Fuel tank and gauge update and ideas needed

[ram250098]

So here is where I am at. New sender new voltage limiter new fuel tank.
Now I used some jumpers and hooked the new sender up to the wire from the tank and the fuel gauge operates as it should. Put sender in new tank and hooked up my meter set to 200ohms and moved the float up and down with a stick and it reads correct.
Took meter set to 12volts and checked blue wire I am getting power 0 to 6 volts...I know it works as I checked with the fuel sender out of the tank and the gauge worked.
Install tank in car hooked everything up and even put on a few extra grounds with some jumpers one to the sender itself to ground and another from the tank to the body..both tested good grounds.
Turn on the key and nothing the gauge only moves a hair...and I mean a hair!
This is the same problem before all the new stuff..what am I missing here.
AL

 

[Beekeeper]

I'm guessing that you put gas in the new tank?

 

[ram250098]

Should have around 8 gallons

 

[Beekeeper]

Have you checked the ohm reading of the sending unit since installing the tank
and adding fuel? You could check the gauge and wiring again by grounding the sending unit wire at the tank to ground. Only ground long enough to see a deflection on the gauge if left too long it will burn up the gauge. If the ohm reading
Is somewhere between 10 to 72 ohms (should be around 35) and you get a deflection on the gauge by grounding the sending unit wire to ground all that's left is the sending unit ground

 

[ram250098]

Checked sending unit before installing it in the tank all good, even hooked it up to the gauge and it worked. So have power to it... good ground...gauge works...WTF..I am at a complete loss.
AL

 

[Beekeeper]

Have you checked the ohm value of the sending unit since installing the tank and adding fuel?

 

[ram250098]

No I have not..what would that tell me?
Thanks
AL

 

[Beekeeper]

Well if it tested good dry in and out of the tank with a good ground
the only thing that has changed is you put fuel in it. Let's see here maybe the float is stuck or not floating if want to try to get to the root of the problem it's a process
of elimination. And also these new repop sending units are know to be inaccurate

10 ohms full
24 ohms 1/2
72 ohms empty

 

[themechanic]

Did you repaint your dash frame? I read that a lot of peolpe have electrical problem in the dash after they repaint the frame. The dash frame is the ground for the gauges.

 

[ram250098]

I had the dash out already and added a good ground there as well..the fuel gauge does work when tested with the sender manually
AL

 

[65-440]

Funny, im have the exact same issue. new tank, sending unit and fuel lines. Gas gauge works, limiter was changed a few months back and is still working. 10 gallons in the tank and the gauge barely makes it to the "E" mark .....

 

[hunt2elk]

Funny, im have the exact same issue. new tank, sending unit and fuel lines. Gas gauge works, limiter was changed a few months back and is still working. 10 gallons in the tank and the gauge barely makes it to the "E" mark .....

Welcome to the wonderful world of repopped sending units lol. I have thrown more than one in the dumpster after getting so frustrated with not being able to get them to work properly.

 

[Dennis H]

There are 3 people here who claim they have a gas gauge that works. Welcome to the club for the rest of us.

 

[Matrix2]

X3, exact same experience, but mine goes up to a quarter. Can anyone tell us who makes the best repop sending units?

 

[Icecobra]

I experienced this exact problem and after lots of measuring and testing here is what I came up with. The newer senders swing path is not correct. New tanks as you add fuel the fuel spreads across the tank and begins to climb. Unfortunately as it rises it finally picksup the new sending unit. As the new sending unit begins to climb its arc is setup to at the top of the swing read full. At this point I can tell you my sending unit did stick down on initial installation used a camera to get in the tank and bump it to get it to rise. I discovered that when fuel is full to the point it runs out the filler tube there is still an air gap in the tank. And consequently my gauge only made it to about 2/3 full. So I reached in with the camera and pushed up the float the rest of the way and gauge showed full. So I think somewhere in china someone told a guy to make a sending unit for a tank and he did not allow for the fact the tank is never full to the top. I solved the issue on my sending unit by slightly bending down the float arm unit so when it reaches 2/3 of a tank (full) it will reach the top of its arc and now my fuel gauge reads full.. I did take measurement and figure as close as I could and now when my tanks full my gauge shows full +++ and as I use fuel it goes down the about right amount. I tested my theory and as I added fuel in 5 gallon increments my gauge went up 1/4 1/2 3/4 full so I know im good to go......

 

[ram250098]

I have done many senders to many to count and this is just weird..why would the sender work outside the tank but not inside..float is good not leaking..even put in another sender and same deal.
Maybe time to try another fuel gauge..hope I have one kicking around!
AL

 

[dpstark2]

Just adding to the pile here, but maybe the wiring in your car has a high resistance between the gauge and the sending unit. If it has even 10 ohms in that line your gauge will read very low. You'll still the 0-6V signal at the end of the wire, but any current going through the wire will drop that way down and cause your gauge to read low. If this is for your 66 Coronet, you have at least one connector inline with the signal behind the driver's kick panel. There will also, of course, be the connection to the gauge panel itself.

 

[bigmanjbmopar]

Is the float on the sending unit plastic or brass? have you made sure it has no leaks and is 100% airtight? my first one had the plastic float what a joke. brass ones OTB will not be perfect so float it in gas or water what ever to check it submerge and look for bubbles.

On a side note, if you have to you can adjust the sweep on the gauge itself. there are cogs on the back of the gauge that allow you to adjust the overall empty stop or full stop.

So here is where I am at. New sender new voltage limiter new fuel tank.
Now I used some jumpers and hooked the new sender up to the wire from the tank and the fuel gauge operates as it should. Put sender in new tank and hooked up my meter set to 200ohms and moved the float up and down with a stick and it reads correct.
Took meter set to 12volts and checked blue wire I am getting power 0 to 6 volts...I know it works as I checked with the fuel sender out of the tank and the gauge worked.
Install tank in car hooked everything up and even put on a few extra grounds with some jumpers one to the sender itself to ground and another from the tank to the body..both tested good grounds.
Turn on the key and nothing the gauge only moves a hair...and I mean a hair!
This is the same problem before all the new stuff..what am I missing here.
AL

 

[ram250098]

I cleaned the plug at the kick panel..thing that has me stumped is the guage reads fine when I had the sender hooked up before it went into the tank..checked sender inside the tank and it moves freely..float I know is good checked that as well.
I did what Beekeeper said and checked the ohm reading at the tank is it was 57ohms so maybe it is the fuel gauge itself..will pull the cluster and see whats going on.
AL

 

[dpstark2]

If it read 57 ohms, your sending unit is only reading ~1/4 tank. That aside, check the resistance of the line with the sender attached at the connector behind the kick panel. Ground your meter to the dash frame or whatever ground you added to your gauge cluster. If that differs from what it reads directly at the sender, you have a wiring problem. Repeat the measurement from the gauge cluster connector while you're pulling that out. Best to check it all now before swapping gauges.

Sorry it's giving you so much trouble, but it sounds like you have the combination of the poor quality repop units and some wiring issues. Many of us have been down that road... Gauges also don't hold calibration for 45 years, so that's a factor to consider.