Fuel Gauge - Calibration Issues

[MB750]

I got the dash temporarily installed today, just to see the gauges spin and whatnot. Everything came up normal, except for the fuel. I remember reading a few threads on here about having to calibrate it. So I plugged in the little push button and followed the procedure. Got the needle to the 7/8 tank level, held the button for 2 seconds, then the needle goes back to E, but the needle never went up to wherever 58 ohms should be. I put 5 gal in the tank so somewhere between 1/4 and 1/2 tank I would assume.

I about pulled my hair out trying to figure out why it wasn't reading. I even stuck a random resistor I had in my electronics box in the connector terminals just to see the gauge say something other than E.

Then it hit me....

[Mike.Bray]

Air gap problem.

[MB750]

Yup, WAYYY too much resistance there.

FYI, you can remove the wire and pin from the plastic connector, but you sacrifice the little "wings" on the pin that hold it in place. There's no way to insert a tool to remove the pin on these really little connectors. I moved it where it needs to be, but now I can physically pull the wire and the pin comes out. Regardless, it stays in place when connected so I'll run it.

[Windsor]

That's a Molex connector, yes?

The Molex kits are pretty cheap (I get mine from DigiKey), the "cost" is really the time to cut'n'crimp to redo.

Might be worth it for the peace of mind, but up to you.

[i.e.427]

De-pinning the connector is pretty easy. And you lucked out................. it's much harder to find at the fuel tank side of the wiring....... after the body is on the car.

Ask me how I know?

[MB750]

Thanks for the tips fellas. I tried every way I could to get those pins out but couldn't figure it out so in the end just yanked it. Typically I can see somewhere to shove a pin or small screwdriver to release a catch, but even with a magnifying glass I couldn't see anything.

These connectors are very small, smaller than my index finger. If they are Molex they don't show it, and I couldn't find a picture of this exact connector on the net:



I removed the sacrificial connector so you can see what I bent to get it out. Those little "wings" are now pointing forward. Before the connector was installed they were pointing backward. That's what locks it in the connector itself:



So, I bent them back. Now the terminal end holds itself in the connector.



Recently I bought a miscellaneous kit of Molex connectors and terminal ends, but they're 4X the size of these and white. I'm trying to maintain uniformity with the other gauge connectors. I'll probably send an email back to FFR with the first picture from this thread, just asking them where I can source these exact connector kits.

[michael everson]

Either put a new connector on or just solder the wires. BTW you dont even need the ground. Its grounded through the other ground wire powering the gauge.
Mike

[MB750]

Either put a new connector on or just solder the wires. BTW you dont even need the ground. Its grounded through the other ground wire powering the gauge.
Mike

I could do that, but I'm trying to maintain uniformity.

FYI, I'll admit I was just lazy. Searching this morning after coffee (and noticing the numbers on the female side of the connector in my picture) gave better results:

Molex Micro-Fit 3.0 series connectors. Male end connectors are 43645-XXXX, female ends are 43640-XXXX. The end configuration "XXXX" dictates number of pins.

[MB750]

Digikey to the rescue! (Mouser website offline for some reason)

https://www.digikey.com/en/products/...4AOFgQFhBtOlKA

Molex makes a few different sizes of terminal ends for these Micro-Fit 3.0 connectors. One size fits 20-24 AWG wires, another fits 26-30 AWG, and another is just 18 AWG. My application will need the 18 AWG terminal ends. Since they're cheap I'll probably get a hundred of each, and an assortment of connector pairs just for inventory.

[i.e.427]

Inexpensive de-pin kits are available from ebay and Amazon.

Frank

[MB750]

Inexpensive de-pin kits are available from ebay and Amazon.

Frank

Wow, yea, much cheaper than from Molex. I almost spent $26 for a single tool from them. Granted, it showed exactly how to remove the terminals from these exact connectors, but some of those kits on Amazon come with 30 different types of removal tools for $10.

Also, the Molex instructions specifically say that these terminals are sacrificial. They way they're removed destroys them. I don't know about that... The tool goes into one side, presses down the little tang, then with light pulling pressure you insert the tool into the other side until the tang is pressed far enough to pull the terminal out.

Maybe they just wanna sell more terminals. If I ripped mine out and reused it (questionably...), surely using the special tool will allow reuse.

[Windsor]

Inexpensive de-pin kits are available from ebay and Amazon.

I bought a 109pc kit from Amazon much like the one you flashed in one of your videos. After closer review of the tools, it was actually a 49pc kit with a truckload of spares. I left a review that explained it out better.

Still not a bad buy for $20.