GAS GAUGE--ADJUSTABLE? PICS/PROCEDURE ADDED

[Dan]

In another thread it was mentioned you can adjust the gas gauge, if so can anyone chime in with how?

I just replaced my sending unit and it seems to be working fantastic, but when I filled up the tank the gauge pretty much topped out at just slightly above 3/4 full. So is there and adjustment I can make to calibrate it?

If not, any suggestions?

Thanks!

[HIO Silver]

Not really. The best you can do is to bend the arm until it reads relatively close to the actual fuel level.

Have you ever taken the sender apart? There is a tab connected to the float arm inside the lil housing. The tab "wipes" against a winding of resistive wire which feeds back the amount of resistance to the fuel gauge. What typically happens is that the windings are bunched up against each other or are not evenly spaced.

[robroy]

'evening Dan,

I had the same symptom. Crude as it may sound, I ultimately fixed it by bending the arm that the sender's float snaps in to, slightly downwards (to make the float have a higher altitude, relative to the sender's sensor). I did this with a full tank of gas, while eyeballing the gauge read-out. 'been happy with the gauge's read-out ever since, at all tank fill levels.

Before that fix, I was concerned that electrical gremlins in the in-cab/aux tank selector switch (or other wiring) were influencing the gauge's read-out, so I bypassed all that by running an alligator clip directly from the sender to the gauge. I was surprised that it made no difference (which seemed to suggest that the stock wiring was OK). That's when I decided to bend the sender's "wand." I'm not sure whether this sort of bypass test would be easy or meaningful for you, since I forget exactly how the factory instrument cluster's wired.

EDIT: HIO Silver, I didn't notice that your post preceded mine until I'd already clicked "Submit." Sorry; 'didn't mean to come across like I was ignoring your (great) post in my reply.

[crazyhorse]

Mr Dan all the above is good advice.

Here is a little more information that might be of help to you.

Read ALL the pages .

http://www.fordification.com/forum/view ... e&start=30

[HIO Silver]

'evening Dan,

I had the same symptom. Crude as it may sound, I ultimately fixed it by bending the arm that the sender's float snaps in to, slightly downwards (to make the float have a higher altitude, relative to the sender's sensor). I did this with a full tank of gas, while eyeballing the gauge read-out. 'been happy with the gauge's read-out ever since, at all tank fill levels.

Before that fix, I was concerned that electrical gremlins in the in-cab/aux tank selector switch (or other wiring) were influencing the gauge's read-out, so I bypassed all that by running an alligator clip directly from the sender to the gauge. I was surprised that it made no difference (which seemed to suggest that the stock wiring was OK). That's when I decided to bend the sender's "wand." I'm not sure whether this sort of bypass test would be easy or meaningful for you, since I forget exactly how the factory instrument cluster's wired.

EDIT: HIO Silver, I didn't notice that your post preceded mine until I'd already clicked "Submit." Sorry; 'didn't mean to come across like I was ignoring your (great) post in my reply.

No problemo. We're in sync with out response.... so it must be true, right?!!

[robroy]

No problemo. We're in sync with out response.... so it must be true, right?!!

Yes--a vote of two's an irrefutable foundation for FORDification's top Bumpside logicians to build upon (until the end of time).

[Dan]

Thanks all for the advice and the very informative link...I had no idea the "3/4 full when 100% full" syndrome was a common problem.

I know my old sending unit was bad, so replacing that was needed anyway, I think I'll try seeing if I can make the voltage adjustment outlined in the thread link, while having the sending unit outside of the tank so I can easily see what it reads at full and empty as I adjust the voltage.

Bending the float arm will be my next option if the voltage adjustment doesn't work. Showing 3/4 at full doesn't bother me as much as showing 1/4 full when empty would, so I'll see if I can make the volt adjustment.

The only other gauge I have on mine is temp which has never worked since I owned it, and I installed volts/temp/oil aftermarket gauges for that anyways, after reading the post about all the gauges being affected by the voltage, i'm kinda glad I have the aftermarket set!

I'll try to post some pics after I try this out, may be a few days before I get time though. Thanks again!

[Dan]

Ok, I finally got time to try this procedure on y truck and am happy to report it worked perfectly. Since many of the pics from the old thread that was suggested to me, have disappeared, I thought I would add new ones from my process here in case anybody else wants to try this.

First I had to completely take out the dash cluster, disconnect the speedo cable and the main wiring harness so I could access the back of the cluster, no way was this going to happen with it installed. Here below is what my voltage regulator looks like behind the gas gauge on my '67 Ranger:

I found it impossible to make the adjustment with the other 2 wires on the regulator, so I popped both off each time to adjust the little adjustment thing in the upper left.

Here's a close up of the adjustment thing, I'm not kidding when I say I tried 7 different needlenose pliers before I found one that fit and would turn the stupid thing, it's small and looks to be made of soft material so be sure you have a solid grip before you wreck it. I made 1/4 turns and would test after each 1/4 turn, to test I would reattach the 2 wires to the regulator, then put the cluster loosely back in the dash and reattach the main wiring harness.

I then pulled my gas tank sending unit out (put a rag in the tank hole, no explosions here today!) and would hold the rod in the "full tank" position, turn the ignition key on and check gas gauge.

I repeated this process many times, in the end I made almost 1 full clockwise turn of the adjustment to get it to read where I wanted. Here's what "full" is on my truck now (previously full was only 3/4 on gauge)

I think you should also check "empty" at the same time you test, here's what my sending unit read on the gauge with me manually testing it

So now I know what totally full and totally empty are per the sending unit, and I didn't have to bend it at all. after I put everything back together, I went to the gas station and filled it up full, and it read exactly as it did in my testing, so I am VERY pleased with the results.

It took me about 2 hours, but keep in mind I had just installed a brand new chrome Dennis Carpenter bezel and lens so I had to work slow and careful with everything I was doing so I didn't scratch the new bezel. It was well worth the effort though, because I can fully trust my gauge now. Hopefully this will help others, because not in a million years would I have figured out on my own that the gauges were adjustable this way, thanks to all here as always for the great advice!

[robroy]

'evening Dan, thanks for the great photos. That's really interesting; I didn't know they were adjustable.

[crazyhorse]

Mr Dan congratulations on a job well done.

Thanks for the good pictures and information.

In the process of you being helped you are helping others.

This is what makes Fordification so great, all of us helping each other.

[motzingg]

COOL

this project has been kicked to the back burner several times. I should tackle it. Very nice description.


I think the deal with the sending unit is that they make the same one for many different gas tanks and someone on the assembly line was hand-bending them to each particular vehicle. Just a guess but i wouldn't be surprised.

[lennyp]

I have a question. Did adjusting the voltage regulator effect any of your other gauges, (oil pressure and temperature gauge)?
I"d like to try this but was curious if it effected your other gauges. Thanks

[Dan]

I wish I had an answer for you, the only other gauge my dash cluster has is TEMP, and it didn't work at all when I bought the truck so instead of fixing it I installed a 3 gauge set of aftermarket gauges TEMP/OIL psi/VOLTS because I wanted accurate readings on those.

My truck just has dummy lights for VOLTS and OIL on the dash. I did read through all the related threads though and it seems that everyone else who made the adjustment, DID see increases in their other gauges, apparently the regulator is for the entire dash not just the gas.

They indicated that ALL gauges went to "normal" levels when the adjustment was made, so it seems like a worthwhile thing to try. My advice would be to take a picture of all gauges at whatever is currently "normal" before you make any adjustments, that way you have an accurate starting point to compare to as you go. I take pictures of everything I do in the garage these days, amazing how helpful and easy digital cameras can be to any project.