Gas gauge calibration unit

[68gtxman]

Heh, LOL. I'm not the guy who found this. I don't remember who, or I'd thank 'em. Someone else posted that thing some time ago in one of these threads. Please LET US KNOW how this works, 'K?

Sure thing, but please don't hold your breath. I have a lot of "to do's" this summer.:-({|=

 

[RustyRatRod]

So then this is something that remains permanently wired into the circuit?

 

[KitCarlson]

Yes it needs to remain, if you want it to function. It works in a similar fashion to the one I designed. It actually has the same wired connections. The actual circuit and means of adjusting calibration differs.

 

[67Dart273]

Yup. It's programmable. If the gauge "halfway works" but is just somewhat out of cal, and if the sender "halfway works" as in the popular non-accurate repop units, you can program these units to drive the gauge higher or lower as required.

This is sort of like the modern electric speedos in modern cars. Somewhere, buried in the expensive dealer crap, is a utility to re-program the speedo, which, really, is just an electric meter display of some sort.

 

["Dart67"]

Someone had posted it on this board, but I don't remember where or who...........

I posted on this originally.

Here is the link to my update: http://www.forabodiesonly.com/mopar/showthread.php?t=275117

Herb

 

[67Dart273]

!!!THANKS!!!! Dart67. That is where I saw this.

I'm just going to quote you right into this thread...............

http://www.forabodiesonly.com/mopar/newreply.php?do=newreply&p=1970417694

[quote="Dart67";1970417694]I came across this tonight while looking for replacement Non Linear Fuel Sending Units for our MOPARs.

http://technoversions.com/MeterMatchHome.html

I am going to call them Monday and will more then likely order one.

Sure looks like promising solution/fix for all of the mismatched Factory dash gauges and Aftermarket Linear (instead of non linear) tank sending units.

The unit is a little pricey, but if it corrects the dash gauge readings it would be worth the cost.

Herb[/quote]

[quote="Dart67";1970460907]I have now installed this device.

Here is a discription of my setup.

"Home-Brewed" aluminum fuel tank. Just short of 18 gallons.

Tank is 10" deep ans is basicly the same shape as a stock tank.

The Fuel sending unit in the tank is also "Home-Brewed".

It is made from a "universal" gauge mounting unit which is adjustale up and down for depth.

The "sender" portion is a non linear (73 - 10 ohm) unit from a late model a body with the float arm length increased for the extra tank depth.

The dash gauge is a Autometer Sport Comp II short sweep (73 - 10 ohm) unit.

SO, nothing is even close to factory

With that said, This little device dose seem to work fairly well.

It has four correction points.

Low (empty)

Low Mid (somewhere between 1/4 and 1/2 tank)

High Mid (somewhere between 1/2 and 3/4 tank)

High (full)

I have both empty and full set pretty much dead on.

Half tank is now real close.

!/4 and 3/4 are "close" but not right on.

I set the readings with the tank on the floor with extension wires to ground and the sending wire to the front.

I added "WATER" 1 gallon at a time to the desired depth and then set each point with the Meter Match.

Again, to be fair, I do not know how well this would work with a stock tank and the "aftermarket" LINEAR sending units.

I would think that it would offer a pretty good correction.

Herb

i have now installed this[/quote]

 

[RustyRatRod]

Yes it needs to remain, if you want it to function. It works in a similar fashion to the one I designed. It actually has the same wired connections. The actual circuit and means of adjusting calibration differs.

Thanks. It makes more sense to me now.

 

[68gtxman]

Thanks to you too Dart67!

 

[Pawned]

This is what happens when I doubt myself. I brought the cluster inside to see what was happening with the gas gauge. I check it out and then in total frustration I ordered a MeterMatch from his website.
So for the last couple days, while waiting for the metermatch to arrive, I started putzing around with the gas gauge/cluster. I graphed out voltages, resistance and current flow at the gas gauge. I played around with the gauge adjustments and voltage input to the gauge.
Well, to keep it short, I somehow stumbled across the almost exact setup for the gas gauge. While it sits on the test bench. I am using an exact sending unit. I marked the sending unit to F 3/4 1/2 1/4 E.
Here is my dilemma, do I put the cluster back into the car as it sits or should I install the MeterMatch and be done with it.



Ed

 

[desmo900]

I'd install the Metermatch and be done with it.

 

[Pawned]

I'd install the Metermatch and be done with it.

You are most likely correct, I think I will put it in without it just to see how I did. The next time I pull the cluster (which very well may be the same day) I will use the metermatch

 

[Pawned]

For the umpteeth time I put the dash cluster back in the car. On the work bench I got the gas gauge really close. Even thou the MeterMatch is sitting on the computer desk here looking at me. I had to give the gauge one final chance to work properly.
I filled the tank about 8 miles ago, so it still reads Full. It would read off the gauge past full as it usually does, but I put in a stop at the full mark so it will be there for quite a while.
I did spreadsheets, charts and graphs each time I adjusted the needle. As soon as I got settings that were almost linear from E to F I used that. I think, If it does not work this time, meaning giving me a good reading when it is coming on Empty, I will put in the MeterMatch. The problem with the MeterMatch it gives a digital read out. There are only 4 set points so the needle will jump between settings like a digital readout. So if my modification works I will have an analog sweep from F to E

 

[67Dart273]

Well, don't forget that there's actually several things that could be wrong with the gauge unit. It could no longer be anywhere, for lack of better word, 'as linear' as designed, it could have intermittent sticking in the mechanical mechanism, etc

 

[KitCarlson]

I do not understand the 4 setpoints, that seems ridiculous. Even the one I built has a maximum of 255.

