Sending unit recommendations

[bugger-off]

I guess if it operates correctly I won't care where it's made.

[bnam]

[bugger-off]

Yes, and I was told that the ohms testing should be performed on a stand at the same stance that would recreate the position of the sender base on the tank. BUT, I don't know if that's true or if it makes a difference. My guess would be it doesn't matter.

[baldessariclan]

[bugger-off]

Well, my “good” VDO unit came and, yes, it was made in India. It tested good with 73.4 ohms and 4.3 ohms. Big problem: If you go back to my “report” on the previous page, this new VDO is doing the same thing on a dry run.

Gauge and/or vibrator?? Or do I just go back to filling up every 200 miles?

[talljordan]

I reread your report. My money is on the gauge itself.

Have you checked that you are getting the correct voltage out of the vibrator? I believe thats 5v
_________________
1972 Super Beetle, Parked until adequate restoration funding is acquired in restoration!

Wanted: Male computer diagnostic plug end

[bugger-off]

That’s my next move. I have tomorrow off with decent weather.

My wive LOVES being a bug widow.

[viiking]

[viiking]

[bugger-off]

[viiking]

The only other thing I can think of before you do too much else is to actually measure the resistance being received at the meter.

It appears you have done a great job measuring with a combination of rulers in the tank and the resultant resistance. Not knowing how you did this but I assume you never reinstalled the meter along with the grounds every time you changed the level in the tank? It would be ideal if you could reproduce the "real life" situation.

It would just be simple to at least measure the resistance at the fuel sender with the wiring disconnected and compare that to the end of line resistance being received at the meter when it is connected. At least that way you can discount any resistance issues with the wiring.
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3

[heimlich]

[baldessariclan]

Would suggest/request you take and post some pictures similar to those I did earlier — i.e. show us where your sender’s arm is sitting when the gauge is reading at the full line (1/1), 1/2 line, 1/4 line, & R-line. Plus maybe also what your gauge is showing when the sender arm is up against the upper and lower stops as well.

I can do likewise w/ my spare sender and the fuel gauge in my car — might help give you a better feel for if maybe it’s actually the gauge that’s out of tolerance and/or going bad, rather than the sender.
_________________
1971 Standard Beetle — fairly stock / driver

baldessariclan -- often in error, never in doubt...

[bugger-off]

Yes, I can run the testing again with pics and get them posted.

[baldessariclan]

Ok, here are the readings I’m getting with that spare NOS VDO sender I’ve got. I obtained it a few years ago from a Samba classifieds seller, IIRC — it’s probably 1990’s or later production, I’m guessing (?).

Here’s the sender arm position and resistance reading when the fuel gauge is reading “1/1”:

Sender arm position and resistance reading when the gauge shows “1/2”:

Sender arm position and resistance reading when gauge shows “1/4”:

Sender arm position and resistance reading when gauge needle is on the “R” line:

_________________
1971 Standard Beetle — fairly stock / driver

baldessariclan -- often in error, never in doubt...

[baldessariclan]

I decided to also dig out and test the old original sender that was on my car when I bought it. The male electrical connector tab had been bent up and partially cracked by a PO. I babied it along for a couple years, but it eventually broke off completely — ugh.

So I did a rough fix by drilling a shallow hole next to the tab base and gluing a wire in there, and that worked for a few more years — until it started cutting out sporadically, and I decided to source and obtain a new sender.

Anyway, I cleaned that old sender up, re-glued the wire in hole, and here are the readings I got with it:

Here is the sender arm position and resistance reading when the fuel gauge is showing “1/1”:

Sender arm position and resistance reading when gauge shows “1/2”:

Sender arm position and resistance when gauge shows “1/4”:

Sender arm position and resistance when gauge needle is on the “R” line:

Here’s the resistance reading and gauge needle position when the sender arm is resting on the lower stop (tank “empty” -?):

Note that it’s been my experience that the fuel gauge in my car seems to read reasonably accurately — i.e. when the needle is on “1/2”, it usually takes 5-6 gallons to fill the tank; needle on “1/4” takes about 8 gallons to refill; and needle in “R” zone usually requires 9 to 9-1/2 gallons to refill.

I’ve never run it down to completely empty, but on one occasion got the needle down near the far left “point” of the “R” (reserve) zone triangle, and it took about 10 gallons to refill on that occasion…
_________________
1971 Standard Beetle — fairly stock / driver

baldessariclan -- often in error, never in doubt...

[bugger-off]

Wow, man! Thanks for all the hard work testing and posting pics. I have yet to run my tests but your’s look incredibly close to my previous results.

What really throws me off is the 1/4 tank reading when the float is down just a couple inches! Is that normal? Am I being unrealistic that the gauge would ever read 3/4 full for any period of time?

Another thing is that my arm bottoms out when the tank is a quarter full. Because of the tabs, or “stops”, on the base the arm/float don’t come close to moving any further down with the actual fuel level in the tank.

[viiking]

To baldessariclan.

That has to be one of the best and most complete descriptions of how something works. Clear, concise, fact based and scientific.

I think those photos and the description warrant a "how it works" sticky for others to understand how it works. It absolutely shows the non-linear level change with float angle change and how it corresponds to my photo of the change in winding turns inside the wiring.

Well done!
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3

[MrGoodtunes]

[bugger-off]

Inclement weather today with no garage space available. Hopefully tomorrow.