Del70

Installed new tank and sending unit. I put fuel in it, had ¼ tank of gas, ran the car up put to the station, put in $25 worth, which was 9.6 gallons and gauge went to full, which it should not have...based on the gallons..tank spec says it is a 20 gallon. I used the old unit and checked the gauge.. it is working fine. New gauge is reading 87 ohms, spec list 0-95 ohms. I did check the new sending unit before installing it ...hooked to the gauge and it read correctly. However If the arm angle is off then it would read incorrectly..., so either way I think I have a bad sending unit
... Has anyone ran into an issue like this?
thanks

don71

You may not have any thing wrong at all. Drive it and monitor your consumption over at least one more full tank. I don't think you have any thing to worry about right now.

What I'm saying is a quarter tank on the guage may not equate to five gallons. It probably has more gas in it, more like 8 gallons.

Next time, fill it up all the way. See just how far full really is on your guage. Its likely to go a little past F.

Del70

agree, the next simple test is to see how many gallons will fill it.. may just wait until I run it down to 1/2 tank to get a good base line thanks

oldcutlass

The issue is that most of the gauges were not very accurate and it depends on the contours of the tanks. Some models would ride on full forever and then slowly drop to 1/2, and swiftly go to E. The gauges would swing between 1/4 and 3/4s. Once you get the hang of how your gauge works, then you adjust your fueling habits.

Destructor

It's just a float, half may only mean half way from the top of the tank to the bottom of the tank but may not represent actual volume. A home heating oil tank is similar.

don71

Very well put. Ohms doesn't exactly mean volume.

Koda

The only thing you really need to know is precisely what that gauge says when it means Empty. My 72, that line means You Are Done. My daily driver, you got 25 miles on the E line left.

Tedd Thompson

Mine flat quits at 1/8 mark on the gauge. Found this out in Montana and had it towed to a shop thinking the fuel pump had died. I would run it down till I was very uncomfortable( with a backup can in the trunk) and make a mental note how far you can go, depend on that....Tedd

67442nut

I installed a new, repro, tank sending unit, some time ago.
I've learned that when the gauge reaches empty,
I still have approx. 5 gallons, or 1/4 tank in a 20 gallon tank.
When I fill up, the gauge only goes to 3/4.
Apparently the calibration is off by a 1/4 tank on the new tank unit.
A little irritating, but, at least I know my fuel status now.
I'll live with it 'til the next time I jack the rear of the car up.
Looks like the reproes are having a problem with calibration.

Macadoo

This is exactly what mine does. I assumed I had a bad sending unit. It rides on hot-light for a long time, quickly drops to half, then more quickly to E. Would a new unit improve on this?

oldcutlass

No Mac, unfortunately that's the way most of the gauges work.

Fun71

Wow, both my '70 and '71 seemed very linear from F to E, so much so that I could use the gauge increments to judge how many more miles I could drive before needing fuel.

Macadoo

I stand corrected. This morning I pumped the tank out until it read 1/8th. So I thought I'd drive around our [country] block a couple of times to run it out. I made it about 150 feet. Mine runs out at 1/8th tank. That won't do.

oldcutlass

So now you know...

Fun71

Yeah, it is good to know when you really, really need to find a gas station!

It also sounds as if your pickup could use some calibration. Both of my cars had about 2 gallons left when the needle hit E. I confirmed that more times than I care to say.

oldcutlass

I've never run mine out of gas. My needle as most in that era will have wide swings as it drops down from 1/2 to E when making turns or braking. My theory of these older cars when the needle stops moving your out of gas. With that said, I usually fill up when the needle drops below 1/2.

Macadoo

Could be I snagged it when I was pumping out the tank. Is there any way to know what the orientation is supposed to be? I could see this being a very long, painful process. Bend, reinstall, install tank, add gas, pump out the gas, remove tank, repeat. Maybe I'll compare to Allan's pics in his Another MAW Disaster thread.

442craig

Had the same thing happen too on my 68. Replaced the tank and sending unit. It would read a little over half a tank when it was full. I dropped the tank and bent the float. It now reads just over 3/4 when full. Haven't had the heart to pull it again. Sure would be nice to have an access panel in the car to adjust this!

Craig

Macadoo

I got my tank off and sending unit out. And guess what....it works! Ugh. Must have been a bad connection. With the unit sitting in the trunk, I hooked it up, grounded it, and played with the float. All the way up reads a bit over "F". All the way down nails the "E" right on. Problem is the filter sock is torn and the main cap and ring are VERY corroded. I went ahead and ordered a new one from Inline Tube's eBay store. I hope it's as accurate.

mrolds69

Uhhh...the fact that it works fine out of the car means nothing. I tested my repro before I put it in. It worked perfect. I didn't check the arm against my original arm. It doesn't read full like it should but close enough.

Macadoo

Lol, yeah, no, I mean i realize it depends on how it hangs in the tank. I was just excited to see the needle actually move off of the hot light. I'm keeping the old one to compare with the new before I install it.

Macadoo

Sorry Del70. I kind of hijacked your thread.