Re: [DeTomaso] Tank gauge

[Thomas Tornblom <Thomas.Tornblom@Hax.SE>]

> From: MikeLDrew@aol.com
> Date: Fri, 11 Apr 2003 05:49:15 EDT
> Subject: Re: [DeTomaso] Tank gauge
> To: Thomas.Tornblom@Hax.SE, detomaso@realbig.com, detomaso@detomaso.nu
> 
> 
> In a message dated 4/10/03 16:04:36, Thomas.Tornblom@Hax.SE writes:
> 
> << I added 5 liters at a time, noticing the gauge reading and resistance. >>
> 
> >>>Just one question?
> 
> What the hell is a liter? :>)
> 
> Mike (GALLONS baby, GALLONS!)

You mean that standardized unit that is different on each side of the atlantic 
ocean? ;-)

Oh well, for you Mike, and anyone else who can't convert, I have created an 
alternate version :-)

Just don't ask me to convert from decimals to fractions...
---
In my quest to get properly working instruments, I have spent a few hours 
measuring the tank sender resistance and noticing the gauge reading for various 
amounts of fuel.

As I still have the car on jackstands, it was quite easy to drain the tank so 
that I knew the exact amount of fuel for each measurement.

I added 1.321 gal at a time, noticing the gauge reading and resistance.

Here's what I found:

gal us	gal imp	R (ohm)	gauge
---------------------
empty	empty	~2k 	empty--
 1.321	 1.100	321	empty-
 2.642	 2.200	272	empty+		lamp goes out
 3.963	 3.300	234	1/16
 5.284	 4.399	208	1/8+
 6.605	 5.499	180	1/4-
 7.926	 6.599	160	1/4+
 9.247	 7.699	135	3/8
10.568	 8.799	115	1/2-
11.889	 9.899	100	1/2+
13.210	10.999	 88	9/16-
14.531	12.099	 75	3/4-
15.852	13.198	 60	3/4
17.173	14.298	 48	3/4+
18.494	15.398	 27	4/4-
19.815	16.498	  3	4/4+
21.136	17.598    2.5	4/4+

When I filled the last few 0.1321 (0.110) gallons up to 21.136 (17.598) gallons, 
the fuel level climbed up 
into the filler tube, but sank slowly as if something was leaking. I believe the 
excess fuel drained into the carbon canister. I have a late aluminum tank by the 
way.

All gauge readings were taken with the ignition on, a battery charger active, no 
lights on.

For those (like me) contemplating replacing the instruments with better working 
VDO:s, VDO North America has a fuel gauge in all common series that probably 
would work fine. They have a gauge with 240 ohm (empty) - 33 ohm (full), and 
adding a ~30 ohm resistor in series with the sender would probably work 
reasonably well.

This type of gauge is not available from VDO Germany. The German gauges are 
either 3 ohms empty and 180 ohms full (opposite from veglia) or 60-90 
(adjustable) empty and 0.5 ohms full.

I will get one of the 240-33 gauges from Summit and try it out with the stock 
sender.

Cheers,
Thomas (can convert to gallons, both types)