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HELP!!! 70 Body fuel gauge won't work!!!

Posted By: Anonymous

HELP!!! 70 Body fuel gauge won't work!!! - 09/13/08 06:52 PM

This thing is wearing me out .........It should be working, but it isn't.........Here's what I've done;

If I ground the wire back at the tank, it pegs the gauge...........so I know everything from the wire to the gauge is fine..........

It's a brand new sending unit with a good float.......If I have it out of the tank with the fuel gauge wire hooked up and a wire attached from the sending unit to the body for a ground, the gauge works perfect.......With the float all the way down, it shows empty, with the float about half way, it shows half full, and with the float all the way up, the gauge shows full.........

With the sending unit out and on my table and the float all the way down, it shows 82 on my resistance setting of my meter.......With the float all the way up, it shows 13.........With the float roughly in the middle of it's travel, it shows roughly 38........

Right now, I've got about a half a tank of fuel in it........If I put the sending unit in the tank, the gauge won't go above an 1/8 of a tank, even if it's full of fuel........I hook up my meter and it reads 42, so it should be working.......I've checked and double checked to make sure the sending unit is grounded properly when in the tank and it is......and yes, there is a ground wire from the engine to ground........

What am I missing???
Posted By: TJP

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/13/08 07:33 PM

Silly questions????
Any chance you have the wrong sending unit????
Or is something limiting the travel of the float arm when installed????
Step back and look at the problem,
sounds like the solution is probably staring you in the face but your not seeing it, not trying to be a smart a-- but rather help

Tim
Posted By: Anonymous

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/13/08 07:48 PM

Quote:

Silly questions????
Any chance you have the wrong sending unit????
Or is something limiting the travel of the float arm when installed????
Step back and look at the problem,
sounds like the solution is probably staring you in the face but your not seeing it, not trying to be a smart a-- but rather help

Tim



That's what I keep thinking..........It has to be right in front of me but I can't see it.......

I found a pic of the sending unit in the Year One catalog and it looks correct by the pic......I even made sure it's touching the bottom of the tank........and with the unit in the tank with a half a tank of fuel in it, my meter shows it's reading about halfway......

It's a new tank.........and the float moves easily when out of the tank.......even if I hold it sideways a little.......I even made sure that it's indexed correctly while in the tank.......

This thing is kicking my butt.........
Posted By: therocks

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/13/08 09:57 PM

Put it in and attach a good ground to it.If its not grounding good it wont work right.I run a 12 gauge wire to the body and attach the other end with a tiny hose clamp to the sender outlet tube.I dont have a lot of faith in the factory ground that they came with.Rocky
Posted By: blairboy3

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/13/08 10:13 PM

I was thinking the same thing. Doesn't matter if it's grounded to the tank, needs to be well grounded to the chassis.
Posted By: rss

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/13/08 10:21 PM

Here's vote number three for you having a bad ground when the unit is installed. Add another ground from the body of sending unit to a good ground on the car body and see if it changes anything. I had to use a supplemental jumper ground on mine to get it to work correctly.

Good luck
Posted By: Anonymous

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 12:12 AM

I'll give it a shot.......All it has is a new stock grounding strap.......I used my meter and touched the black lead to the stock grounding strap and the red lead to the sender connector and the meter reads right, but maybe it's not enough of a ground???
Posted By: badchallenger

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 12:45 AM

There is also a possibility that the float arm might be lose and if lifted up buy the gasoline it would pull the needle on the rheostat away and not making contact. This is very doubtfull though. i would guess its the ground also.
Dave
Posted By: Anonymous

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 01:39 AM

Quote:

There is also a possibility that the float arm might be lose and if lifted up buy the gasoline it would pull the needle on the rheostat away and not making contact. This is very doubtfull though. i would guess its the ground also.
Dave



I'd thought of that too, so I took it apart and bent the needle to it hits the rheostat harder........
Posted By: JohnRR

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 04:48 PM

Welcome to the world of replacement fuel senders , I don't know of any that work properly ...

Wayne , what it he resistance between the sender body and ground with your ground strap in place ?
Posted By: Anonymous

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 05:35 PM

Quote:

Welcome to the world of replacement fuel senders , I don't know of any that work properly ...

Wayne , what it he resistance between the sender body and ground with your ground strap in place ?



It reads .8 on my meter.........and that's with an additional wire that's clamped to the sending unit and bolted to the frame..........and it still doesn't work........
Posted By: RapidRobert

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 05:53 PM

I would temporarily run a long jumper wire from the sending unit metal body DIRECTLY all the way up to the batt neg terminal.
Posted By: Hotwheel

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 06:40 PM

I have exactly the same situation with my 70 GTX. Ive done all the same trouble shooting and fixes, still will only go half way up when the tank is full. I spent many hours trying to figure out what I missed and just said the heck with it, really pisses me off though.
Posted By: minivan

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 06:42 PM

When I had redline rebuild my gauges they called me for the ohm measurements on my sending unit and calibrated my gauge to the sending unit.
Posted By: Anonymous

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 08:21 PM

Quote:

I would temporarily run a long jumper wire from the sending unit metal body DIRECTLY all the way up to the batt neg terminal.




