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Discussion Starter · #1 ·
I have a VDO fuel gauge that is supposed to be matched to the Ford sending unit. However, it reads empty when the ignition is off and past full when the ignition is on. The tank has about two gallons in it. I am running a carb setup and the wiring seems fairly basic. power, to the gauge. wire from the post labeled 'sender' to the sender and then from the sender to a ground.

The fuel gauge reads:

Empty with the ignition on and the connector removed from the sender

Past Full with the connector jumped.

How do I test the sender?

I have a basic voltmeter, but I'm not sure where to turn it to on the dial.
 

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Blue Oval Scribe
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The gauge itself usually needs a ground as well...

Please provide the fuel gauge part number, a photo of the back of the gauge (if possible) so we can help further...

Also, to test the fuel sender you use the ohm scale, not volts. You will need to remove the fuel level sender from the tank and bench test it by connecting your ohm meter and then moving the float arm manualy and reading the meter scale.

HTH...
Mark
 

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Discussion Starter · #3 ·
The Summit Racing Part number is VDO-301302

VDO Series 1
Sending Unit: Electrical
Sender Ohm Range: 240 ohms empty, 33 ohms full ohms

ewww, it's not going to be easy to remove that thing with the trunk aluminum riveted in! I'll pull it out tonight and let you know.
 

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As Mark says try the grounds Ist, Ground the Guage also

jimmy O
 

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Donor Tank that had been sitting?? This problem drove me nuts with my smith's gauge and ford sender. I kicked the tank and it worked great. I had to do this for a few fillups for it to work consistently. The float was just sticky .... possibly your problem???
 

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Matt,
One of the wires on the sender is a ground and is not only grounded through the wiring but also through the body of the sender and then through the tank to the frame. If you have the wiring reversed at the sender then I believe it will do as you are seeing since it sees ground when the power is on. You may want to try swapping the wires at the sender connector to see if that fixes it.

Cheers, Rod
 

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I believe the Ford sending unit for 1987 and later is 16 ohms empty and 158 full. I think you have the wrong gauge.
 

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Discussion Starter · #8 ·
I bench tested the sender and it started at 20 ohms (empty) and went up to 15X and then the gauge would go blank. At least I think that's what it did. The numbers jump all over the place.

I think I have the wrong gauge, I'm on hold with Summit now...

[ March 21, 2007, 07:37 PM: Message edited by: Matt L ]
 

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I'm confused. Are you using the stock sender with a gauge designed to function in the 240 empty to 33 full range? If you are using a stock sender, you will need a gauge that is designed to work from 16 to 158. Your symptoms lead me to believe that you have the wrong gauge.
 

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Discussion Starter · #10 ·
I talked with Summit and they said that I have the right gauge and 240 ohms empty, 33 ohms full ohms is correct, but he gave me their tech dept number, so I am on hold with them now...

Yes, I am using the stock sender and a VDO gauge that is supposed to work with the factory sender.
 

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Discussion Starter · #11 ·
According to this site It should function in the 240 empty to 33 full range.

however, according to this site it should work from 16 to 158...
 

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Discussion Starter · #12 ·
So Summit says they don't sell a gauge that works in the 16-158 range and they don't sell a sender for the Mustang. Then he looked in a "supplement" catalog and found the ultralight in that range, but no classic style gauge. Ugh!

He looks further and then finds an Autometer Classic that works in my range. This one. So the guy tells me the only one that will work in that range is an Autometer... I continue to research it a little further and find this one that is the same as what I have, but in the 10-180 range. Will it work?
 

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Blue Oval Scribe
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Woah, woah, woah Matt...

Let's get a few things straight here so we can help...

Just answer these questions yes or no (and ignore the sites you linked to, the first is wrong and the second is referring to Stewart Warner and Auto Meter senders for 240/33)...

Are you using the STOCK Mustang fuel level sender from '87 and up?

You are using VDO Series 1 301-302 Fuel Gauge?

Is the gauge properly wired with a power, ground, and sender wire (3)?

Is the sender properly wired with the S wire from the gauge to one terminal and the other terminal to a solid ground?

Answer these and we can go forward, but it looks to me like you either need to swap to the 301-301 gauge (closest in ohm rating) or replace the fuel sender with a custom one that reads 240/33...

EDIT: Corrected PN...

HTH...
Mark
 

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Matt,
What year stock sender is that gauge supposed to work with? Maybe that's the confusion.

A stock '90ish sender makes the gauge read full at 145 ohms and empty at 22.5 ohms.

How many ohms are you getting out of the sender right now? (you can hook up your multimeter at the gauge) After getting a reading, you can add enough fuel to bring it up to a half tank. That should give us a clue. You can then fill it and let us know.

The sender is in the ground circuit of the gauge.


d



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Discussion Starter · #15 ·
Are you using the STOCK Mustang fuel level sender from '87 and up?
Yes

You are using VDO Series 1 301-302 Fuel Gauge?
Yes

Is the gauge properly wired with a power, ground, and sender wire (3)?
Yes

Is the sender properly wired with the S wire from the gauge to one terminal and the other terminal to a solid ground?
Yes
 

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Discussion Starter · #16 ·
How many ohms are you getting out of the sender right now?
I bench tested the sender and it started at 20 ohms (empty) and went up to 15X and then the gauge would go blank. At least I think that's what it did. The numbers jump all over the place.

 

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Matt,
It sounds like you have proved your sender is 16 - 158 ohm with your test. You have the wrong gauge. I looked at the VDO web site and it seems they don't make one. I have had autometer and now have classic instruments. Both came 16 ohms empty - 158 ohm full (for use with 1987 and newer mustang stock sender). Pre 87 uses 240 ohms empty - 33 ohms full. The gauge you got. Here is the gauge I am using now. http://www.classicinstruments.com/gaugeselector.aspx?ProductCode=HR01SLF&SeriesCode=HR
 

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I just ran into this problem with the Autometer Phantom IIs a few weeks ago. They do not make a fuel gauge for 16-158ohms.

Breeze sells the older stock float sender you need (pre 87) brand new that will give you 240-33.
http://www.breezeautomotive.com/details.php?prod_id=222
MAKE SURE YOU VERIFY WITH THEM THAT THIS IS THE PRE 87 SENDER.
It is a 100% plug and play replacement for the 87-93 sender. $92. Sometimes spending a few dollars will save you a big headache. This is one of those times. It takes only a couple of minutes to put in... once you drop the tank. A custom sender will be a far larger headache to set up and not much less money.
 

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Blue Oval Scribe
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Damn! I forgot the earlier senders had the other rating...

Good catch David!! :D

I would do that Matt, since you have the gauge and I assume it matches your other gauges. Simply put the other Mustang sender in to match and you'll be good to go...

I don't think the Breeze one is the '83-'86 model (which is what you need)...

HTH...
Mark
 

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Discussion Starter · #20 ·
I just called Advance Auto and they sell it for $112.88. mo' money, mo' money, mo' money!

This is why I call this car my 'black hole', all of my money gravitates towards it...
 
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