#1 priority - Shag and Red's fuel gauge's

[cmayna]

I thought Red's gas guage being off by 25% was annoying, until I drove Shag this past weekend.  I'm not going to go into boring details at this time as we all already know how crappy the repro sending units are but I can't let this continue on without getting it resolved. I just need to ensure that I have driven the cars enough to have 4-5 gallons left over and the necessary cans to store this remaining fuel.

I did the following post back in April but obviously never did anything about it. Nevertheless it is good reading, especially the link that Rick (Fast68back) supplied.

http://www.stangfix.com/testforum/index.php/topic,6085.msg73253.html#msg73253

[Kats66Pny]

One of these days I need to adjust Gerts fuel gauge. I'll probably just deal with it until I install the dash cluster with original gauges and not aftermarket autozone ones that are in there now. For a while, it was stuck on 1/4 tank regardless how much or little fuel there was. Got to checking things out, and seems something on the outside of the sending unit was unplugged, so plugged it back in and it works now. Only thing is it is WAY off. Full tank the needle is as far as it can go... like a couple inches past the F line. When it gets to 3/4 tank, I know I really have 1/4 tank of gas. It is annoying, but atleast these days I know how much gas I have and that is good enough for me right now!  :lol

[RustyRed]

One of these days I need to adjust Gerts fuel gauge. I'll probably just deal with it until I install the dash cluster with original gauges and not aftermarket autozone ones that are in there now. For a while, it was stuck on 1/4 tank regardless how much or little fuel there was. Got to checking things out, and seems something on the outside of the sending unit was unplugged, so plugged it back in and it works now. Only thing is it is WAY off. Full tank the needle is as far as it can go... like a couple inches past the F line. When it gets to 3/4 tank, I know I really have 1/4 tank of gas. It is annoying, but atleast these days I know how much gas I have and that is good enough for me right now!  :lol

Sounds to me like you have an issue with the float in the tank.  Like something restricting it from going below a certain level.

[AzPete]

Kats problem sounds like the auto meter gauge with the stock sender........swap the gauges and it might work better.

Craig.....you going to bend the arm? I need to do that on the '66 too. It never reads full and starts to drop fast. E = 4 gals.

[cmayna]

Pete,
First I'm going to check that the float doesn't have any pin holes and then reconfirm that the path of the arm is vertical.  Then I might simply add a couple resistors as discussed in the other post to see if I can get 4 gallons to read 1/4 tank.

Or as you mention, I can after reinstalling the sending unit put in 4 gallons.  If the gauge reads lower than 1/4 tank, bend the arm downward a little to cause the arm to come up a little.  All I know is that it will not be a fun project.

[AzPete]

Typing this response as a first from a Kindle....sitting at the doctors....

The four gal. deal takes about three drain and fill sesions. A real pain. I will attempt mine when the weather cools. Did the last one without a dain........at least now the tank has a drain.

[Fast68back]

I keep telling myself I'm going to adjust mine, just havent done it yet. I think I will pull the tank when I do mine. I was also thinking about picking up an electric fuel pump to speed up the process...

[cmayna]

I'd like to find a used 16 and 20 gallon tank that someone is upgrading from so I can practice tweaking the sending unit's arm.

[sigtauenus]

That was a great link from Rick for the Autometer gauges.

I suspect many of us have the same problem with the repro sender and stock gauges.

I'm thinking since this is such a problem, and its such a PIA to fix, that a "test bench" fuel tank could be make.

Set up a used gas tank with the top cut off or at least a 12" or so hole cut in the top.  Insert the fuel sender and gasket.  Hook up a known good fuel guage with a 12V source and the 5v? voltage regulator.  Reach into the gas tank and swing the arm from full to empty and verify gauge matches.  Bend arm to adjust gauge reading.  Verify gauge intermediate graduations by pouring in 2 or 4 gallons of gas at a time.  If any adjustments need to be made, you can reach in the top and make them without having to drain the gas.  If the full range of the gauge reading does not match the graduations, you can choose which side of the gauge to have the error on, ie, to have full be full and know you have a buffer when you get to empty, or choose to have E mean E and have the gauge be off at the 3/4-F range.  You could probably replace the drain plug with a petcock to easily refill your gas container and start over.  A key assumption is the calibration of the known good fuel guage.

The question is, which stangfix member wants to set this up and let everybody send their fuel sender to him to be adjusted?

[66gt350]

If you got 20+ mpg, then you wouldn't have to worry about what your gauge said...  :craz

[cmayna]

Sam,
I'm calling around some local Mustang shops looking for used tanks just to do that.


