Speaking of gas gauges, again!

[Roadcuda]

We all know the fun many of us have had getting our gauges to work properly. To date I've tried several things and spent way too much money trying to get mine to work. The last time we tried to get the thing right we put an OEM sending unit in and it still didn't work. The guy thinks that the problem may be the gauge itself. Well today I went to a car show that was about a 200 mile round trip. The car ran great but what really annoyed me was that fact that the gas gauge did move from showing completely full the whole trip and two fill ups. I got to thinking, how hard would it be to install an auxiliary fuel gauge under the dash somewhere, at least until I find a new gauge and feel like trying to pull the cluster out of the car? I know that the wiring harness from the tank to the dash runs behind the kick panel on the drivers side so it wouldn't be too hard to connect from there. What do you guys think? Thanks

 

[Jim S.]

I'm just throwing this out there, before you buy a new gauge I would pull that wire off the sending unit and check to make sure it is not shorted to ground. Also check the pin it plugs into at the sending unit. 10 ohms full and about 90 ohms empty. Since you are reading full all the time, the gauge is seeing a short to ground on that sending unit wire. Granted the gauge itself could be toast and shorted internally. You have probably jumped through all these hoops before but, I was thinking that if that wire going to the gauge is shorted to ground somewhere other than at the gauge, a new gauge will read full also unless you run a new wire. Other than that if you want to run a new (different) gauge without pulling the cluster, I don't think it would be too hard. Make sure the sending wire is not shorted to ground when you disconnect it behind the kickpanel, hook it to the new gauge and supply power to the new gauge.

 

[earlyrides]

I finally got mine to work and be accurate!!!

DANG!!!
This made me crazy since my 6BBL bird can really eat some fuel but I finally got all of the bugs worked out.

I have a standard dash first of all so my fix for the dash side will only apply to that.

My gauge would sometimes work and sometimes not. Mostly it would work on cold moist mornings. Then later when it would warm up outside; it would drop to below "E".

Also when I would top off the tank on the working days; my replacement sending unit from Quanta products would only read 3/4 of a tank.

So one day while I was cruising through the swap meet at the Spring Fling Mopar show I scored a standard dash cluster for $10 bucks. (WHOOHOO!!)
As I stared at the back of my swap meet dash cluster I noticed that the fuel gauge had 2 nuts that made the connections to the circuit board. That is when it occurred to me that maybe these nuts were just a bit loose or maybe there was a bit of corrosion on the units on the dash in my bird.
So I went out to the bird. I disconnected the battery. (VERY IMPORTANT!!) Then I very carefully reached up behind the dash and felt my way by braille until I located the 2 nuts. Then I put my socket on my flexible nut driver and turned each nut back and forth a few times in case it was corrosion and went an extra 1/4 turn in case it was loose. Once I reconnected the battery and turned the key on, BINGO! And you know what? The danged thing has worked everyday without fail ever since.

Now, for the sending unit calibration. When I emptied the tank of fuel and had the key on my gauge would be about a 1/4 tank below "E" at the bottom of the sweep. So I grabbed the tool that I had purchased from Quanta product to remove the locking ring. (this isnt the only way to get the locking ring off but it is by far the easiest if you have to go in and out with the sending unit.) Once I had the sending unit on the bench I took the cover off of the resistance wire and sweep arm to see what was in there doing all of the "magic". Well heck; it was just a small brass arm pressed onto the metal arm that holds the float. So I gently persuaded the brass arm about 25% up the sweep and reassembled the cover and re-installed the unit. This time with the tank empty and the key on the gauge went just a hair above the "E". DANG! I went a bit too far. So out it came again to back off my adjustment. The next time I tested it with the tank empty and the key on it came up to one needle below the "E". I figured this was good so I would always know that even on the "E" line there would still be a bit left to get to the next "drinking fountain" for the car. Next I put in one gallon and tested it. To my surprise it came up about a half needle. Then I added 2 more gallons and it came up above the "E" mark.
So after many years of wondering if I was going to run out if I didn't keep putting in $30-$40 bucks every time I took the bird out, now I cruise with confidence knowing the "E" really means "Enough" to get to the next gas station and that every time I turn the key on that my gauge on the dash was working.

I hope this helps someone out there experiencing the same thing I was. Since then I have done the same with my 70 Bird, the 69 Vert Bird, my 68 Satellite wagon and my 66 Coronet too. And they all work great.

 

[Basketcase]

out of all the old mopars I've owned, only my first, '73 road runner had a gas gauge problem. the gauge mounting nuts bit is a great idea.

early love the hood shot

 

[Roadcuda]

Thanks Early, I'll try the idea of the nuts on the gauge. My Garage always has some moisture in it so the corrosion could be part of the problem. I was already thinking that might be causing another problem I had yesterday. It was charging intermittently. One time I was looking at the auxiliary gauge as I hit a big bump in the road and it started charging again! So I thought I should check all the connections for the charging system!

