Fuel gauge off on new tank

chuck · Jul 23, 2010

LSUpete said:
THAT is a ridiculous amount of work. You're a better man than me.

Most likely not, 3 of us worked on it on a customers dime.

chuck · Jul 23, 2010

markperry said:
Chuck, please stop taking offense too our dismay on these tanks no-body is blaming you for the inaccuracy of these tanks!

What we would like too see is, if you could offer us some resolve too our problems.....You have WOWED us with the innovative stuff you offer, just put some of your guy's on a mission too fix the problem with these tanks an sell us the solution. Everyone would PAY too resolve it, I know I would!

You have me wrong, I am not offended. I see something that is not right and correct it or try to make better understanding. yakelys69 quoted me saying I check the 1/2 tank then types that he would love to here from any vendor that checked 1/2 tank reading. I do not know him and don't know if he knew I was a vendor or what. Anyway, I was not offended just not sure what was meant. The gauges, I was not offended here either, I did not design the gauge/sender, was not even born at the time. It works O.K. if everything is right. And would be too expensive to make a precision gauge. Anyway sorry if I offended anyone it was not my intent

markperry · Jul 23, 2010

I did not design the gauge/sender, was not even born at the time. It works O.K. if everything is right. And would be too expensive to make a precision gauge. Anyway sorry if I offended anyone it was not my intent[/QUOTE]

No offense taken hear!

yakelys69 · Jul 23, 2010

Chuck yes I know your a vendor and the racers you build look awesome, I have your springs & efi tank. Love them except this part. This is where I am coming from. Autometer states that stock the 1/2 tank reading should be 25ohms and your post I quoted said that you test for 40ohms at 1/2 tank. That's a big difference, with numbers that far out of range it's not going to work rite.

Your site and the other vendors I checked do not mention the reading at 1/2 tank. That's my point. It would make things much better to include that information on your sites. I wanted to know why "the vendors" don't.

If one vendor said 1/2 tanks reads 25ohms and yours said 40ohms I would know which one to purchase to match my brand new gauge, that should be precision.

chuck · Jul 26, 2010

I don't know about autometer so can't comment on their numbers. The stock and stock replacement senders have 10 ohms when the floot is up near the top of the tank and 73 when the float is down near the bottom of tha tank. The resister wire is close to linier so the float being 1/2 up or 1/2 way down depending on how you look at it should be about 1/2 tank or 73-10/2=31.5+10= 41.5, as it turns out that number is very close to the ohm reading when you check with the float 90* to the beam. My tank is about 14" tall and we set the float at 7" which reads 41 ohms which is not truely 1/2 tank because the bottom 1/2 is not as big as the top 1/2 because of the sloop in the bottom 1/2 of the tank. At any rate that is how my tank is set up.

gddyap · Jul 27, 2010

I think my 10 year old NWMP 23 gallon tank may have a 240-33Ohm sending unit in it. At least that would make sense with what my gauge says. I'm going to drop my tank at some point to test it out. That and seal the sending unit which leaks like crazy when the tank is full. I also want to see if an E2000 pump will pull fuel through the intake pump.

yakelys69 · Jul 29, 2010

Tonight I ran some test with 2 original fuel gauges, an original voltage regulator that works prudy good and my truck battery. These are that steps I took and the results.

Connected my battery ground directly to the gauge housing
Connected the battery + to one side of the regulator
Connected the output side of the Regulator to the 1st post of the fuel gauge.
Used my volt meter to confirm the output. Using the - post of the battery and the 1st post on the fuel gauge I have a mpg movie I can post later if requested but unfortunately this site won't let me upload a mpg. :-X The results are fun. 0.05, 5.71, 8.97, 0.57, 0.01, 7.71 and randomly on like that.
Test a Resistor, see (1st picture) (24.7 ohms) just like Autometer states 1/2 tank should be. This is in contrast the the 1/2 tanks (40 ohms) that BC broncos sending unit uses.
Connected the Resistor directly between the battery ground and the other post of the fuel gauge. (2nd picture)
The result was bouncing on and just below the 1/2 tank mark! (See pic 3)
I added another resistor inline bringing my resistance to (34.4 ohms) (pic 4)
The result was just around or below 1/4 tank. (pic 5)

Keep in mind that any bad connections would only create more resistance giving a lower fuel reading.

