Ok my fuel gauge isn't working right, and since the the filler neck seal was leaking l desided to pull the gas tank. I pulled out the sending unit (which looks pretty new) and test the resistance. It read about 67 ohms empty and about 9 ohms at the full level. The other gauges seem to be working properly so I think the dash voltage regulator is working good. I then hooked up the sending unit and dry tested it and here's what I found.
Set at empty the needle disappears.
When set at full the needle moves but seems to hit a mechanical stop right before the E.
Could mean the needle is in the wrong position?
Thanks Cody, I've seen that video, it was a great help, it got as far as I got to this point.
I don't want to have to pull the dash apart if I don't have to, but it looks I might be forced to. If I do can anyone tell me how to inspect the gauge itself?
Before you take the dash out... Go to radio shack & pick up a few resistors.... Disconnect the wire from the sending unit & use a resistor between that wire & ground... 10 Ohms should register a full tank... 90 ohms should register an empty tank...
You should be getting a pulsing power signal through the sending unit lead with the key in the run position.... With an old analog gauge you should read about 5-6 volts... A digital gauge reads to quickly & you'll have a tough time getting a usable reading because the IVR pulses the power to lower it to the 5-6 volt range... 50% duty cycle = 50% of the full voltage...
Quote from: 1 Wild R/T on May 17, 2017, 04:29:45 PM
Before you take the dash out... Go to radio shack & pick up a few resistors.... Disconnect the wire from the sending unit & use a resistor between that wire & ground... 10 Ohms should register a full tank... 90 ohms should register an empty tank...
Since I checked the resistance of the sending unit it's that doing the same thing?
When needle raises it comes a very hard stop you can actually see it bounce a little when it does like the travel is being mechanically limited
Is there a ground strap between the sending unit and the fuel line?
Quote from: shawge on May 17, 2017, 05:11:49 PM
Is there a ground strap between the sending unit and the fuel line?
Yes, when I ran the test I made sure it had a good ground. The needle moves so it's get a signal.
Sounds like the gauge is broke. It should sweep smooth and not have any hiccups or get stuck. :dunno:
That's pretty much what I'm thinking. One thing I did notice is that the gauge needle disappears (see 1st photo ), when I was looking at replacement gauges the needle rest on E. Do you think it's possible the needle is out of position?
Maybe? :huh: It should be seen all the time and not disappear. :alan2cents:
Quote from: Valkman on May 17, 2017, 06:18:20 PM
That's pretty much what I'm thinking. One thing I did notice is that the gauge needle disappears (see 1st photo ), when I was looking at replacement gauges the needle rest on E. Do you think it's possible the needle is out of position?
I agree, something is wrong with the gauge. It sounds like something has slipped out of place. The needle should not disappear and it shouldn't hit a stop in that position.
Quote from: RUNCHARGER on May 17, 2017, 06:42:30 PM
I agree, something is wrong with the gauge. It sounds like something has slipped out of place. The needle should not disappear and it shouldn't hit a stop in that position.
Agreed... But the sender is out of proper range too... 67 Ohms means when your out of fuel the gauge will be reading close to 1/2 tank...
Aren't the Mopar gauges calibrated for 70 - 10 ohm?
Quote from: shawge on May 17, 2017, 08:53:58 PM
Aren't the Mopar gauges calibrated for 70 - 10 ohm?
Actually 73-10........ I was thinking of Ford which is 90-10.... Sorry old & simply wrong...
Yes, there is a ground strap from the sending unit to the body fuel line.
Do I have to remove the whole instrument panel to access the front of the gauge?
Yup, it's really not hard... Remove the six screws holding the light panel above the cluster... I usually just swing that over the top & lay it carefully on the pad... Now find the weakest masking tape you own... Mask the face of the dash on either side of the split between the light panel & the main bezel.... This prevents the all to common scratches on the face of the bezels... A/C car? If so remove the duct below the steering column... Loosen the three 1/2" bolts at the base of the column that attach the plate to the firewall.... Next take the two 7/16" nuts & washers securing the column to the bottom of the dash... this will allow the column to drop... There are five screws securing the top of the bezels to the upper dash & five or six screws at the bottom of the dash bezel right down by the radio & heater controls.. They hide in little square recesses on the bottom of the bezels.... Once those are all removed the bezels should be loose, the switch panel comes out first & unplugging the wires can either be done from below the dash or by shifting the bezel enough to get your hand behind it to unplug stuff.... Pay attention but the plugs only go on one way... After the switch bezel is out the main bezel rolls out & down.. Next four screws secure the cluster to the dash frame... Before you roll it out lay a towel over the column, this prevents scratching the dash and/or the column... Reach behind the cluster & unplug the speedometer cable, it has a tab/lever that you push down the pull lightly & the cable slides off..... While the dash is out lube the cable... Now you can roll the cluster face down onto the column & disconnect the wires... Take the cluster to the bench...
Excellent tutorial Randy: I might add if you can find a fuel gauge and get it restored you might want to do that before pulling the dash down. Just so you don't lose use of the car for awhile or have to do it twice.
Quote from: RUNCHARGER on May 18, 2017, 07:51:40 AM
Excellent tutorial Randy: I might add if you can find a fuel gauge and get it restored you might want to do that before pulling the dash down. Just so you don't lose use of the car for awhile or have to do it twice.
Good point... From all reports the repo gauges are junk so find an original & have it restored...
Thanks Wild R/T!
Quote from: Valkman on May 18, 2017, 09:23:44 AM
Thanks Wild R/T!
Hey, I had to redeem myself for my Ford gauge specs gaff... :rofl:
Quote from: 1 Wild R/T on May 18, 2017, 10:08:43 AM
Quote from: Valkman on May 18, 2017, 09:23:44 AM
Thanks Wild R/T!
Hey, I had to redeem myself for my Ford gauge specs gaff... :rofl:
That's okay as I get older I have more brain farts as well, I won't if I could take something for that?