Author Topic: Gas Gauge (Read 4665 times)

1972 Wagon · « **on:** February 23, 2017, 06:47:06 PM »

Finally had time to use pinto_one's directions to test the sending unit by running a wire from the tank plug to a ground. With the key in the On position, the gas gauge needle did not budge from its "Below Empty" position. We pulled the left rear tail light and cleaned the ground wire that attaches to the body. We checked the fuel gauge wire from where it attaches at the tank, runs over the tank to the left tail light, and then forward to the dash. The wire(s) were securely wrapped with no visible breaks. We also used pinto_one's advice and pulled the panel next to the hi- beam switch that covers the wires. We pulled apart the fuel wire connector and cleaned it. Next we pulled the instrument cluster. With the key in the On position, we used a test light on the gas gauge posts. The post that connects to the IVR made the light blink. We assume this means that the IVR is working and the gauge is getting power. When we touched the post that traces to the multi-pin connector, the light did not blink. Does this mean that the gauge is faulty? The gas gauge hasn't worked since 1994 and we would like to get it working again.

pinto_one · « **Reply #1 on:** February 24, 2017, 08:51:33 AM »

I think the gauge itself is bad , the IVR is working when you touched that gas gauge post on the back of the panel and test light blinked , the other post on the gas gauge is hooked to the tank , so if you ground that post and the gauge still does not work its the gauge , but when you do ground it you have to wait a few seconds for it to work , the reason is they have a small coil of wire wrapped around a bi metal spring , when the wire heats up the spring bends and moves the needle on the gauge , the max voltage these gauges should ever see is 5 volts , (that what the IVR is for ) I think I have a early gauge that will work , I see I can dig it up for you ,, the problem is that the old IVR is a mechaical type of unit , if one thing goes wrong in it the gas gauge will be damaged , around the 80s ford got away from that type of set up , I see quite a few other people here have the same problem and do not know where to look and how to fix it , the next thing I am planing on doing when I finish my rear end ratio change is to do a write up with photos on the pinto fuel gauge, repair and fixes with much need adjustments for correct tank readings , also the last test on the gauge it see if its any good it has to be removed , then take a 9 volt battery out of a smoke detector and jump a wire from each post of the fuel gauge , and touch the post on the battery and watch the gauge , if it does move to full remove wires , the gauge is good , if not the gauge is bad , hope this helps

1972 Wagon · « **Reply #2 on:** February 24, 2017, 11:59:54 AM »

Let me make sure that I understand how to perform the 9 volt battery test. I need to have two jumper wires. I then attach one end of each jumper wire to a different gas gauge post. Next I touch the other end of each wire to a different post on a 9 volt battery. I want to make sure that I do the test correctly. Thanks for the information on how to test the gauge. Based on the number of archived posts on gas gauges and sending units, I think that a write-up with photos on how to test each part would be very useful. I probably would never have gotten the speedometer cable off without the picture and directions that you posted!

1972 Wagon · « **Reply #3 on:** April 29, 2017, 11:10:18 AM »

Thanks to Blaine's guidance, my Pinto's gas gauge, which hasn't worked in 20+ years went from the first picture to the second picture. From the day my Pinto was new, the gas gauge always read above the Full Line. Our family knew that when the gauge said the car had half a tank, it was really on a 1/4, and if you dared to drive until the big E, you were on fumes! My brother got an instrument cluster off eBay and sent it to me. He drove our family's other Pinto- a 1972 yellow sedan with tan interior. That car hauled many surfers to the beach until he sold it and it began a second career as a racer. It is nice to have a gas gauge again. Thanks again, Blaine!

1972 Wagon · « **Reply #4 on:** April 29, 2017, 11:32:27 AM »

I should have included that we just swapped out our nonworking gas gauge with the one from the eBay purchase!

pinto_one · « **Reply #5 on:** April 30, 2017, 08:46:15 PM »

Great that you got it working , but as you know that was the problem will All pintos with the gas gauge readings , when the gauge showed half you did have a 1/4 tank and dropped fast , this week I will be posting a cure for for it with photos on how adjust and cure the high needle syndrome too , have the whole system layout on a table (wife thinks I'm nuts ) and just about done . Standby for it soon , Blaine

LongTimeFordMan · « **Reply #6 on:** May 02, 2017, 02:45:12 PM »

I solved my gas gauge calibration issue by replacing the mechanical ivr with an adjustable revulator I made from a lm317 adjustable regulator and a 1000 k pot that allowed me to adjust the supply voltage to the gas gauge.

I connected the pot to the regulator with about 1 ft of wire to allow it to hang just below the instrument cluster so I could calibrate the gauge.

Turns out that my gauge requires 5.2 v to read correctly.