I repeated these steps using a 2nd less reliable gauge due to a fire and the results were similar but off. 25 ohms was between 1/2 and 1/4. 34 ohms was between empty and 1/4 tank.

I don't think anyone with a bronco expects anything to be absolutely perfect but I do believe this shows the 40 ohm @ 1/2 tank sending unit is not designed properly for the bronco or autometer 10 - 72 ohm gauge.

Your thoughts?

Viperwolf1 · Jul 30, 2010

The stock senders (and gauges) are not linear. Mid scale at the sender is 23 ohms. This is directly from the factory manual.

Sounds like Chuck's senders are made to be linear which would cause low readings below a full tank with the stock gauge.

chuck · Jul 30, 2010

Sounds like, I'll look into it.

chuck · Jul 30, 2010

Well, dam-it. I set up a gauge, new sender and new solid state IVR. I found that when near full or near empty the gauge is accurate but in the meddle (1/2) not so much. With ohms 73-10, 1/2 way 43 ohms. I can't figure any way to get it to read 1/2 when the tank is 1/2 and also have the full/ empty work. I think all the aftermarket tanks use the same senders made for ford gauges but I will start looking into new senders.

JDJ · Jul 30, 2010

I am glad to hear/read that a vendor is looking into these types of issues. The attitude that Chuck has (wanting to fix the issue to provide a better product) is awesome.
I have done business with chuck before and this motivates me use Chuck over other vendors.

Thanks Chuck and keep up the good work!

J.D.

yakelys69 · Jul 30, 2010

Yep it really says a lot and goes along way.

Thanks for looking into it Chuck

markperry · Jul 30, 2010

JDJ said:
I am glad to hear/read that a vendor is looking into these types of issues. The attitude that Chuck has (wanting to fix the issue to provide a better product) is awesome.
I have done business with chuck before and this motivates me use Chuck over other vendors.

Thanks Chuck and keep up the good work!

J.D.

X2 Chuck is the man!

P.S. leave it Viperwolf too put him on the right track.....He is(the)!!!! Bronco Guru!!!!!! No offense too anyone with this status!

chuck · Jul 31, 2010

Thanks guys, I am looking but no fix yet. This is what I have found so far.

The Ford Fuel Level sensor with a 73-10ohm range operates with the following ohm ranges for Full, Half, Empty, and Below Empty:

Full: 10ohms
Half Tank: 25ohms
Empty: 50ohms
Pointer Width Below E: 73ohms

"If you have replaced the original equipment Ford sending unit in your vehicle with an aftermarket sending unit, you may notice that the gauge will match the sending unit at the Full and Empty portions of the scale, but that the readings in between will not match up. The reason for this is that some aftermarket senders operating with the 73-10ohm range now utilize a linear movement instead of the original non-linear scale. The comparative ohm reading difference for Full, Half, and Empty have been supplied below for your reference.

Full: 10ohms
Half Tank: 41ohms
Empty: 73ohms

As you can see these numbers differ radically from those of the factory Ford sending units and have a drastic effect upon the gauge readings."
That info is from autometer, their fix is to move the 1/4, 1/2 and 3/4 markings on their gauge to match the factory sender

Viperwolf1 · Jul 31, 2010

chuck said:
Thanks guys, I am looking but no fix yet. This is what I have found so far.

The Ford Fuel Level sensor with a 73-10ohm range operates with the following ohm ranges for Full, Half, Empty, and Below Empty:

Full: 10ohms
Half Tank: 25ohms
Empty: 50ohms
Pointer Width Below E: 73ohms

"If you have replaced the original equipment Ford sending unit in your vehicle with an aftermarket sending unit, you may notice that the gauge will match the sending unit at the Full and Empty portions of the scale, but that the readings in between will not match up. The reason for this is that some aftermarket senders operating with the 73-10ohm range now utilize a linear movement instead of the original non-linear scale. The comparative ohm reading difference for Full, Half, and Empty have been supplied below for your reference.

