Fuel sending unit 69 RR 383

[‘69_Sunfire_RR]

All:
A few questions about your experience with aftermarket fuel senders.

Purchased my car restored. New sender and new gauge (in original gauge cluster). Also have a new voltage reg. On empty, gauge reads 3/4. Full it’s off the charts. I changed senders to a new aftermarket version. No change. After that I’ve added resistance in line with the gauge lead on the sender. I added about 58 ohms so far through testing etc. now on empty I’m at 1/4 and full it’s on full. I cannot get it dialed in closer than this. Adding more resistance inline only pulls the needle up on full ( so full is now above empty) etc. just wondering if you all have some advice. I thought of purchasing another new unit but this time from Mancini. That would be three new senders here. Anyone purchased any that were absolutely accurate out of the box? If so, what manufacturer? Thank you all in advance.

 

[quikbird]

this is a common problem lately. double check your new gauge and sender are set up for the same range on the ohms, some are 70/30, others are 90/10, and never the two will mix and play nice together. that said there is a company that makes a piece that fits in the wire and can fine tune the reading, but with adding the resistance you may be doing what it does.

 

[69hemibeep]

How many ohms is the sender at empty? I don't know of any good ones.

 

[Russ69Runner]

Not to say I know any thing better but some say they have to bend the float to get it to read rite. These thing's are really getting to be a bad rep. Don't know if classic sell's any thing better or did you try AMD.

 

[Roadcuda]

I put one of these in my car. It's easy to install. It splices into the wire from the sender to the gauge and a Poss, and neg wires for power. I placed mine just above the left kick panel which is where the wire to the gauge comes up from the tank. You have to adjust the meter to the sending unit so I would suggest doing that with the sending unit out of the tank. I did it with it in the tank and I still was able to get it real close. The directions were pretty clear.

https://technoversions.com/MeterMatchHome.html

 

[‘69_Sunfire_RR]

Thank you all for the advice and detail here! My sender is 70/30. I tried everything to get things to play well so I need to check resistance at the gauge. I also tried to bend the float arm to get it off the bottom of the tank to get to true empty on the gauge. This didn’t help. There are two stops on the sender for the float arm. I also bent one of those down to allow the float arm to go farther down. This also to get to true empty on the gauge. No go. The problem with going past the stop is that the sweeper inside the sender will bend as it goes past the resistor. So I had to disassemble the sender and fix the sweeper. Not advisable, gents. Had to use my wire feed welder to put that back together... these senders are junk. I like this meter match device though! Thank you for the suggestion! I think I’ll give this a try as well. Thank you all again! This is the last step for me on my journey to 100% restored. Cheers!

 

[Big John]

Adding resistance isn't what you want to do to correct the gauge across the scale. It moves your "zero" point but not the "scale".

The Meter Match is the way to go.

Here's what I did with my 300: https://www.forcbodiesonly.com/mopar-forum/threads/gas-gauge-fix.32116/

A couple things... First, the sender needs a good ground. There should be a clip that grounds the sender to the gas line, but I've found that it's better to add a wire (see pics in the link) that gives a good ground to the frame. Next, ALL the wiring has to be good, ALL the connections clean. The voltage limiter needs to be putting out 5 volts (better to replace with a new electronic unit).

 

[‘69_Sunfire_RR]

Adding resistance isn't what you want to do to correct the gauge across the scale. It moves your "zero" point but not the "scale".

The Meter Match is the way to go.

Here's what I did with my 300: https://www.forcbodiesonly.com/mopar-forum/threads/gas-gauge-fix.32116/

A couple things... First, the sender needs a good ground. There should be a clip that grounds the sender to the gas line, but I've found that it's better to add a wire (see pics in the link) that gives a good ground to the frame. Next, ALL the wiring has to be good, ALL the connections clean. The voltage limiter needs to be putting out 5 volts (better to replace with a new electronic unit).

Hey thank you very much! Agreed. It could be as simple as the ground though it seemed well grounded. I’ll add the ground strap to the fuel line/sender and then to the frame. All connections are very clean, I’m using the newer electronic version of the V limiter. Thank you for sharing the link to what you’ve done. Very helpful and I’ll take a look! Thank you very much!

 

[dmartin]

Hey thank you very much! Agreed. It could be as simple as the ground though it seemed well grounded. I’ll add the ground strap to the fuel line/sender and then to the frame. All connections are very clean, I’m using the newer electronic version of the V limiter. Thank you for sharing the link to what you’ve done. Very helpful and I’ll take a look! Thank you very much!

Clean the line close to the sending unit make sure ground strap is secured good and check the connections on your gas gauge and it should read close

 

[Big John]

Clean the line close to the sending unit make sure ground strap is secured good and check the connections on your gas gauge and it should read close

Here's the problem with that... It grounds to the fuel line, but the fuel line itself isn't necessarily a good ground. In theory, the line grounds to the body through the clips attaching the line to the frame, but it doesn't always work out. Paint... rust... dirt... whatever...

 

[‘69_Sunfire_RR]

Same thoughts here. I may ground it to the line but I would also add another ground to a known good ground point.

 

[Russ69Runner]

Yes every one thinks I must be the hot wire that has the problem. But with DC it is important to have a real good ground.

 

[Rich B]

Had the problem with my ‘79 ‘Lil Red Express. Gauge would always show empty with fuel in tank and ran forever on full. Bending the float rod worked; when tank read empty better believe it, on the money. Also had the bond wire integral with sender assembly. Seems it was even a green wire, maybe not.

If not working by calibration that way, make sure gas gauge is zeroed in at dash. Could be done with a pointer set screw, if it’s there (can’t recall) or even gently bend arm. Meters all exposed and part of main circuit board without cluster crystal, not individual sealed. Also may need cleaning, maybe dust ball interfering with movement.

Keep positive wire away from sender circuit of coarse, won’t mix well with fuel. Same difference with the analog Simpson multi-meters, same adjustment with cal potentiometer and meter zero-in screw. Today it’s digital Flukes, ohm reading can tell you if high or intermittent resistance is present.

Just my experience on that, not trying to sharpshoot other remedies.