wires would be broken with wear, and was just going to solder in 4 resistors to give 1/4 tank indications or something. Having never played with one, I expected the worst.

I tested both by hooking up the multimeter to the lead and the metal body to test resistance in Ohms. One wire is the fuel level, the other is the low level light. Or like my 2, they both do nothing regardless of float position.

Pulling them apart, I just cleaned up the contact surfaces of the ground with scotch brite pad and bent the contact pieces a little for better contact and then they tested perfectly.

So I'll try to post the photos and explain them as we go through them... Starting with the sender from the '76 GT.

The first is the tools I used. The Ohms is reading almost empty position, so ignore that. Took the photo after i did it all. Could swap scotchbrite for wet and dry, I just don't know where mine got to...

The second photo is the little metal tab to bend up with pliers, then a little plastic clip to press across with the greatest of care knowing if you hear it click, it'll be broken and that sound will resonate with you for weeks while you suck it up to buy a new one...

Relief. As you see it's still in one piece. Lift one side up and slide the other end across out of the slot.

The ground tab to polish, scuff, sand clean. I bent it back up a little to apply more pressure to the mating unit. It seemed a little low maybe. 

[jazig.k]

Inside the sender, the little dimple was black on mine, so clean that up. inside notice the coil/wire isn't even. Don't worry, it's supposed to be that way due to the float movement not being linear moving in an arc.

The next is the resistance measure at empty.

Then resistance measured at full.

For info sake, the fuel level warning light read 10 Ohms on this unit after being checked.

[jazig.k]

This following one was from the parts car, a 81' GTV.

Theres 3 taps folded and clamping this one together. Unfold them...

Inside you find this grounding loop thing... clean it up.

It touches this surface inside.  clean it up too.

Un interrupted view of the guts. A little different, but the same principle.

[jazig.k]

Again i couldn't help myself and bent the thing. Kinda. It wouldn't read smoothly after testing, and only the very tip makes contact, so I added some extra tension to it and tried to get it to touch in 2 spots which didn't really work but it tests consistently rather than intermittently. A ball of solder in hindsight might have been better, giving a larger contact patch?

Testing Ohms at empty (1K Ohms)

and full testing. Not zero but low anyway. I would hope I never run the tank to empty.


And that's it. Saved myself buying a new one for "no reason". All that's left is to replace the pick up filters, test the floats (submerge in water, gentle squeeze and watch for bubbles) and drop the fuel tanks off for acid washing before tank sealing and coatings. One thing to pay mind to is that the body of the sender needs to be earthed to the chassis in order to work... So keep that in mind if you ever coat a tank and the sender stops working.

[NSharpley]

Dynamite post !!

Where were you about 4 months ago when I was trying to get one of these working??

I found success with just replacing the unit for a working one, but still no low fuel light.

Will use your info and recondition a spare that I have ...

THANKS!

[bonno]

Thanks for sharing. With the age of these cars, replacement parts are becoming more and more difficult to purchase. DIY type presentations such as yours, are a good means of providing owners the know how to carry out repairs.

[carlo rossi]

yes very common they get a scum build up I think oxide actually quick clean will do trick most of the time
well done good thread

[jazig.k]

Thanks everyone.

Even the simple stuff is nice to have a little walkthrough for sometimes so you head into a job knowing what to expect.

In this case I think the OHMs readings of each unit at empty/full are good reference for future people too.
Also says to me the difference between the 2, that potentially they can't be mixed between early and late model gauges. That needs to be confirmed though...

The finding about grounding from sender to tank to chassis will be important too, as I should have another DIY for fuel tank coating and relining soon. So I'll need to include a reliable ground source.