Full: 10ohms
Half Tank: 41ohms
Empty: 73ohms

As you can see these numbers differ radically from those of the factory Ford sending units and have a drastic effect upon the gauge readings."
That info is from autometer, their fix is to move the 1/4, 1/2 and 3/4 markings on their gauge to match the factory sender

Chuck,
Since you have a test fixture setup you might try using a resistor (about 160 ohms) in parallel with the sender. That would cause the lower tank readings to be higher on the gauge and have little effect on the full reading. The 160 ohm value would give an overall 50 ohms to the gauge (empty mark) when the sender is at 73 ohms. Of course this would mean the tank is empty when the gauge gets to the E and not after, but the mid scale would be more accurate. It would be an easy fix if it tests out ok.

chuck · Jul 31, 2010

I thought of that but 50 ohms will show around 1/4 tank on the gauge when you run out. But full would be full and 1/2 would be about 1/2. I don't want to hear the bitching monday morning after a customer had to walk 5 miles+ to get gas in his tank that shows 1/4 on the gauge

I think empty meaning there is a little gas left is better. Anyway I did a little testing.

Sender empty= 73 with 160 ohm = 50 with 61 ohm = 33
sender 1/2 = 43 with 160 ohm = 34 with 61 ohm = 25
sender full = 10.4 with 160 ohm = 9.7 with 61 ohm = 8.9
The gauge that I am using will read empty at 70 ohms, 1/2 at 26 ohms and full at 10-11 ohms. Doing a little math I don't thing there is a fixed resistor that can fix this. We could make a stepping resister bank that could use the sender input and provide the right amount of ohms out but would cost too much. I may be able to have the correct sender made if I can't find one. Again cost may be an issue. Or make a fuel gauge face that is scaled to read correct. I am still looking, if anyone finds one or another plan let me know.

jpopsbronco · Aug 1, 2010

Would it be possible to make a kit to modify the stock senders IE different arm set up for stock sender so you get full range of movement but still retain factory ratios? Cost shouldn't be too bad.. Just an idea. someone poke some holes in it. ;D
BTW thumbs up for chuck!

72_EB · Aug 1, 2010

Way to go, Chuck.

Glad to hear you're working on a fix. Just throwing another idea out there while you are brainstorming, how about a new gauge that fits in the original cluster that looks like factory one, but works with the linear sender? Much easier for all of us to change a cluster gauge than drop and replace senders on tanks with the skid plate. I've seen more than one crusty looking spring on stock fuel gauges and it would be nice to have all new parts that fit in the factory cluster. You could work on the other three gauges to sell as a package alongside this project (with a factory looking voltmeter to replace the bouncy Ammeter

).
Keep up the good work, Chuck! In my opinion, it is the best oversided aftermarket tank out there with your mounting system and the ability to have in tank low pressure or high pressure pump depending on carb or EFI.

JDJ · Aug 1, 2010

You da man Chuck! Keep up the good work!

backpain · Aug 1, 2010

chuck said:
. . . As you can see these numbers differ radically from those of the factory Ford sending units and have a drastic effect upon the gauge readings."

That info is from autometer, their fix is to move the 1/4, 1/2 and 3/4 markings on their gauge to match the factory sender

Hence, my earlier post in thread re: matching gauge/sender regardless of ohm range - as long as they match. Since none of it is installed yet, I guess I'll be going with the 240/33 Autometer sender and Ultra-Lite gauge. Just need to adapt the sender to BC's square plate mount.

Anyone need a new linear 73-10 sender? Still in a tank in a box.

If this doesn't work, I'm giving up and going with a sight tube and some mirrors ;D. . .

Fuel gauge off on new tank

Bronco Guru

Bronco Guru

Bronco Guru

Sr. Member

Bronco Guru

Bronco Guru

Sr. Member

Attachments

electron whisperer

Bronco Guru

Bronco Guru

Bronco Guru

Sr. Member

Bronco Guru

Bronco Guru

electron whisperer

Bronco Guru

Full Member

66to77

Bronco Guru

Bronco Guru

Similar threads