 

[jays69bird]

Honestly my gauge has always worked,that said I don't trust the gauges on any old car,when they get to 1/4 tank I top off the tank,just a good habit to get into. I have a 93 Volvo I use as a beater since my F250 gets lousy mileage,gas gauge has never worked,I used the trip meter.LOL

 

[Roadcuda]

I guess you're lucky that yours has always worked Jay. I have to admit that the gauges in both of my Barracudas do work find. AFAIK, they have the original sending units in them. It's just the after market one in the RR that want's to be a pain. I usually fill up at about 1/2 a tank. Even though I know that I end up spending the same over time it just doesn't seem that way filling at 1/2. Early, what size socket did you use on the nuts on the gauge? I found that a 5/16th and a 11/32 were either too small or too big!!

 

[Basketcase]

Steve I just tried one of my spare clusters, it's 3/8"

 

[dobie]

I tried a secondary fuel gauge last year.....It still didnt work for me. The gauge was a new after market one from Summit that tested fine out of the car. Once hooked up, it was just as incorrect as the factory gauge. I ended up removing it and connecting the factory gauge back up.

 

[69hemibeep]

I don't think the POT meters are the same as the originals. I used an OHM meter and set empty on my work bench then into the tank with the filler neck off so I could see the float to make sure it was on the bottom and still OHMed empty. Then I put everything back together The Dash showed empty and went up about a Quarter with each 5 gallon bottle of gas I put in. The only problem is that it reads over full when filled

 

[Roadcuda]

Steve I just tried one of my spare clusters, it's 3/8"

Thanks Dave! I tried that and it didn't seem to fit either but I will try again. I wasn't having much luck getting my hand up in there! And Bob, that helps also. It may explain why Steve didn't have any luck with the extra gauge. Thanks. FWIW I think all my cars show over full when filled up.

 

[Big John]

Check the float too. I had one that leaked and filled with gas. It always read low.

 

[moparmonk]

Ditto on the cracked float (or anchor, as in my case). I am really kind of surprised that no one mentioned the ground strap here. Don't forget that the tank has an insulation (ie isolation)pad and a rubber o-ring that keeps the sending unit from leaking. The fuel line has the small rubber line hooked to the steel fuel line of the sending unit that does not conduct current very well. A ground strap is the 6-8 inch piece of steel that connects the car and sending unit together. With it missing, generally they will read empty (high resistance) but since you have issues, check to make sure it is there. It is a great place for corrosion. Use a 99 cent clip lead to troubleshoot it!
http://www.ebay.com/itm/Mopar-Fuel-...unner-Dart-Duster-/230843842227#ht_1317wt_957

 

[Basketcase]

I've had a couple cars that didn't even have the ground strap, and my gauge still worked fine.

 

[Jim S.]

I was under the impression the Steve's gauge was reading full all the time. If that is the case a quick test would be to disconnect the wire at the sender and turn on the ignition key. If it reads empty, the wire and the gauge are probably O.K. Short that wire to ground and it should read full. A more true test would be to connect a 100 ohm potentiometer to the sender wire and ground. Rotate it through it's range and see if the gauge follows. At any rate, if the the gauge reads empty with the sending unit wire disconnected, it is probably the sending unit. Maybe the float has stuck in the up position or the internal potentiometer in the sending unit is toast and always reading a very low resistance similar to ground.
I realize that grounding has always been a problem with these sending units but, if the gauge is reading full, the sense wire is seeing ground. Maybe even when it is disconnected (which would indicate a short at the gauge or wire).
Not trying to confuse anyone here just trying to help. Remember these pics from awhile back addressing the grounding issue (which I do not think is the problem here) Just thought I would post them in case somebody has a gauge that reads empty all the time....................Jim

 

[Roadcuda]

As far at the ground goes when I installed it I used some wire and screwed it direct to the body after cleaning a bare spot at the connection point, and then I used a small hose clamp to fasten it to the sending unit. When I was at the guys shop working on it we did the bench test with the sending unit and all seemed good. But it didn't work right when it was installed in the tank. :brickwall: That is one reason he thinks it may be the gauge itself.

 

[A31PKG]

I've posted on the corroded gauge lug/circuit board/nut issue before...it's a good point to bring up, and VERY common. Jim's potentiometer idea is really cool. Assuming all connections/wiring etc are clean tight & undamaged, if the gauge does not read incrementally with the potentiometer, then the gauge is likely the issue. I've seen potentiometers at Radio Shack...they're cheap. Let us know how the aftermarket gauge works out Steve, if that's the way you go - it will at least confirm your theory of the gauge being bad.

 

[dhansen_69RR]

Hello to all fellow Roadrunners So I just completed my front end suspension project and waiting on a new gas tank. The gauge works fine already and kind of scared to replace the sending unit if its reading correctly. I just want to put a new tank in because the other one is so beat up. Any words of advise before I start taking the old one out? Thanks

 

[69hemibeep]

Use the old sending unit if its good

 

[Basketcase]

if it ain't broke, don't fix it.