I just got back from doing that and it's still the same......

Quote:

When I had redline rebuild my gauges they called me for the ohm measurements on my sending unit and calibrated my gauge to the sending unit.




What I don't get is, with the float out of the tank, a ground wire clipped from the sending unit to the fuel sender ground strap, it works perfect........I can move it from empty, to half way, to full, and the gauge reads right...........

It's as if the sender being in gasoline is causing the problem......
Posted By: JohnRR

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 10:01 PM

Quote:

Quote:

I would temporarily run a long jumper wire from the sending unit metal body DIRECTLY all the way up to the batt neg terminal.




I just got back from doing that and it's still the same......

Quote:

When I had redline rebuild my gauges they called me for the ohm measurements on my sending unit and calibrated my gauge to the sending unit.




What I don't get is, with the float out of the tank, a ground wire clipped from the sending unit to the fuel sender ground strap, it works perfect........I can move it from empty, to half way, to full, and the gauge reads right...........

It's as if the sender being in gasoline is causing the problem......



Wayne I did a tongue in cheek back and forth with someone else recently on this EXACT SUBJECT and I asked this question which I got no reply to .

How do you know that the level you are raising it to is the actual level its going to inside the tank when its full of fuel ?
Posted By: HealthServices

Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 10:42 PM

Quote:

Quote:

Quote:

I would temporarily run a long jumper wire from the sending unit metal body DIRECTLY all the way up to the batt neg terminal.




I just got back from doing that and it's still the same......

Quote:

When I had redline rebuild my gauges they called me for the ohm measurements on my sending unit and calibrated my gauge to the sending unit.




What I don't get is, with the float out of the tank, a ground wire clipped from the sending unit to the fuel sender ground strap, it works perfect........I can move it from empty, to half way, to full, and the gauge reads right...........

It's as if the sender being in gasoline is causing the problem......



Wayne I did a tongue in cheek back and forth with someone else recently on this EXACT SUBJECT and I asked this question which I got no reply to .

How do you know that the level you are raising it to is the actual level its going to inside the tank when its full of fuel ?



  • In other words what reading are you getting?

  • Remember your tank is only 12" tall or so and long and wide.

  • This means that if the car is jacked up in the rear the fuel will move to one side and the level in the tank will be off.

  • Also you may have to bend your float arm so when the car is level and half full of gas the guage will read the same.

    • Posted By: Anonymous

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/14/08 10:56 PM

    Quote:


    How do you know that the level you are raising it to is the actual level its going to inside the tank when its full of fuel ?



    All I do know is that with my ohm meter, I can check the reading at the sender while in the tank and it reads roughly halfway.......about 42 on my meter..........

    Quote:



  • In other words what reading are you getting?

  • Remember your tank is only 12" tall or so and long and wide.

  • This means that if the car is jacked up in the rear the fuel will move to one side and the level in the tank will be off.

  • Also you may have to bend your float arm so when the car is level and half full of gas the guage will read the same.





    • I have the car on my drive on, 4 post lift, so the car is sitting just as it would be on the ground......

    I've also bent the float arm so it would make the fuel gauge read even higher (which I've done in the past on different cars and it's moved the needle to where I've wanted).........

    It kills me that with the sender out of the car and hooked up, I can move it through it's travel, and the gauge works correctly!!! That keeps me thinking it's a ground problem, but I think I've eliminated that by running a heavy gauge wire from the sender to the battery!!! Where's the head bangin' the wall emoticon???
    Posted By: JohnRR

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 12:33 AM

    It might be partly a ground problem as .8 ohms isn't really 0.

    any idea what the original sender read when it was at half a tank ?

    how do you know what you have in the tank is actually half a tank ?

    I'm not sure what my Dart has for a sender , my tank is painted on the outside , but when I fill it , the fill nozzle shuts off and spits fuel down the side of the car , it only reads 3/4.

    I have a new sender , 3/8 line , and I have a new sender for my Bee also , I am NOT looking forward to replacing the senders .
    Posted By: Anonymous

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 01:23 AM

    Quote:

    It might be partly a ground problem as .8 ohms isn't really 0.

    any idea what the original sender read when it was at half a tank ?



    What's odd is, I can use that exact same ground wire, attached to the sender with it out of the car, and it works!!!


    The guy brought this car to me like this.......

    Quote:


    how do you know what you have in the tank is actually half a tank ?



    When I'd found that the float had a hole in it and was full of fuel, I'd installed a new float and filled it up with fuel.......On the way home the gauge slowly worked it's way up to the half way mark........so I figured I'd drain some fuel, bend the float lever to make the gauge read higher, and then reassemble........I drained 6 gallons out from full and that's just below the bottom of where the sender goes in.......so I know I'm 6 gallons from full.........

    Quote:



    I'm not sure what my Dart has for a sender , my tank is painted on the outside , but when I fill it , the fill nozzle shuts off and spits fuel down the side of the car , it only reads 3/4.

    I have a new sender , 3/8 line , and I have a new sender for my Bee also , I am NOT looking forward to replacing the senders .