The parts cost less than $10 and I bought some from amazon for $8 for 10 pots and $6 for 10 lm317.

I calibrated my gauge by adjusting the gauge to read about 1-1/6 inch above full.

Measured voltage.

Drive car till gauge read 1/2, filled tank.. should take 6 gallons, if not make small voltage adjustment.

Drive to gauge reads 1/4, at this point I drained tank by disconnecting fuel line to fuel pump and using hand pump / siphon emptied tank.

Added 1 gallon back to tank, noticed gauge , no change, added another gallon, no change, added another, 3 total gauge read between empty and 1/4,

Added 1 gallon, adjusted voltage so gauge read 1/4,

Added another gallon 5 total gauge read between 1/4 and 1/2.

Added another gallon total 6 gallons, noted half full gauge reading and voltage. About 5.2 v

Filled tank and gauge read just past full. Drove till gauge read 1/2, filled tank and it took 6 gallons.

Your readings may vary, but I chose ttlo calibrate to full and 6 gallons at 1/2 gauge reading, noting readings as lower levels.

I have some extra pots and regulators i can send if anyone wants to try this and will try to to a write up with photos when i have time.

The main difficulty with this mod is that the mechanical regulator has terminals similar to a 9v battery that mates with connections on the circuit board.

The LM317 regulator has 3 terminals, input, output and reference. The cluster circuit board has a connector like a 9 v battery for the input and output and the case is the ground.

heres a photo of how to wire the regulator... Sorry I dont have info on how to connect to the existing circuit board on the cluster because i rewired my cluster completely because my circuit board was deteriorated.

someone will need to check the connections on the circuit board connections at the place where the mechanical IVR connects to determine the proper connections... once that is known you shold be able to use the connections from a 9v battery connector to connect to the circuit board..

Wittsend · « **Reply #7 on:** May 03, 2017, 07:44:57 PM »

Great idea. Over on my Tiger side of life they do similar (what with Lucas gauges and all). I think though, for me, I'd fill an empty tank with 2 gallons and adjust it for b-a-r-e-l-y moving the gauge. The accuracy at other points is far less important (to me) than being close to the point where you know are going to run out - but still have a reasonable reserve. I have a Valiant that is dead on accurate and have learned the hard way with that car there is no "secret" reserve.

Now, with my Turbo Pinto I used the gauge cluster (Including gas) from the Turbo Coupe. The TC tachometer is where the Pinto gas gauge use to be. And, sadly a full tank only reads 1/2 full with the mix/match sender/gauge.

LongTimeFordMan · « **Reply #8 on:** May 03, 2017, 08:29:20 PM »

Hi.. well i first started building building adjustable electronic regulators for my 68 mgb and another for my 88 Ford e350 rv.

Makes things a lot easier to calibrate.

Theres also a ford pickup site where there is a description of how to adjust the gauge. There are 2 adjusters accessable by holes in the back of the gauge. One sets the bottom point (empty) and the other sets the witldth of the swing of the pointer. The problem with setting levels lower than about 2 gallons is that the sender in the tank is usually bottomed out crom 2 gallons to colpletely empty. Thats why i set my gauge to read just above empty with 3 gallons.

pinto_one · « **Reply #9 on:** May 04, 2017, 09:27:52 PM »

These past few weeks I have been digging up parts to show some of the problems with None working gauges , how it works and fixes , and where to look, and what's inside , this might take a few postings to cover it all on repair and and parts you can still find , one common problem is that the speedometer cluster has been removed too many times , the plastic circuit traces where you unplug the unit gets all mangled up , see photo of a good one and bad one , this is what happens when you don't take care when removing the cluster , there are three major wires that must make contact here , the next one is the sending unit that goes in the tank , most of these have been in the fuel tank 40 or more years. And some have been ruined from old gas that turned to a tar base coating from years sitting somewhere, but they do make a replacement, but they do need some additional adjustment for the gauge to read right , I made a cutaway of a pinto Wagon tank from a rusty tank I had to show how far off the travel is , this will have to be adjusted with a ohm meter and some bending to center everything ,

LongTimeFordMan · « **Reply #10 on:** May 04, 2017, 09:35:41 PM »

Good info about the sending unit.. as I mentioned above I have encountered the problem with deterroriated printed circuit and mechanical IVR. If you can trace the connections to the IVR contacts, I can add info about how to connect the adjustable regulator I detailed above to replace the mechanical IVR.

