Fuel gauge stays at half-full

[Roberto]

replying to madmmac, I was filling it with 12 gallons (as I recall) or so when
it got close to empty. Not driving it much right now but will be soon. Will record how many gallons to fill it.

Also, thanks to Jdowty3. I wil try cleaning the plug contact at the sending unit...thanks for all the tips.

Rob

[madmmac]

12 gallons is just under a half tank.

Tank is about 22 gallons

[Bill in OKC]

My fix might only be a possibility if the gauge reads half full when the tank is full (and the sending unit is good). IIRC there are a couple of tabs surrounded by insulating pads on the back of the "pod" (there is one pod for the fuel and one for the oil) that unscrew from the back. There are two of these tabs and they have wires soldered to them . One of them rests very close to the metal case when the gauge is assembled. On my car it actually contacted... I'll see if I can get a picture tonight.

[jclotter]

My fuel gauge also got stuck somewhere in the middle.Turned out that the needle was bent and got stuck on the rim of the gauge face!

[PatrickB]

Wish mine would stay at "Half-Full!"

As soon as the needle moves to FULL, it moves far too quickly to Empty!!!

[Roberto]

Thank you all for the tips and advise. I think the problem is fixed.
Last night I did clean the plug contacts real well with lacker thinner
and using a q-tip with partially remover cotton, was able to clean out the inside of plug holes. Also, removed the sending unit and took it apart to make sure the float was free and every thing looked right inside the tube. Oh, and I did disconnect the bat first.
Put everything back together and went to fill it up and viola...the needle jumper to full and it took 17 gallons. While the sending unit was out I shined a light in the tank and saw that there was about a quarter of a tank and the guage was reading a quarter of a tank (or normal). I did notice that the gas filler tube on the car gets airbound and gas comes up to shut off the gas pump. This happened several times at the gas pump.I am certain this was not happening before because I saw gas at top of filler tube on gas tank and tried 2 time to put more gas in and could not. And the tank read half full. So whatever I did, seemed to work...not quite sure what worked but suspect the contacts on the plug may have been dirty??

Thanks again everyone.
Rob

[Bill in OKC]

I'm glad you got your gauge fixed. If anyone else might need these, here are two pics that I took last night:

The arrow points to the tab I had to bend and the circle is where it was making contact.

[Dan in Pasadena]

Bill, So you're saying that metal - when it was clinched over as it originally was, was causing a connection between it and the solder on that round red "pad" for lack of a better word? I guess I am wondering how it ever left the factory in that condition? Wouldn't it have shown a malfunctioning gauge then? How could it have changed over the years.

Roberto, This "plug" and the "holes" yore talking about...you're referring to the electrical that plugs into the sender? All you did was clean the plug's tab/s and slot/s with lacquer thinner, is that what you're saying?

Last, is it typical that when I pull my sender there will be some sediment or rust/junk in the bottom of the tank? If so, what should I do about it? Pull the tank to somehow wash it out? If its not rust and the tank shows no internal corrosion is there any reason to use that POR 15 gas tank refurbisher stuff that you slosh around in there? Or should I just let the filters catch the stuff (assuming it is a small amount)?

[falcon]

Sorry for the delay in getting results back. I finally had some time to drive about 40 miles this weekend, however I did NOT notice any movement of the gauge indicator. I have about 240 miles on the trip meter and that usually would move the indicator below the 1/2 full mark. Maybe the indicator is stuck as per the previous posts. I'll try to check it out this coming weekend.

5/11/06 Drove another 50 miles or so. Trip meter shows 290 miles. Indicator on guage reads below the half mark. I'd say the problem is fixed by putting in a new sender at a cost of about $100.

[Bill in OKC]

Dan, yes it probably did work at one time - I guess the connector could have turned in the case over time and rotated the 'prong' into contact? I don't really know and that is what made it so tricky to find. The metal 'prong' that I bent is physically and electrically the same piece that is soldered and also the blade connector on the backside. The factory went to a lot of trouble to insulate it from the case, but it was making contact when the two pieces were assembled.

[Roberto]

Dan,
Yes ..all I did was clean the elictrical plug, both on the sender unit and on the cap (plug) that connects to it to fix mine. I did use lacquer thinner because thays what I had handy, but am sure another cleaner would wort as well. good luck..

Roberto in CT. 87 911 Carrera

[Joe Bob]

Not to hijack the thread....
http://forums.pelicanparts.com/showthread.php?threadid=281302

Similar but diff problem....

[Jascha]

Fuel Tank Level Sender Repair...?

