Electrical How to test a fuel tank sending unit

limp · Apr 3, 2024

Starting a new thread here off of my Fuel line routing post....

Easy question is can I test for continuity between the two posts on the fuel tank sender? Tested with my battery powered probe and I get nothing..
Remember this is an 83, so only two wires to the sending unit with a fuel pump on the engine...

Elec trouble shooting manual says to check for ground, Good ground..
Check for power to the sending unit with the key on... Light blinks uniformly.....
When I put power on one side of the sending unit I get nothing out of the other....
Would this be a bad sending unit or am I doing this wrong.. Sending unit is still in the tank....

All gauges work fine except the fuel gauge...

General karthief · Apr 3, 2024

I would get a couple test wires to extend from the plug to the sender then tip the tank on it's side so the float moves, turn key to on and wait for flames to shoot out the hole in the tank
if your not sure the gauge works you can test the gauge with a 9 volt battery.

limp · Apr 3, 2024

General karthief said:
I would get a couple test wires to extend from the plug to the sender then tip the tank on it's side so the float moves, turn key to on and wait for flames to shoot out the hole in the tank
if your not sure the gauge works you can test the gauge with a 9 volt battery.

I have the tank out and everything checks out so far.. Thats why I asked if there should be continuity between the two contacts on the sender... If its yes, I have a bad sender and I will get another...
Just asking if I am testing the sender correctly.

General karthief · Apr 3, 2024

limp said:
I have the tank out and everything checks out so far.. Thats why I asked if there should be continuity between the two contacts on the sender... If its yes, I have a bad sender and I will get another...
Just asking if I am testing the sender correctly.

i don't know all that continuity/electrical stuff. I can test for power, ground and how many volts it has, remember: shade tree sht, I'm just lucky enough to have a really nice garage thanks to Brand X.
Oh, and IF I have a tool that works it's by accident.

Mcmahst · Apr 3, 2024

I believe on a 83, the two posts are sending unit and low fuel warning. Both, individually, should have continuity to ground. The wiring connector to the sender should have two wires. From their color code, you should be able to determine which one is the sending unit. That wire should be Yellow with White tracer. The ground for both circuits are the chassis; can someone verify that? I know at some point, Fird ran a ground to that connector.

AeroCoupe · Apr 3, 2024

You should have resistance so ohms. On the 1983 sending units it should read 73 ohms empty and 10 ohms full. When you sweep the sending unit from full to empty or visa versa the change in the ohms reading should be smooth.

limp · Apr 4, 2024

I do not have an OHMS meter... There are two connections to the sender.. Intermittent power that comes from the IVR ( Instrument Voltage Regulator) goes to one and the other is a ground... The low fuel warning is on the same circuit ( although I think that was in the console which my car did not come with)...
So using my battery operated test probe, that only has a light, on the sender connections I would think that it would light up even if faintly...
No light at all.....

After watching a couple of you tubes I am going to remove the sender from the tank and see if I can't fix it, or at least hook it up to the car and see if it moves my fuel gauge moving the float..

limp · Apr 4, 2024

Mcmahst said:
I believe on a 83, the two posts are sending unit and low fuel warning. Both, individually, should have continuity to ground. The wiring connector to the sender should have two wires. From their color code, you should be able to determine which one is the sending unit. That wire should be Yellow with White tracer. The ground for both circuits are the chassis; can someone verify that? I know at some point, Fird ran a ground to that connector.

If you read my first post, using my Electric and vacuum trouble shooting manual, I had a good ground and the IVR seemed to be working correctly sending an intermittent pulse of electricity...

By using my test probe ( lighted probe) to see if power ran from one connection to the other on the sender, I was just trying to simply determine if my sender is bad...

AeroCoupe · Apr 4, 2024

Get a digital volt meter (DVM) and do the test. This is one of those things that became a necessary tool in the tool box back in the 90’s. It will save you a lot of time and it can also help you do other cool 90’s stuff like voltage drop tests, locate shorted circuits, check voltages, etc. You know I’m busting your balls Limp but you should really get one.

limp · Apr 4, 2024

AeroCoupe said:
Get a digital volt meter (DVM) and do the test. This is one of those things that became a necessary tool in the tool box back in the 90’s. It will save you a lot of time and it can also help you do other cool 90’s stuff like voltage drop tests, locate shorted circuits, check voltages, etc. You know I’m busting your balls Limp but you should really get one.