As I mentioned, I rewired my cluster to eliminate the printed circuit.. Ill try to make some photos.

pinto_one · « **Reply #11 on:** May 04, 2017, 09:47:57 PM »

Now part #2 for testing I set up a early pinto fuel gauge (71 to 78) and a later 79 to 80 ) to compare , and to test the 5 volt regulator, I have the stock Ford and a aftermarket one from the parts store, these are what you call a pulsed DC regulator , inside you have a thin wire wrapped around a bi metal spring that heats up and opens and closes very fast to give an average of 5 volts , over time these will stop working and do two things , one is no power to the gauge , two is the little fine wire breaks and full power to the gauge and frying it , it too has a bi metal spring that hooks to a arm to the needle, and also wrapped with fine wire that heats up to make it move ( max is 5.5 volts or its toast )

pinto_one · « **Reply #12 on:** May 04, 2017, 09:59:31 PM »

Here is part #3 , thanks longtime Ford man on your custom electronic regulator , most you can still buy nos ones and aftermarket ones , I tryed both and you see the difference, reads way to high , that on was the after market one , yes you can adjust these , but you have to use a small pair of pliers to do so ,

LongTimeFordMan · « **Reply #13 on:** May 04, 2017, 10:17:09 PM »

Thanks for the comment. I had the same problem with mechanicals, thats why I designed the electronic...

After calibrating my gauge, i found that for my sender and gauge i needed to set the regulator to 5.2 v

Now my gauge reads 1/4 with 4 gallons, 1/2 with 6 and just past full when topped off

BUT... its VERY IMPORTANT to have a good ground to the printed circuit and to the ground connection of the LM317 circuit. Without a good ground it isnt possible to provide a reference voltage for the LM317 and the output voltage goes to 12v. I had a bad ground connection at the connector plug to the cluster and it drove me nuts trying to stabilize the oltage...

ALSO.. the metal mounting tab on the LM317 is at the output voltage, not the ground, so it needs to be insulated from ground.

After I posted my description of the electronic regulator I realized the terminals connecting the mechanical IVR to the printed circuit are the same as the terminals on a 9v battery, so that the electronic regulator can be connected to the clip on terminals on the printed circuit with a 9v battery connector readily available as well. So its just a snap in connection to the circuit like the mechanical IVR. I just need info about the connections to the IVR since I replaced my printed circuit.

Also.. it is possible to just bypass the traces on the printed circuit on the cluster and connect the electronic unit directly to power, ground and gauge.

pinto_one · « **Reply #14 on:** May 04, 2017, 10:17:23 PM »

Here we are at part #4 I opened up to show what's inside and the tiny screw for adjustment , you see the contact and small fine wires that heat it up , the contacts are closed and when you turn on the ign switch it send 12 volts and kicks the gauge moving , then the wire heats up and starts sending 5 volts pulsed to the gauge , I also check the stock regulator on the later 79 up fuel gauge , yep reads the same , but there is a better way to go like I did mine on my 76 pinto , is did buy a aftermarket electronic ready to install regulator , yes it work but very slow to start up , takes a few minutes for everything to warm up , as for calibration I also found a very handy device that cures the main what's in the tank , it's come two different ways , one if you already have the electronic 5 volt regulator and one that it's built in , it's called meter match , you can set and program the level by just pressing the save button when you fill the tank at different levels , it also has a low fuel warning light if you want to hook up that , the one with the built in regulated does not have that option , thei one is for my Wagon , and it might be a good setup for Wittsend for mismatched gauges ,

LongTimeFordMan · « **Reply #15 on:** May 04, 2017, 10:32:44 PM »

I also looked at aftermarket adjustable regulators but the one I designed only costs about $6 in parts depending where you buy them the LM317 can cost between $.50 and $5.00 and the 1000 ohm pot can cost from $.50 to $5.00 .. actually mine cost about $2 because i found LM317 for 10 for $5 and the pots for 10 for $6 on amazon.

As I mentioned above theres a good writeup on a F100 forum about adjusting the low point and swing on the gauge itself. Ill try to find it and post a link.

pinto_one · « **Reply #16 on:** May 04, 2017, 10:35:42 PM »

Guess we are on the same page, long time Ford man , they are alott of hard wired panels out there , check out the meter match site on the little box , that make one that wire go straight to the gauge terminals lugs , plug and play , also going to buy the tack match also for my cruse wagon, it has the stock factory tack in it and I want to make it work , the fuel gauge now works great , tomorrow I am going to post some wiring diagrams to help everyone trace what can be wrong and where to look , this weekend I will set up the tank mockup and show how to program the meter match box , for those that want to wire in Longtimefordma ns set up you can take the old regulator and gut it out and solder the wires to it and drill holes in the case to run the wires out to the pot , have a great one , later Blaine

LongTimeFordMan · « **Reply #17 on:** May 04, 2017, 10:52:36 PM »

Ok... just found some pix of whats inside the auge and the adjustment points

The gauge is a bimetal one activated by a heated bimetal strip, the more voltage, the more deflection.

