Fuel Sender

[Bones Jackson]

Can somebody tell me how the sender is grounded in a 68 coronet? Reason I ask is I and getting 125 ohms when I test with a meter. I am connecting one lead to the stud on the sender and the other to the chassis. Am I doing something wrong? Or do I not have the tank or sender grounded.

 

[miller]

The stud on the sender unit is where the gauge wire fastens. You should use red ohms lead on it. Black, of course goes to ground.

To answer your question on ground...the 'body' of the sending unit is the start of ground. But, ground must be completed to the car's body/frame. Where the actual fuel line (steel) meets the sending unit, and joins via a short fuel hose, there should be a metal grounding strap, that snaps onto the fuel sender outlet. That strap 'spans' across that short rubber hose, snaps onto the steel fuel line, and completes that connection of ground.
Fuel line running the body frame snaps into place using metal clips. Those metal clips, on both the fuel line, into locating holes in the car's frame, completes the ground connection.

If your NOT using steel fuel line, such as stainless steel, need separate grounding done, from sending unit body to frame.

 

[Bones Jackson]

OK. I'm using a sump with AN lines so that tells me no ground. Makes sense. I'll try and create a ground from the outlet line on the sender and run it to the frame and see what happens.

 

[Beekeeper]

To test the sender put one lead on the insulated stud and the other on the metal part of the sender be sure you have a clean connection.
.

 

[miller]

OK. I'm using a sump with AN lines so that tells me no ground. Makes sense. I'll try and create a ground from the outlet line on the sender and run it to the frame and see what happens.

Yeah, probably your best bet. Might think #12 or #10 strip of new wire, one end maybe clamped to sender's outlet, run your ground wire so it won't rub on anything, and directly to the frame. Other's have simply ran wire to the body somewhere. Gauge itself is grounded under the dash.
Tank itself probably won't be grounded to body, not if it has a pad between 'em.

 

[Bones Jackson]

So I grounded the senders outlet to the frame and checked ohms. I'm getting 105 and it will fluctuate if I rock the car. I wonder if someone put an aftermarket sender in it considering the high ohms. However it looks like a regular replacement stock sender.

 

[miller]

Always possible. Might check this...pull the (gauge)wire from the sender stud, and check ohms from the stud to the sender's body. Also check ohms across the ground wire you added. That one should be near 0 ohms, or not far off. If not, ground might not be good enough...needs clean metal on both ends.
Of course, sender's gauge wire stud should be 73 - 10 ohms, or in that area, depending on your amount of gas in tank.

 

[Bones Jackson]

OK I'll try it again tonight. I've gone from the stud to the sender body before and have gotten values in the 100's. I'm not sure how much fuel is in the tank though, most likely less than half. My goal here is to find out what Autometer gauge to buy since I'm replacing the OE stuff.

 

[miller]

Yeah, I'm in the same boat. Planning to use AutoMeter across the board. Their fuel gauges for Mopar are supposed to be calibrated for 10 (full) to 73ish (empty), to work with the sending unit.

Just curious what ohms do you get from ground to ground? That part okay?
Anyway, I've got four sending units, one an after-market piece. The three others, stock units each read at, or over 100 ohms. (Can't figure I'd be that lucky??) Just playing with 'em, to try to get one back into the right range.

Not really sure what to tell you on the ohms your getting. But, learning real quick most, if not all after-market ones are junk. Heck, got a brandy new tank, but refuse to mount it, until I find a good sender.

 

[miller]

Don't know if this will help anybody, but here's what I found on one of my stock fuel senders.

The stud, where the fuel gauge wire connects, goes through the base plate for the sender, attached to a metal 'strap' to the sensor. All three stock unit I've gotten, on empty read over 100 ohms. Only looking at trying one unit, others having problems with rust, worn or broken parts, etc.
Opened the one unit, to check things, try adjusting it. It was reading 105-30. Used a small clamp to hold it together, while re-testing. No reading. Hmm. Tried ground directly to that metal strap. 81-11.2 ohms.

Bad connection between stud and strap, or in my case, wound up no connection. Going to pull the stud, replace it with bolt and nuts, using original insulators. Should get connection back, with good numbers.