Trust me its been on my list.. It would take time away from my projects ( that I don't have any extra of) to learn how to use it...... LOL
Any recommendations on a good brand or model? I dont mind paying a bit more for a better unit...

limp · Apr 4, 2024

BUT, back to old school here....
See the pic, if I get NO light on my battery powered probe doing this, doesn't this mean I have a dead sender??
This sender sat in half a tank of California fuel for over 20 years.. Amazing condition, the tank is just as clean if not cleaner...

General karthief · Apr 4, 2024

Try lifting the float, although I think it won't work, it works off resistance so
If you can hook up the battery in the car then plug the sender in an lift the float.

AeroCoupe · Apr 4, 2024

Man I’m still using an old Radio Shack unit but we only use Fluke at work. I have some Klein tools and they are good quality so I’d think that would be a good brand.

Amazon.com

manicmechanic007 · Apr 6, 2024

I have 5 or more DVOMs
The 3 dollar harbor freight ones (the ones they used to give away) work fine for voltage and resistance checks IMO
I think you have an open sender Limp
The sender wire should have 73 ohms empty and 10 ohms full
Used to keep a few resistors around to check gauges
They switched the senders resistance specs in 86 or 87 IIRR

limp · Apr 6, 2024

Going to splurge on a tester next tuesday... I guess I need to get into the " 90's"......
I spent all of my childrens inheritance this month already so I have to wait for Next months inheritance to spend.....
Going down a different " street " now with the Hot Wire problem before I can come back to the sender... When I get my tester I will OHM check it..
1200 rds of ammo and a new vise put me overbudget this month...

General karthief · Apr 6, 2024

You may need more than 1200 rounds to kill that vice, they don't move too fast but are hard to kill

limp · Apr 6, 2024

General karthief said:
You may need more than 1200 rounds to kill that vice, they don't move too fast but are hard to kill

Two purchases, seperate agendas for each....

manicmechanic007 · Apr 7, 2024

Everybody needs a good vise
That one looks nice
Enjoy the bullets
I got a gross of P9s and P38s. to play with

limp · Apr 7, 2024

Tested my fuel sender today with an ohm meter... Its DOA....
Thanks for all the help everyone...

AeroCoupe · Apr 7, 2024

Limp is in the 90’s hizzouse! Welcome to the world of DVM. Next up is a smart phone…

Glad you got it figured out man!

Electrical How to test a fuel tank sending unit

limp

wrap a little cheese around it and its a done

General karthief

wonder how much it would cost to ship you a pair

limp

wrap a little cheese around it and its a done

General karthief

wonder how much it would cost to ship you a pair

Mcmahst

AeroCoupe

lube between the nut and the face. I know my lubes

limp

wrap a little cheese around it and its a done

limp

wrap a little cheese around it and its a done

AeroCoupe

lube between the nut and the face. I know my lubes

limp

wrap a little cheese around it and its a done

limp

wrap a little cheese around it and its a done

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

lube between the nut and the face. I know my lubes

manicmechanic007

limp

wrap a little cheese around it and its a done

General karthief

wonder how much it would cost to ship you a pair

limp

wrap a little cheese around it and its a done

manicmechanic007

limp

wrap a little cheese around it and its a done

AeroCoupe

lube between the nut and the face. I know my lubes

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Electrical How to test a fuel tank sending unit

wrap a little cheese around it and its a done

wonder how much it would cost to ship you a pair

wrap a little cheese around it and its a done

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

wrap a little cheese around it and its a done

wrap a little cheese around it and its a done

lube between the nut and the face. I know my lubes

wrap a little cheese around it and its a done

wrap a little cheese around it and its a done

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

wrap a little cheese around it and its a done

wonder how much it would cost to ship you a pair

wrap a little cheese around it and its a done

wrap a little cheese around it and its a done

lube between the nut and the face. I know my lubes

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