Put 10 gallon in the tank but my fuel guage still shows E for empty ....WHY?

[MrY]

My tank meter not working ! Just filled 10 gallon and it shows nothing.

Where do I start looking ? What ohm should the wire behind the gauge read ?

Any one know.

Any one had this problem before ?

When ignition turn off - then the gas pointer diapers

When ignition turn ON - the the gas pointer goes to E (empty)

When I go in the trunk and disconnect the brown wire that comes from the tank sender - then the gas pointer goes quickly to F (full).

I have found the ground wire and ran a long wire direct to negative on battery but still stuck on E

and I cleaned the ground surface the wire/bolt from tank negative taps into the frame but still stuck on E

 

I hate not knowing how much gas I have before the car empty and die on me..... 

[Bloo]

Make model and year always helps....

 

I see from the dash picture it is a Buick, and the gas gauge worked the same for decades on those. The sending unit, when disconnected, measures 0 ohms (or as close as is possible) empty and 30 ohms full.

 

Since you disconnect the wire at the tank and the gauge goes full, that indicates normal operation of the gauge and wiring. The trouble has to be inside the tank. Probably your sending unit's float is sunk. Or, the sender could be electrically shorted somehow. My guess is it is the float. Time to pull the sender out. Good luck, and let us know how it works out. :)

 

 

[MrY]

Yes it is a Buick 1955 Special, and I am under the impression as previous comment that the fuel gauge is working fine

and the problem is with the sender in the tank.

I see previous owner has made a new wire for the ground from the sender to the frame but that did not fix it

So as previous comment point out it is probably inside the tank and I need to drop the tank and check if the float is detached.

If the float is gone the arm would be down all the time as of it was empty, just as the gauge is showing.

So now I need to drive the car until it is dry of gas in the tank (bring a spare gas reserve) and then dropping it would be easier ....

 

[FLYER15015]

Bloo is right.

Based on your tests, we now know the dash gauge works.

Time to pull the sending unit.............

Sorry about that. i know it's a "pain', but think of it as an adventure, and take your time.

 

Many of us have been down this road, and it gives us something to talk about,

when we get to the "home".

 

Mike in Colorado

 

PS; There should be a drain plug on your tank for the last few ounces, and of course you know how to siphon a tank.

       Or were you one of the good little boys ?

Edited September 9, 2020 by FLYER15015 (see edit history)

[JACK M]

Sounds like you could pull the sender from the trunk, is so then no need to drain.

[Bloo]

Also the extra tank ground is a very good Idea. I would keep it or make a new one.

 

If the grounding is lousy the gauge does not get all the way to "E" when the tank is empty.

 

The grounding through the straps or whatever can deteriorate over time and the owner usually finds out when he runs out of gas but the gauge is still above "E".

[MrY]

hmmm my carpet is glued to the floor in the trunk,

before I pull it, anyone done this before ?

I thought you have to drop the tank on a Buick 54 55 56 to reach the fuel sender

which is on the top of the thank.

All I can see in the trunk is a brown wire going down the floor to the tank sender

ie the wire that does to the dash gas gauge

I still think the float is gone or disconnect inside the tank

only way to find out is to drop the tank .......

Edited September 9, 2020 by MrY (see edit history)

[Ben Bruce aka First Born]

I don't know about '55 but  '50 the tank must be dropped. Not a difficult job.  Sender is probably bad. Readily available.  I attach a ground wire [ 12ga] to one screw of the gauge sender and the other end to the body or frame somewhere.

 

  Ben

[DFeeney]

Hello,  Drop the tank, Remove the sending unit and hook it up to a ohm meter.  According to  the other comments it should read 30 ohms  on one end of the swing and 0 on the other with a smooth transition between up and down.  This is not rocket science.  Good Luck

[Century Eight]

What he said!

[edinmass]

Why? 
 

King-Sealy! Pre war joke......👍

[alsancle]

9 hours ago, edinmass said:

Why? 
 

King-Sealy! Pre war joke......👍

 

In fairness,  if the King was around it could read full too (while empty).

[ojh]

Before I drop the tank I connect a rheostat to the wire going to the gauge and connect it to the ground at the tank, then I see if I can operate the gauge.  I want to see the gauge work before I drop the tank.  I made a tester just for checking gauges and the circuit.

When the wire is disconnected, the circuit is open and the gauge could read either full or empty depending on which way its spring pulls the needle.