There are 2 adjustme t points. As you can see with holes in the case to access the adjusters.

As seen from the back od the gauge the hole on the lower left sets the low or empty point, the one at top right sets swing or max deflection...

I played with these and they are VERY SENSITIVE. BEFORE ATTEMPTING ANY ADJUSTMENT, MARK THE ORIGINAL POINTS WITH A SHARPIE MARKER SO YIU CAN SET TO FACTORY SETTINGS.

Advise to experiment with a spare gauge.

LongTimeFordMan · « **Reply #18 on:** May 04, 2017, 10:57:16 PM »

Blaine... Can you maybe post a pic of the original circuit with an indication of which IVR terminal is the positive and which goes to the gauge to simplify the install for folks want to keep the original printed circuit.

Another problem I found was that in my sending unit the resistance doesnt seem to change from bottomed out to about 2 gallons, and just starts to register at about 3 gallons, so trying to calibrate below 2 gallons is pretty useless, i figure at 1/4 i have 4 gallons and at "empty" i have 2.

I could remove the sending unit and bend the float lever but didnt want to open the seal on the tank since it works otherwise.

Also, apparently the basic gauges are similar for early fords and jeeps

pinto_one · « **Reply #19 on:** May 04, 2017, 11:28:22 PM »

Sure , tomorrow I will trace it out and find out which is the hot side , after this I will open up one of the pinto gauges to see if it has the same as you posted , if you have the stock send and it works I would leave it alone , my Wagon sender was bad so got the reproduction unit , the tank mockup (cut up Wagon tank ) will help me with the ohm and arm adjustment, trying to get the max ohms because it gauge will read better , let you know tomorrow

LongTimeFordMan · « **Reply #20 on:** May 04, 2017, 11:46:36 PM »

Ive had my 73 gauge opened and it is the same as the one I posted.

As for the resistances, I have measured them.

The gauge, terminal to terminal is about 23 ohm I think.

The sender is "supposed" to be about 80 ohm at empty

And about 10 at full

But its not really linear because of the float arm geometry. Ive drained my tank, and measured resistance by filliny 1 gal at a time and found the resistance no where near linear.

I have drained tank and refilled about 6 times from 1/2 mark and adjusted voltages each time to get readings at 2, 4 ,6 and full.

The full and 1/2 were easy, just fillex tank, drove till gauge read 1/2 filled again, noted amt required to fill to full, made minor adj and repeated until at 1/2 reading it took 6 gal to refill. Took about 3 adjustments.

Then drained tank completely, added 1 gal at a time and recorded readings.. turns out 4 gal at 1/4 and 6 at 1/2.

Used fuel till 1/4 reading, filled and it took 8 gallons. So i guess thats about as good as it gets.

I had a 1968 mgb that i calibrated with an adj regulator and bending float rod and had it accurate to 0 and 1 gallon at bottom and 1/4, 1/2 , and full.

BTW I appreciate your work in posting your tips as well should help a few folks.

LongTimeFordMan · « **Reply #21 on:** May 05, 2017, 12:16:05 AM »

Heres link i found to a writeup on gauge calibration

http://www.allfordmustangs.com/forums#/topics/185611?page=1

Also heres a link to a wiring diagram for most 72 fords including pinto

http://www.gt40s.com/images/torino/72ford.pdf

The pinto section starts at pg 16.

Maybe someone knows where to post the link here so folks can search for it

As far as building the electronic regulator inside the case of the mechanical one, I thought about that but was concerned about the LM317 not getting enough air and overheating and as I mentioned above, the metal mounting tab needs to be insulated from both positive and ground, so I opted to mount it on a small heat sink and attach it to the plastic housing of the cluster with a screw.

BUT, I suppose that you could just gut the mechanical IVR and use the plastic base with the contacts, mount the LM317 leads to it and just let it hang there open without the original IVR case.,

LongTimeFordMan · « **Reply #22 on:** May 05, 2017, 12:55:04 AM »

So Pinto_One.. are you comming to the stampede in dearborn this year?

pinto_one · « **Reply #23 on:** May 05, 2017, 10:34:16 AM »

No, cant make it to dearborn this year , maybe if it was alittle closer , will get the positive side of the regulator for you when I get home , here is the link to where i brought my electronic regulator from , http://dennis-carpenter.com/instrument-cluster--voltage-regulator/p/D1AZ-10804-A/, and the link to the gas gauge meter match , http://www.technoversions.com/MeterMatchHome.html .

pinto_one · « **Reply #24 on:** May 05, 2017, 05:41:51 PM »

Here is the connections for the regulator , left side goes to power , the right side goes to the gauge and the tab on the bottom is ground , later Blaine

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Author Topic: Gas Gauge (Read 4665 times)