Gas tank sending unit not working correctly

[JBtwist]

I've pulled the sending unit out and put an Ohm meter on it - it starts around 28 ohms and as you raise the float, decreases steadily, but when it reaches near the top it looses a reading sparaticlly and when completely full, gives me no reading.

I've taken it apart and it appears to be a serviceable replacement part that uses magnetic positioning to move the needle and change the reading.

I've been able to find this:

https://www.walmart.com/ip/Moeller-...75035&wl11=online&wl12=37578334&wl13=&veh=sem

which appears as though it would fit right in (same form factor)...but it doesn't have leads to send to the gauge on the dash.

Do I just need to buy a brand new sending unit? I've put a magnet on the float portion and it turns the magnet as I lift the float, so I believe the issue is isolated to the meter/sending portion of the float.

 

[alldodge]

Yes, you need a new sender

The North America sender for gauges is 240 to 33 ohms (Empty to Full), so your sender is bad. It can be replaced with the same type or tube.

 

[JBtwist]

Thank you for the reply. I'm wondering if I can just replace this exact piece - it seems to be where the issue is.

 

[alldodge]

Guess I missed the issue for you measuring the gauge with an ohm meter. It appears you have a mechanical gauge and sender so there would be no electrical part. If this is the case then replacing just the gauge part should fix the issue

 

[JBtwist]

The electrical is grounded from the mounting plate, the ohms are fed from a screw on top of the meter...see the picture. That is a threaded post for a wirenut.

 

[alldodge]

Guess I'll just take your word for it, because I don't see how it would be electrical. Your sender bottom appears that the lower plate (Blue arrow) would move with the float going up/down. The gauge pin (yellow arrow) looks like it would cause the gauge to move.

Your walmart link was for a mechanical gauge

Hope another can assist further

 

[JBtwist]

no, it's magnetic. Blue arrow has a magnet that raises and lowers. That in turn, spins a magnet in the separated part which is essentially a compass. The yellow arrow points to the electrical lead that gives you ohms readings (240-33 in this case).

 

[alldodge]

OK, it is a mechanical gauge
https://www.ebay.com/itm/Moeller-03...el-Gauge-For-12-Tank-Depth-1974-/361995688680

 

[JBtwist]

Hate to keep the thread going but it's mechanical (sight read) as well as electronic, it has ground and positive leads to send to a dash gauge.

The link you provided is the mechanical ONLY.