Fuel sending unit issues!

[440+6]

A way to test is to buy a couple of resistors at radio shack, a 10 ohm and a 80 ohm.
put between wire to sending unit and good ground, 10 should read full and 80 empty.
This way you know if it's the sending unit or not.

 

[red 69 runner]

I put a new one in mine,just get used to when it says empty go fill it up.I dont think you will ever find one that is correct.I got rid of the old one and it was off by a 1/4 tank.would go to 3/4 when full.the new one goes to 1/2 when full so I fill it up when it gets to empty,ussally takes 9 or 10 gallons so I am content.

 

[Garp]

Here's The Fix

What is going on:

From the time we acquired the GTX it has had difficulty displaying anything more that about 1/2 tank of fuel.

The first thing I did was replace the sending unit, purchased through Classic Industries. No change, same indications.

Next came the new instrument panel with new Autometer fuel gauge, with the correct resistance for MOPAR's. Same problem.

This week, we cleaned the area around the tank and added a ground wire from tank & from the sending unit to chassis. Same problem!

Then we ran the ground from the sending unit all the way up to the battery ground. Same fricking thing!

Now, we are contemplating another sending unit, hopefully one made in the USA rather than China....

I have seen NOS units for $200+, but they are only 5/16" units and I need a 3/8". Also found dozens of units for anywhere from $30 - $150. Does anybody know which of these is a reputable manufacture and vendor where I can get one that will work?

Also, if I have left out a troubleshooting area, please let me know...

Jeff

I think I have the solution to everyone's problem. We run into the same problems that everyone else in this forum is having. Fuel gauge would only show a partial reading no matter how full the tank was. Sending unit out of the tank would work fine and show the proper ohm readings, but get it into the tank and the gauge would show a improper reading. After three sending units and many sleepless hours, we finally took the tank out again and did some testing with a different approach. Instead of worrying about the ohms, we decided to take a good look as to what it looked like inside the tank itself. We set the tank on a table, took out the filler tube, and shined a flashlight into the tank. Just as we thought, the sending unit was above the bottom of the tank by about 2-3 inches. I'm assuming that the mounting angle of the tank was made improperly. What we did next is carefully bend the pickup tube until the filter and float were just barely off of the bottom of the tank. This is a bit of trial and error to get it right, but isn't too bad. I wish we had thought of this sooner to eliminate all of the headaches and time wasted. This cured the problem of an incorrect fuel gauge reading. It works great, now.
We ended up using a Spectra tank and sending unit. As long as the ohm readings are good out of the tank, everything should work fine after you bend the tube down.

 

[retractable]

I have had very good luck with sending fuel senders to be rebuilt to John Wolf and Co in Ohio. I had some rebuilt there a number of years ago and they worked just like the original. I just sent 3 last week to them for rebuilding. They have a 2 day turnaround. I think they will also calibrate with the gauge if both are sent to them.

 

[GTX.JCW]

Garp & retractable,

Thanks for the response to this.. Although the issues still remains, it is better since I installed a Spectra sending unit. It does need to have the float arm bent down a bit as it will not go below the 1/4 mark.

Jeff

I think I have the solution to everyone's problem. We run into the same problems that everyone else in this forum is having. Fuel gauge would only show a partial reading no matter how full the tank was. Sending unit out of the tank would work fine and show the proper ohm readings, but get it into the tank and the gauge would show a improper reading. After three sending units and many sleepless hours, we finally took the tank out again and did some testing with a different approach. Instead of worrying about the ohms, we decided to take a good look as to what it looked like inside the tank itself. We set the tank on a table, took out the filler tube, and shined a flashlight into the tank. Just as we thought, the sending unit was above the bottom of the tank by about 2-3 inches. I'm assuming that the mounting angle of the tank was made improperly. What we did next is carefully bend the pickup tube until the filter and float were just barely off of the bottom of the tank. This is a bit of trial and error to get it right, but isn't too bad. I wish we had thought of this sooner to eliminate all of the headaches and time wasted. This cured the problem of an incorrect fuel gauge reading. It works great, now.
We ended up using a Spectra tank and sending unit. As long as the ohm readings are good out of the tank, everything should work fine after you bend the tube down.

 

[mmissile]

Good money/crap parts. But we keep buying the crap, so it'll never change.

 

[ibsorgn]

Didn't read every post but I hooked up my sending unit outside the tank and operated it manually to see how the whole system performed. It all worked properly. I found my problem to be the same as GARP's.

