Fuel Gauge tomfoolery

[Curious Hound]

Woooaaahhhhh, can anyone tell me why the sending units are like $130!? Yikes. I was gonna order one but after seeing that, I think I'll just smack mine with a hammer.

I agree that sounds like a lot. But, it does reside in a harsh and dangerous environment and the manufacturer probably shares some liability if it causes a catastrophic failure. Intrinsically safe devices are expensive.

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[chewy012]

I agree that sounds like a lot. But, it does reside in a harsh and dangerous environment and the manufacturer probably shares some liability if it causes a catastrophic failure. Intrinsically safe devices are expensive.

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Well when you put it like that....... Hahaha

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[kimcrwbr1]

Short the hot wire going to the tanks to ground and the guage should read full with the key on. Chances are very slim both senders failed at the same time. Did you smack the dash board to see if you get a reaction with the key on?

 

[chewy012]

Short the hot wire going to the tanks to ground and the guage should read full with the key on. Chances are very slim both senders failed at the same time. Did you smack the dash board to see if you get a reaction with the key on?

Yeah I smacked the dash, and molested the switch a bit, nothing. But hitting bumps, knockin' curbs, gunnin' it and hard stops make it move. And after about 10 minutes of driving in the afternoon it'll work it's way back up. I'm thinking it's just shot. I'm a pull it one of these weekends and clean it and see if I can do something to tighten the connection up. I threw Lucas and seafoam (not together) through the tank to maybe clean it, no avail. The gauge works properly when I switch to the rear tank. On the front tank (the problematic one), the gauge goes back from E (key on) up to 1/4 when the key is off, even when full. I'm sure it's just frigged

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[RonD]

As said, since the gauge and wiring work fine on one tank then it comes down to wire or sender in the non-working tank.

You can repair senders, in most cases, good read here on Ford fuel gauge system: https://www.fordification.com/tech/fuel-sending-units.htm

And what to expect when you pull out the sender

You can get universal senders that can be adapted for your system, 10 ohms empty 180 ohms full is a common type, $35-$60

The higher, 180ohms, won't hurt anything, gauge needle just won't come off of FULL until a few gallons are used, the more important setting to be correct is EMPTY, 16 ohms which a 10 ohm sender would show when about 1 gallon was left.
10 ohms to 180 ohms is a difference of 170 ohms
Assuming 20 gallon gas tank its 170 / 20 = 8.5 ohms per gallon
It isn't quite that linear with senders and floats, but close enough for this

So when needle is on EMPTY, 16ohms, there would still be a little gas left in the tank, a "reserve", lol.

 

[chewy012]

RonD, always comin' through haha. Thanks again for all the good information, I appreciate the help!

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[chewy012]

Welp, this is now the least of my worries. slave cylinder just went out :/


... damnit

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[chewy012]

For antone still keeping score, it was in fact a pin hole in the float.

Cut the access hatch, did kind of a hack job but it sits under the toolbox.

Pulled the pump and float, was able to get all the fuel outta the float and then I put a drop of solder over the hole. Tested it in a beer can filled with gas, seems to be tight. Working gauge again, woohoo!

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[RonD]

Good work

Wouldn't have guessed float with those symptoms

 

[chewy012]

Good work

Wouldn't have guessed float with those symptoms

Yeah me neither, especially as it would intermittently come back...

Either way, as soon as I felt it sloshing I saw the pin hole and was like yup. That's it!

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[chewy012]

At least if it leaks again, I r won't take long to fix

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