Fuel Sender Grounding Advice

[Carlwalski]

Hey folks, I have a Dakota Digital RTX gauge set in my 70 RT, I love it but my fuel gauge is inconsistent. When I fill it up, it shows maybe 88-92% (never really full), I drive 20 mins and it will fluctuate down then up 5-10%, not too bad but not correct either. And when it hits 50% or 1/2, it seems to go WAY too fast vs. the first half. Its just not reading right lol, that I know.

I believe its the ground, gauges all work great in the cluster so I don’t think its JUST the 1 fuel gauge acting up. I have an in tank pump for my EFI system so cut and welded closed the old pickup and return and use it solely for the sender only.

Question: is my current ground (pics attached) a bad setup? I think its too small a gauge? Not enough metal maybe? Tested sender on bench and its perfect ohms. I thought about putting a metal ground crimped on to one of the old sender “nubs” and running that to the chassis?? I can’t use a standard sender ground strap so any ideas that will make the connection SOLID?

Thanks!

 

[EW1BH27]

I once ran a wire to the frame rail BUT yours looks good with that bare part cleaned off.
I've been a big fan an added wire hack.

 

[Challenger RTA]

putting a metal ground crimped on to one of the old sender “nubs”

I would have to agree. One would think the lock ring would do it. But it is not part of the sending unit it's self. I think you figured it out. You might just have move or jump over to the ground you put there. Now you have to follow through. Let us know it might help someone else later. Thanks for posting it.

 

[Carlwalski]

I once ran a wire to the frame rail BUT yours looks good with that bare part cleaned off.
I've been a big fan an added wire hack.



View attachment 137808

Thank and very interesting. My sender itself on the bench reads true but I like what you did. Not a bad extra piece of reassurance.

 

[Carlwalski]

I would have to agree. One would think the lock ring would do it. But it is not part of the sending unit it's self. I think you figured it out. You might just have move or jump over to the ground you put there. Now you have to follow through. Let us know it might help someone else later. Thanks for posting it.

Thank you Sir. Im thinking of removing the current ground altogether and going larger from “nub” to steel. Is there such a thing as too think or too much ground?

 

[Carlwalski]

Maybe something universal like this? Just have to figure out how to secure it on the “nub” with full contact all the time.

 

[Challenger RTA]

too much ground?

No. To less of a ground, yes. Depending on the load.

 

[Challenger RTA]

Stainless would be a good idea. I don't know if this is.

https://www.amazon.com/dp/B007NR2MCC?tag=bravesoftwa04-20&linkCode=osi&th=1&psc=1&language=en_US

 

[Challenger RTA]

Stainless would be a good idea.

Now you got me thinking to change mine or add. I used the original ground strap and soldered a bare piece of 12Ga to it.

 

[Carlwalski]

Now you got me thinking to change mine or add. I used the original ground strap and soldered a bare piece of 12Ga to it.

Always like that on these forums! They say “a hotrod is never truly finished”.

Thanks for the help. That strap you posted looks good, it would slid over the half nipple but securing it in place might be difficult.

In this one below, looks like they tucked the “material” portion of the strap and clamped it down? Shouldn’t be hard getting a solid ground, having it STAY connected and not work itself free or loose causing inconsistent or no ground at all is probably the only thing now.

Shouldn’t be hard though. Just want it tidy and solid.

 

[Challenger RTA]

securing it in place might be difficult.

Drill a hole or use a self tapping screw through it as a clamp? Or as above, looks like they used another clamp.

 

[Challenger RTA]

The ground strap I just happen to have. It had a Chrysler tag on it. So I felt it was ok to put on. There can be an issue with mounting bolt for ground and coming loose. I was having problems from the carb and ignition from sitting over the winter. That's where this started from. I had a an electronic distributor and ECM and stuck it all on. It fix it. There was a dual point in it that have never been touched. Other points and condenser. Didn't have a new cap and rotor on hand. Took it out so I can work on it. As far as the bolts hole I fixed that too. Never mind the wiring. Something else going on there in the cowl.\
I post this elsewhere. I wanted to show the ground strap.