Edited March 24, 2021 by ojh
after thought (see edit history)

[JamesR]

I presume the OP has come up with some sort of resolution since Sept., but I've been doing ok with just fuel logs on two of my cars for the last 15 years (no new senders available back when I had the tanks refurbished.) Of course, you have to verify what kind of fuel mileage your car gets before you rely on the log. Oh, and it helps keep track of when you added MMO or Stabil.

[Century Eight]

If you undo your ground wire and the gauge goes to full, the gauge is working.   If you hook everything back up and it reads E, most likely you have a bad sending unit.  

 

I have had a “50 Buick for 46 years and had to deal with this.  Changing a tank is not bad.  i am an untalented, somewhat spry 72 year old and have done it many times.  It gives you a chance to paint where you cant see or usually get to and maybe coat the inside of the tank.  Hopefully your car is not a northern rust bucket like some of the ones I have owned.

 

With the wonderful quality ethanol gas we buy these days, you will find your sending unit is nothing but rust from all the moisture  in the so called gas we put in the tank.  You can get the unit rebuilt,  but as cheap as they are, you can get a new one from Bobs, CARS, or maybe Kanter.   When you put it back together,  as someone here or on another forum said, put a second known, good ground wire to the frame.  You might want to be sure there is no rust or new paint inhibiting ground between the tank and the straps when it goes back together.  Also, splurge and spend three extra dollars and buy some stainless steel screws for when you put your sending unit back in, where it fits into the top of the tank. You’ll realize how smart you were if you ever have to pull the sending unit out again and the old screws didn’t rust to the tank or have the slots wallowed down.

 

Ten bucks at Harbor Fright will get you a nice little suction pump for when you want to drain the tank in case the drain plug is rusted solid to the tank.  Beats the taste of gas.  If you are able to lie down on the ground and get back up, then you can do this job.  If you’re going to hook up a rheostat, then you could get this started.  Worst part is either getting the rusty tank straps unhooked or unscrewing the screws on top of the tank that hold in the sending unit, that i think you should replace with stainless.   I can even wiggle the neck of the tank out from under  the car without jacking it up.  

 

Getting ready to do it again, this time to my ‘40.  Ugh.    But at least I wont have to top off every one hundred miles or say my fuel pump just quit when someone comes to rescue me.

 

 

[Bloo]

5 hours ago, ojh said:

Before I drop the tank I connect a rheostat to the wire going to the gauge and connect it to the ground at the tank, then I see if I can operate the gauge.  I want to see the gauge work before I drop the tank.

 

I agree, but in this case MrY said:

 

On 9/8/2020 at 8:48 PM, MrY said:

When ignition turn off - then the gas pointer diapers

When ignition turn ON - the the gas pointer goes to E (empty)

When I go in the trunk and disconnect the brown wire that comes from the tank sender - then the gas pointer goes quickly to F (full).

I have found the ground wire and ran a long wire direct to negative on battery but still stuck on E

and I cleaned the ground surface the wire/bolt from tank negative taps into the frame but still stuck on E

 

GM gas gauges from the beginning of electric gauges until sometime in the 1960s (it varies by model) were 0 Ohms empty and 30 ohms full. The fact that he is stuck on E and can make it go to full by disconnecting the wire at the tank leaves zero doubt that there is a problem in the tank. It also suggests that the gauge and wiring are probably fine.

 

20 minutes ago, Century Eight said:

Ten bucks at Harbor Fright will get you a nice little suction pump for when you want to drain the tank in case the drain plug is rusted solid to the tank.  Beats the taste of gas.

 

Just don't buy their red plunger pump. It's horrible. They have others.

 

20 minutes ago, Century Eight said:

Also, splurge and spend three extra dollars and buy some stainless steel screws for when you put your sending unit back in, where it fits into the top of the tank. 

 

That will work. Another possibility is purple Loctitie on the threads. It is low strength and made for small screws. The corrosion can't really get going if the threads are full of Loctite, however steel screws could rust at the tip where they stick through and that could cause difficulty getting them back out even if the threads are prevented from getting stuck. I would use Loctite even if I was using stainless or brass screws. It prevents gas wicking up the threads, and you WILL smell that in the car. It also lets you decide how tight to make the screws to not clobber the gasket, with no worries about whether they might vibrate loose.

 

Edited March 24, 2021 by Bloo (see edit history)

[JACK M]

Put the ground wire under one of the sender screws, Wouldn't hurt to put one on the tank itself too.