    I've been down this road before, a bunch of times.....and have never had one get the best of me..........
    Posted By: RapidRobert

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 02:36 AM

    how about taking some thin metal parts tag wire & wiring the float/arm up to the upper stop & installing it this way. If it still reads "full" when you get it in there & hooked up then the only thing left is the liquid level in the tank isn't high enough for that particular sender or the tank isn't getting filled as much as you think & you could dunk the sending unit in a bucket of water outside the car with the ground & hot leads hooked up & see how it acts which would let you reach down & move the float thru its range of travel.
    Posted By: Anonymous

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 03:10 AM

    The thing is that the sender needs to be in the lowest position to be able to get it back into the tank......

    I had thought about putting it in bucket of fuel to see if it reads any different.......
    Posted By: RapidRobert

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 03:39 AM

    Quote:

    The thing is that the sender needs to be in the lowest position to be able to get it back into the tank...... I had thought about putting it in bucket of fuel to see if it reads any different.......

    You might bend the steel fuel line part enough so that it will go in & then bend it back later. I would not think doing 2 large radius bends would cause any fatigue issues. We got to get to the bottom of this but I think dunking it might be informative.
    Posted By: Anonymous

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 04:22 AM

    What stinks is that this sending unit is stainless......so it's a PIA to bend........I know that because I tried to bend it a little to make it lay on the very bottom of the tank........
    Posted By: charger RTSE

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 12:31 PM

    Ive had two floats crack and fill with fuel the stainless sender units are very tight where they hold the float.Id say your float is hitting the top of the tank before the guage reads full.Both of my senders read 3/4 when tank is full their driven me mad.I mucked around with my spare sender unit the other day and found they need to be adjusted at the full stop tang to get a full reading you have to bend it were it comes out of the sender unit.I now get a full reading out of the tank while i only ever got 3/4 full.And then you have to then adjust the empty float hight.
    Now im worried i might have the same problems as you as the float probably will hit the top of the tank through its travel.I will have to measure the travel the float will need from empty to full.
    If its more than the hight of the tank im done with fuel guages i will just have to remember ive got 1/4 tank when showing empty.Good luck with yours.
    Posted By: Anonymous

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 04:11 PM

    I just filled it up with fuel and went for a test drive.......The gauge goes to halfway and that's it.........this is even after I've bent the float arm down so it'll make the gauge read higher......
    Posted By: RapidRobert

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/15/08 08:09 PM

    I'd submerge it in a large bucket of water & check it & my only remaining idea is, that the tank isn't getting all the way full. It's grounded, the float isn't waterlogged, the rheostat functions... Do you believe in Karma, curses, voodoo, or good old fashioned Murphys law any of that sort of thing.
    Posted By: dg_dodge

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/20/08 11:11 AM

    Anyone have a picture of how that ground from the sending unit should look like? Where on the unit and chassis are the best places to put this ground wire? I need to do this for my new unit as well. Thanks !!
    Posted By: stumpy

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/20/08 02:28 PM

    Here's the stock ground strap. It goes from the metal line coming out of the sender to the metal fuel line. It bridges the rubber hose. You can do the same thing with a piece of wire and two fuel line clamps.

    Attached picture 4698403-3001855188928080_8.jpg
    Posted By: dg_dodge

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/20/08 03:04 PM

    Thanks much for that. I didn't know there was an actual grounding strap (mine doesn't have one).

    Does anyone have a picture of this (or the wire) installed on their car?

    As far as metal lines from the sending unit, I have two - the 3/8 for the fuel and the 5/16 for the return. Does it matter which one is grounded?

    Thank you.
    Posted By: RapidRobert

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/20/08 03:12 PM

    Quote:

    As far as metal lines from the sending unit, I have two - the 3/8 for the fuel and the 5/16 for the return. Does it matter which one is grounded? Thank you.

    no. but the factory ones like what stumpy showed are for 5/16 lines so would have to carefully bend the end that is going on to your 3/8 line.They are brittle metal & works better to grab it with your thumbs & open it up a bit then slip the 3/8 line THROUGH it rather than trying to expand it further & putting it OVER the 3/8 line.
    Posted By: dg_dodge

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/20/08 10:30 PM

    Thanks guys.

    So, if I was to go with the 12 ga. wire approach as was suggested earlier, I can just use a small hose clamp to secure this to an exposed portion of either of the two metal lines from the sending unit and secure the other side to the chassis, correct?

    Thanks!
    Posted By: RapidRobert

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/21/08 12:12 AM

    Quote:

    Thanks guys.

    So, if I was to go with the 12 ga. wire approach as was suggested earlier, I can just use a small hose clamp to secure this to an exposed portion of either of the two metal lines from the sending unit and secure the other side to the chassis, correct? Thanks!

    correct
    Posted By: eagles

    Re: HELP!!! 70 Body fuel gauge won't work!!! - 09/21/08 01:27 AM

    I am not sure, but I believe it could be the ground strap that goes around the rubber lines at your tank, it has to be clean to ground properly, also they make a larger ground strap for a hemi fuel line, I have one in my garage, but I am not sure what size it is, but it is bigger than the original, thanks
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