Replacing Fuel Sending Unit Float

[chaseincats]

11 minutes ago, grannyknot said:

I can't help you with your bouncing needle except to say make sure all electrical connections between the sender and gauge are clean. Also, the wiper arm should touch the wound wire, the wire is one continuous strand from end to end so as the wiper moves up and down so does the resistance and that is what move the needle.

Hmmmm, check to see if there is anything stuck on the wire that might be preventing contact with the wiper at one point.

 

Gotcha.

I remember that my wiper arm also has a red liquid between the wiper arm contact (the part of the wiper arm that touches the metal wire winding) and the wire winding.  I always assumed that was some sort of lubricant - should that be there or should I wipe it off?

[zKars]

I have a few old 240 senders, I could send you one and you could use it's float. I'd splice the metal rod close to the float, don't try to "remove" the float per sey. I'll see if the 240/280 floats are the same size. 

[grannyknot]

8 hours ago, chaseincats said:

Gotcha.

I remember that my wiper arm also has a red liquid between the wiper arm contact (the part of the wiper arm that touches the metal wire winding) and the wire winding.  I always assumed that was some sort of lubricant - should that be there or should I wipe it off?

Lubricant is okay although the gas will wash it off pretty quickly, I just thought that if the needle was jumping around that there might be something on the wire that momentarily broke the contact.

[chaseincats]

36 minutes ago, grannyknot said:

Lubricant is okay although the gas will wash it off pretty quickly, I just thought that if the needle was jumping around that there might be something on the wire that momentarily broke the contact.

Gotcha.  I'll wipe off the red stuff and bend the wiper arm so its touching the coil and not hovering above it - then see if that fixes the accuracy issue.

@zKars I'll take the sender out and pop it in a bucket to test the float - I may take you up on that offer depending on what happens - thanks so much for offering

Edited January 29, 2020 by chaseincats

[grannyknot]

58 minutes ago, chaseincats said:

and bend the wiper arm so its touching the coil and not hovering above it

Wait, the wiper has not been touching the wound wire?  If that's the case then there's the answer to your problem, no wonder the needle is all over the place.

[gwri8]

I've been chasing electrical in my 77' for the last three month's .  A floating/misreading fuel gauge was one of those problems. I know I checked and cleaned the connections and wiring from the gauge to the sender at least three or four times.  Today, just by chance, I noticed that yellow/green mate lock connector to the fuel sender was slightly receded in the connector housing not making a full contact with the male pin when they were pushed together. I've repaired that and will double check it again tomorrow if I can get my car out.  So, when you inspect the connections, look really close.?

[chaseincats]

48 minutes ago, grannyknot said:

Wait, the wiper has not been touching the wound wire?  If that's the case then there's the answer to your problem, no wonder the needle is all over the place.

I believe its not firmly pressed up against it.  When I get back in town I'll pop it out and report back

[chaseincats]

Update: so there wasn't any red stuff on wiper arm (not sure where I came up with that) but the wiper arm wasn't 100% pressed up against it.  I heavily bent the arm so that it makes good contact with the coil wire now but that didn't seem to be it.

I grounded out the connector to the gauge to see if it would peg as a full which would confirm the wiring and gauge were working and they are, which is good.

I started jiggling stuff on the sender unit and the gauge started dying then coming back to life so it was an electrical connection issue between the harness and unit coil.  What it ended up being (we think) was the rivet connector between the yellow power wire (from the harness) and the wire for the coil/wiper arm on the sender unit.  I could spin the rivet inside the housing meaning there was a poor contact between the yellow power wire and the sender unit's coil wire.

We put some solder on there to bridge the rivet with the wire's connector and it may have done the trick.

If it still isnt working properly, then we're out of ideas - will update you guys later on.

 

EDIT: I forgot to mention, I tested the float in a bucket of water and it worked with no problems

Edited February 8, 2020 by chaseincats