I was troubleshooting my fuel level gauge that went “silent” and discovered that the problem (open circuit) is with the fuel tank sender unit. If one is careful these can be taken apart to inspect the float and sliding wire guide mechanism.

In my case the wire (acts as a rheostat) apparently snapped (must be the “heavy gas” in PA).

Have any of you replaced the naked wire and can tell me the type you used and any trick to keep it taut while still being able to solder the end-points… (?)

Thanks!

[jdowty3]

I was going to suggest just replacing it but, WOW - when did the tank sending unit become $108. I think trying to repair the wire would create a higher resistance and throw the guage off but I'm not an EE. Maybe look for a used one. I have a spare but I think I'll hold on to it for now.

[labdag]

I had the similar issue: gas gauge stuck at 1/2 full. The fix was to remove tank solenoid, remove float mechanism from tube and CLEAN (with sandpaper) central shaft which float moves up/down, spray some wD40, and put back together. Just be careful not to brake any of the wires. Also, you should measure the Resistance (K ohms) at:
Empty-67K ohms
1/2 Tank - 35K ohms
Full Tank - 5K ohms

pics shows Resistance at Empty, Half, Empty





Gas gauge now works. shows 3/4 full

[Dodge Man]

My new sender was sticking and my wires were proper. The float on my NEW sender was sticking at 3/4 when I filled the tank and 1/2 when I drove. Since it is a plastic float on a metal wire, I pulled the sender and gently rotated the sender to make the float move. After about 15 minutes the float moved easily at low inversion angles. Solder/flux on the wires or a burr inside the plastic float? Sometimes you have to get a touch of wear to get things to settle into place. I followed KISS(Keep It Simple Stupid guidelines) and attacked the simple procedures first. IMHO Why tear apart the motor when you only need a new spark plug & valve adjust? Was your old sender just worn out? Dash gages are not precision instruments due to cost constraints. I did not want to start chasing electrical issues when my old sender died from non-movement when the car was held prisoner at the Porsche Stalag (PS Racing in Burbank). Best of luck.

[FL911SC]

I recently learned this trick for some quick troubleshooting as well.
With the battery connected, and the key in the run position, remove the plug which is connected to the top of the sender. It is best to remove the three nuts holding the top plate and the place, before turning the key on. When you removed the plug, the sender should drop to empty 0/4. You can then use a piece of wire to short the middle connector in the plug (not on the sender) to ground, which will cause the gauge to go to full 4/4. If you short the top connector on the plug, the fuel level warning light will come on.

I found this to be a quick way to determine if it was the sender or the wiring/gauge which was causing the problem and I didn't have to remove the sender.
The new sender is on order!

[garment]

This is a great tip, and I was able to duplicate it (used a piece of wire to short the plug to make the gauge go to 4/4 and make the fuel warning light go on). However...

I've got a brand new sender in the tank, and I still have the stuck gauge. And, this is a replacement gauge as well. What could it be? When you got your new sender, did that fix the problem?

Originally Posted by FL911SC

I recently learned this trick for some quick troubleshooting as well.
With the battery connected, and the key in the run position, remove the plug which is connected to the top of the sender. It is best to remove the three nuts holding the top plate and the place, before turning the key on. When you removed the plug, the sender should drop to empty 0/4. You can then use a piece of wire to short the middle connector in the plug (not on the sender) to ground, which will cause the gauge to go to full 4/4. If you short the top connector on the plug, the fuel level warning light will come on.

I found this to be a quick way to determine if it was the sender or the wiring/gauge which was causing the problem and I didn't have to remove the sender.
The new sender is on order!

[whiterabbit]

Garment I have a similar problem on my car. I have replaced both sender (new from this site) and also had the guage rebuilt. Still the guage sticks when it gets down to half full. My car is a ROW 3.2. Is it possible that the ROW cars have a different sender depth unit or an ROW tank is different? When I run the test to short out the wires the dash guage works correctly so its clearly something going on in the tank.

[garment]

My issue seems to be resolved. Replacing the sender didn't do it, but swapping the gauge did. Not sure what the issue was, but definitely glad to have it resolved. Good luck with yours!

Originally Posted by whiterabbit

Garment I have a similar problem on my car. I have replaced both sender (new from this site) and also had the guage rebuilt. Still the guage sticks when it gets down to half full. My car is a ROW 3.2. Is it possible that the ROW cars have a different sender depth unit or an ROW tank is different? When I run the test to short out the wires the dash guage works correctly so its clearly something going on in the tank.