 

[1968rick]

Garp, you hit it right on.....went thru the same thing on my 68....now gauge is accurate...my only problem is it moves too fast from full to empty.....

I think I have the solution to everyone's problem. We run into the same problems that everyone else in this forum is having. Fuel gauge would only show a partial reading no matter how full the tank was. Sending unit out of the tank would work fine and show the proper ohm readings, but get it into the tank and the gauge would show a improper reading. After three sending units and many sleepless hours, we finally took the tank out again and did some testing with a different approach. Instead of worrying about the ohms, we decided to take a good look as to what it looked like inside the tank itself. We set the tank on a table, took out the filler tube, and shined a flashlight into the tank. Just as we thought, the sending unit was above the bottom of the tank by about 2-3 inches. I'm assuming that the mounting angle of the tank was made improperly. What we did next is carefully bend the pickup tube until the filter and float were just barely off of the bottom of the tank. This is a bit of trial and error to get it right, but isn't too bad. I wish we had thought of this sooner to eliminate all of the headaches and time wasted. This cured the problem of an incorrect fuel gauge reading. It works great, now.
We ended up using a Spectra tank and sending unit. As long as the ohm readings are good out of the tank, everything should work fine after you bend the tube down.

 

[themechanic]

Just bending the arm will do that. You don't truly fix the problem; just trade it for a different one.

I like DennisH' idea of finding a gas station every 200 miles or so for a fill up.

 

[watermelon]

i ditched my mopar sender and gauge when i went fuel injection.

i had the tank out so i put in a tanksinc universal sender and autometer gauge. both are GM 0-90 ohm units. i got tired of worrying about fuels levels.

you can throw stuff at me now

 

[Charlie71rt]

I sent my date coded OE unit to Tri Starr in Seneca Falls NY. Great service, quick turnaround, ohms calibrated, 1 year warranty 129.00. I installed it yesterday reads full and empty like it should, gotta believe everything in between will be spot on as well.

 

[Fran Blacker]

I sent my date coded OE unit to Tri Starr in Seneca Falls NY. Great service, quick turnaround, ohms calibrated, 1 year warranty 129.00. I installed it yesterday reads full and empty like it should, gotta believe everything in between will be spot on as well.

What was wrong with sender? Like to know if they replaced resistor wire.

 

[Charlie71rt]

What was wrong with sender? Like to know if they replaced resistor wire.

The contact tang had a hole worn through it, and the actual failure was the rivet where the wire connects to the re

 

[Charlie71rt]

The rivet that connects the wire to the resistor had failed, I could have fixed that but when I took the cover off and found the hole in the tang I was out of my league

 

[Charlie71rt]

If I recall they said they would rewrap the resistor wire as part of their rebuild before I even sent it to them.

 

[70runner]

Another option, which doesn't require removing the tank sender, is Metermatch MM02. I worked with the manufacturer to verify his redesigned prototype would work with the RTE electronic regulator in my 70RR. Set up a bench test with the instrument gauges out of the car. Measured sender (Spectra) resistance at the gauge connector in the car for empty (73ohms), 1/2 (41), 3/4 (26), and full (15). Spec for the OE senders is empty 73ohms and full 10ohms, but it isn't linear. The MM02 has a Ford preset option that pretty much matches the OE spec. I started with that and adjusted the metermatch using an impedance box to replicate the actual sender resistance for each measurement. Now the gauge works just like it did when it left the factory.

 

[Richard Cranium]

Very simply, the repro senders suck. Everyone has problems with them.

 

[BLK 68 R/T]

The issue with the new senders is the resistance coil inside of them is the same diameter for the full length so while the empty and full will read right, anything in between is wrong due to the different resistance reading given in relation to the coil size. Original senders have a tapered coil inside so the resistance reading at 1/2 tank will be different than a new one with the straight coil.

 

[Charged440]

The issue with the new senders is the resistance coil inside of them is the same diameter for the full length so while the empty and full will read right, anything in between is wrong due to the different resistance reading given in relation to the coil size. Original senders have a tapered coil inside so the resistance reading at 1/2 tank will be different than a new one with the straight coil.

I noticed that when I compared my old one to the new POS. Sounds like the ones they use are a generic coil they just slap on there. I can't imagine that making the right one would raise the price all that much.

 

[themechanic]

Anybody use one of these?