 

[Pawned]

I do not understand the 4 setpoints, that seems ridiculous. Even the one I built has a maximum of 255.

You turn the rotary switch for the points you want to set High Calibration point, mid-high calibration point, Mid- low and Low calibration point.

So when the sending unit hit a certain resistance it will go to one of 4 positions that you set.
So a person would be smart to make all 4 set points between 1/2 and empty.

Like I told you before, I would be interested in trying out your build and see how that worked. Although I am hoping the adjustments I made before putting the gauge in yesterday will work better than I had tweeked it before and I will not need this MeterMatch at all.
The MeterMatch will be available to have here for other problems I can not fix

 

[Pawned]

You turn the rotary switch for the points you want to set High Calibration point, mid-high calibration point, Mid- low and Low calibration point.

So when the sending unit hit a certain resistance it will go to one of 4 positions that you set.
So a person would be smart to make all 4 set points between 1/2 and empty.

Like I told you before, I would be interested in trying out your build and see how that worked. Although I am hoping the adjustments I made before putting the gauge in yesterday will work better than I had tweeked it before and I will not need this MeterMatch at all.
The MeterMatch will be available to have here for other problems I can not fix

I am using the car a little and the gauge is traveling from Full to 1/4 properly. I still have a couple gallons of gas in the trunk. Waiting to see where the gauge will be when it runs out of gas.

I will keep you informed. I have not drove the car very much lately so it may take a while

 

[Pawned]

I am using the car a little and the gauge is traveling from Full to 1/4 properly. I still have a couple gallons of gas in the trunk. Waiting to see where the gauge will be when it runs out of gas.

I will keep you informed. I have not drove the car very much lately so it may take a while

I took the Duster out for a spin. The gas gauge was about 1/8 of a tank. So when I could see the pin and E mark touch, I stopped and filled it up. I was nervous as I was on the freeway. I did not want to stop to to put gas from the can in once it ran out.

The gauge read zero and I filled it up with 8 gallons. About 1/2 a tank. So this is telling me that I still have room for physical adjustment to the gas gauge.

 

[Pawned]

I bought an instrument cluster yesterday. As filthy as it looked, was as nice as the 3 gauges. I brought out my power supply and gas sending unit. and hooked them up.

The gas gauge works 100% to spec. Straight 5VDC
I am now convinced that, without the Meter Match unit I have, the gas gauge can not be calibrated. Period.
So now I am going to put in the gas gauge I got yesterday. I am totally convinced that if it does not work properly, I will be looking at the wire from the sending unit and the gauge. Maybe that has been altered by whatever unknown reason.

 

[67Dart273]

There is no doubt that senders are a huge problem. "Redline gauges" or whatever his name is recently posted someone he claims is one source of "good" senders. I'll try and find the post.

 

[Pawned]

There is no doubt that senders are a huge problem. "Redline gauges" or whatever his name is recently posted someone he claims is one source of "good" senders. I'll try and find the post.

I am very certain that my sending unit is good. It measures the correct resistance at the points it needs to be. I have no concern about the sending unit. I tested the one in the tank before I installed it.

 

[Pawned]

I am very certain that my sending unit is good. It measures the correct resistance at the points it needs to be. I have no concern about the sending unit. I tested the one in the tank before I installed it.

I finally ran out of gas and pulled the tank so I could replace the sending unit with the newer one I have as reserve. I put the gas I poured out of the tank back into the tank and then added 2 gallons of gas.

The gauge was still sitting on E. I think that should be correct. I went and gassed up the car, the gauge is sitting on F.
With the sending unit I removed, I gassed up and it was also on F, But 25 miles later it was sitting below 1/2.
With the new sending unit, it started on F and I have only maybe 10 miles on it and it is still on F. Keeping my fingers crossed, that the new sending unit and gauge that is still in spec, I think I fixed the problem. (not like you heard that from me before).

Maybe later in the week I will drive her around and hopefully see the gauge moving VERY slowly to the left

Now what am I going to do with the MeterMatch I bought? I will probably find a use for it, before long.

 

[Pawned]

I have driven the car very little since I put in the new sending gauge. Finally this morning I noticed that the gauge is just above 3/4. Looks like it finally works properly. I will keep the MeterMatch on the desk until I find a use for it.

 

[66fyssh]

Thanks for the update Pawned!

I just finished reading through the thread. Just the other day I finally got my fuel gauge working by using the 7805 regulator. It's been raining here for two days and I have haven't had a chance to take the car out to see how accurate the gauge is. It's suppose to be nice tomorrow so I'll be out burning up some gas!

It's really nice to see the gauge finally move!!!:cheers:

 

[Pawned]

It's really nice to see the gauge finally move!!!:cheers:

Well, it is down to just above 1/2 tank. Now that I realize how fast it drinks gas, I will put it up and drive my other car with better mpg