Rob,
Shut TF up buddy   :rp   :lol

[Fast68back]

Sam,
I'm calling around some local Mustang shops looking for used tanks just to do that.

Call Mustangs Plus, tell them you'll do a write up for their tech articles...

[Midlife]

If your gauge has an offset that's reasonably constant, you can adjust the constant voltage regulator to make the gas gauge read closer to being correct.  On the back of the CVR is a small trim pot, usually surrounded by epoxy.  Break the epoxy and rotate the trim pot until your gauge reads correct. 

For example, I run a couple of tanks to get an estimate of my mileage.  I then fill the tank, and note the miles.  When I believe I have four gallons left, I adjust the CVR so that the fuel gauge reads 1/4 full.

This is much easier than getting your arms, nose, and hair full of gasoline.

[AzPete]

As long as the system is stock.....

[cmayna]

What is the voltage going into the gas gauge?

[AzPete]

Thru the CVR, it should be around 5 volts. If after market, 12 volts.

[daveSanborn]

The question is, which stangfix member wants to set this up and let everybody send their fuel sender to him to be adjusted?

Since you've volunteered...... when you swing by my house in mid-October remind me to give you the fuel tank I have stashed away in the shop's attic.

[sigtauenus]

Since you've volunteered...... when you swing by my house in mid-October remind me to give you the fuel tank I have stashed away in the shop's attic.

I'm glad you mentioned that, I was actually going to ask if you had one...

On an unrelated note, do you still have a handfull of hog-rings left?  I'm doing the rear seat upholstery soon.

BTW, that's coming up soon, you still good for Sunday the 17th?

[cmayna]

I have some hog rings.

[sigtauenus]

I have some hog rings.

I have some left from the front, I need to look at the existing seat upholstery and count how many I actually need.  It shouldn't be that many.

[68EFIvert]

I just got done ordering a resistor from Newark.com that the guy in the post on the other thread suggested getting.  I guess I will wire that in and see if it helps.  The resistor will be about $1.18, shipping will be much more than that though.  I'll let you guys know how it works out. It sounds like a much easier solution than dinking around with gas and the sending unit.  I guess I find out though.

http://www.newark.com/ohmite/43f180e/resistor-wirewound-180ohm-3w-1/dp/64K8918?Ntt=64k8918

[garner67]

I just got done ordering a resistor from Newark.com that the guy in the post on the other thread suggested getting.  I guess I will wire that in and see if it helps.  The resistor will be about $1.18, shipping will be much more than that though.  I'll let you guys know how it works out. It sounds like a much easier solution than dinking around with gas and the sending unit.  I guess I find out though.

http://www.newark.com/ohmite/43f180e/resistor-wirewound-180ohm-3w-1/dp/64K8918?Ntt=64k8918

You got my attention.  I'm looking forward to your results.

[daveSanborn]

I'm glad you mentioned that, I was actually going to ask if you had one...

On an unrelated note, do you still have a handfull of hog-rings left?  I'm doing the rear seat upholstery soon.

BTW, that's coming up soon, you still good for Sunday the 17th?

The gas tank is used and is now yours.

Hog Rings.... I had about 900 leftover, but sent them to Rick (fast68back) when he was doing his seats.  I believe he may have forwarded the remaining balance onto another StangFix'er when he got done with them, not sure, but I don't have any anymore.

Sunday the 17th is still good for me!

[sigtauenus]

Craig,  I have a used tank here that I got from Dave, I'm going to copy your set-up for calibrating the sender.

When I first filled up my car the fuel gauge shot up to F, then as a I drove it the level dropped quickly.  I wasn't sure if I had really bad mileage or if the gauge was off.  Yesterday I saw the gauge was right at 1/4 so I stopped at the corner gas station and topped it off, it took all of 5.8 gallons to put the needle back up on the F. 

I'm thinking if I bend the arm up some, it may result in the gauge showing full longer than it is actually full, but as we discussed previously, if it is close to being on at 1/2 or more significantly 1/4 then I am ok with that.  I would really like for 1/4 to mean 4 gallons so I know I'm near the bottom of the tank and how far I have left to get gas.

[68EFIvert]

You got my attention.  I'm looking forward to your results.

I just put the resistor in and the gauge appears to be more accurate.  It read empty when I started and after the resistor was put on it read close to 1/4 of a tank.  I will have to take the car down to fill it up to make sure but my initial impression is the gauge is much more acccurate.  I just swapped headers so the car is running open exhaut.  A trip to the gas station will have to wait for a trip to the exhaust shop.  Nothing like setting the timing on a car with open headers on Xmas!