Nut-Insert Nutsert Rivnut​

 

[Carlwalski]

The ground strap I just happen to have. It had a Chrysler tag on it. So I felt it was ok to put on. There can be an issue with mounting bolt for ground and coming loose. I was having problems from the carb and ignition from sitting over the winter. That's where this started from. I had a an electronic distributor and ECM and stuck it all on. It fix it. There was a dual point in it that have never been touched. Other points and condenser. Didn't have a new cap and rotor on hand. Took it out so I can work on it. As far as the bolts hole I fixed that too. Never mind the wiring. Something else going on there in the cowl.\
I post this elsewhere. I wanted to show the ground strap.

Nut-Insert Nutsert Rivnut​

View attachment 137816

View attachment 137819

View attachment 137820

I see, I like your work and attention to detail and solving issues!

 

[Challenger RTA]

I see, I like your work and attention to detail and solving issues!

The devil is always in the details.

 

[DaveBob]

Hey folks, I have a Dakota Digital RTX gauge set in my 70 RT, I love it but my fuel gauge is inconsistent. When I fill it up, it shows maybe 88-92% (never really full), I drive 20 mins and it will fluctuate down then up 5-10%, not too bad but not correct either. And when it hits 50% or 1/2, it seems to go WAY too fast vs. the first half. Its just not reading right lol, that I know.

I believe its the ground, gauges all work great in the cluster so I don’t think its JUST the 1 fuel gauge acting up. I have an in tank pump for my EFI system so cut and welded closed the old pickup and return and use it solely for the sender only.

Question: is my current ground (pics attached) a bad setup? I think its too small a gauge? Not enough metal maybe? Tested sender on bench and its perfect ohms. I thought about putting a metal ground crimped on to one of the old sender “nubs” and running that to the chassis?? I can’t use a standard sender ground strap so any ideas that will make the connection SOLID?

Thanks!

View attachment 137792

View attachment 137793

View attachment 137794

View attachment 137795

I ran a 16 gauge wire from the sending unit to the under dash location where I mounted my ignition box. The ignition box mounting location is grounded to the back of the engine with a 10 gauge wire. I use the same grounding location for other gauges and stereo. Originally, I created the ignition box mounting plate, complete with machine threads for easy ignition box removal and replacement, because I wanted to eliminate clutter in the engine compartment, and to hide the box because electronic ignition was not available on a 70 model. When I installed Dakota Digital gauges, it was a convenient place to get the best grounding.

 

[Olacmot]

I have the VHX setup for my gauges. I looked at the RTX manual and it looks pretty close to the VHX setup so I hope this helps, as I had a similar issue.

First, with your key on, what’s the voltage at the sending unit connector, with it disconnected? I was getting intermittent voltage, and found a loose female terminal in the connector behind the drivers side kick panel. It will be the blue wire there, same color as the wire to the sending unit. If the voltage is low or inconsistent, it might be worth checking if that connector is clean and tight. Same with connections behind the dash.

Second, how did you set up the RTX fuel sender? I did the “manual adj” procedure (VHX setup calls this “custom” if anyone with VHX is reading this). If there are ranges on your gauge where it seems to consistently drain quickly, maybe the ohms range of how the gauges are programmed doesn’t match the ohms of the sending unit. Doing the “manual adj” should ensure everything matches. Pulling the sending unit out and doing this procedure worked pretty close for me. If voltage is good, I suspect this might be your issue seeing as your gauge never reads 100% full, and doesn’t hit empty.

Third, all this grounding advice looks good, and everyone’s looks cleaner than mine lol. However, the manual does call for you to run a dedicated ground. Here is a screenshot. If nothing else works, you might try that. Maybe temporarily hose clamp wire to the old fuel connections on the sending unit, and run it under the car and through the firewall (or maybe just up through the engine bay and through your window) and connect to the RTX control box. Again, this would be temporary, just to see if it makes a difference. If it does, run a new ground wire through the grommet in the trunk, and terminate to the sending unit. I pulled my back seat and inner panel out to route the new ground along the existing wire path up the drivers side of the car, then terminated to the control box.

RTX manual is here: https://www.dakotadigital.com/pdf/RTX_manual_main.pdf

I also posted a screenshot of the manual adjustment procedure… and a picture of my sending unit. I’m struggling with a leaky gasket right now and am probably going to replace my tank, so don’t judge my somewhat temporary ground connection . I hose clamped a male spade connector to the fuel line so I could disconnect the ground while I tried to figure out my leak. Green new ground has a female connector. Ugly, but it works.

Good luck, and let us know what you find!