Moparts
adjusting the gas tank sender
Posted By: mickm
adjusting the gas tank sender - 07/10/08 02:04 AM
putting a new tank in, already have a new sender that has been in for a while.
the gauge would never register more than about 3/4 full, when i filled the tank. it measured past empty when i had 4-5 gallons in it.
with the sender out, i found that at the lowest point of travel it went beyond empty, and at the highest point, a little beyond full. so the gauge works fine.
so what i did was mark where the sender was at 3/4 on the gauge, and then move it up to full, and bend the float down closer to that point. but at that point, the float hits the filter, and does not go down all the way. i assume this is fine, as it probably didn't go down all the way to the stop to register empty anyway, witness my 4 or so gallons and the gauge being past empty.
does that sound right? or does anyone have any other suggestions about adjusting this correctly?
Posted By: RapidRobert
Re: adjusting the gas tank sender - 07/10/08 03:34 AM
not much help but I would want to adjust it so that when the needle hit the mark at the E the tank is ALMOST out of gas.
Posted By: GTXKen
Re: adjusting the gas tank sender - 07/10/08 01:15 PM
I have the same issue so I'll
Posted By: Mopar-Al
Re: adjusting the gas tank sender - 07/10/08 01:49 PM
This seems to be a common question asked quite often now with sending units on mopars on different web sites. I am starting to believe there is a flaw in most repros. I would also think that there should be some kind of measurment you could make a bend to for calibrations in mas produced units. Same tanks, same capacity should be same sending unit adjustments, wouldnt you thin? My repo does the same thing as with many of my friends repos. I put my old one back in with no issues.. But I wanted a 3/8ths so I am going through the hastle again.
Posted By: Fury Fan
Re: adjusting the gas tank sender - 07/10/08 04:33 PM
I recalibrated one some years ago via resistors, wired them in series at the fuel tank with the sender wire. Had to keep adding resistors in a parallel bundle until I got the right amount (lots of crawling under the car with resistors and then out to check the gauge!). After hitting the right combination I sealed it all with heat shrink. This was for installing a used OEM sender so it's not the same situation.
As I recall it was off by 1/8 tank at one end of the gauge but was close enough for me. It either read E at a true 1/8 tank or never reached full.
I recently installed a new Spectra Premium sender in another car and it's off by 1/4 tank. I think this one needs the float arm rebent. I'll empty the tank, fill it with 6 gallons (24 gallon tank) and see what adjustment needs made to put the gauge to 1/4 tank. 6 gals should be below the gasket of the sender and permit me to R&R teh sender without spilling fuel. Can then maybe hold the float to the top of the tank somehow and see how the gauge looks for full.
Posted By: Anonymous
Re: adjusting the gas tank sender - 07/10/08 05:00 PM
i hate to be the bearer of bad news but some of you guys are probably never going to get your sending units to work.
The reason is because many of the reproduction sending units were not built right. Their resistance range from empty to full was not correct. A proper guage should be 10 ohms at full and 73 ohms at empty. you will most likely find yours to a different range. I cant remember what the bad units had for a range but it was something like 0 to 100. that means at 1/4 empty, you will read empty and at full, you'll read 3/4 full
theres no way to fix this as far as i know other than to change out the resistor element to the correct one.
this is a KNOWN problem with reproductions (at least some of them)
Posted By: Anonymous
Re: adjusting the gas tank sender - 07/10/08 06:12 PM
Quote:
i hate to be the bearer of bad news but some of you guys are probably never going to get your sending units to work.
The reason is because many of the reproduction sending units were not built right. Their resistance range from empty to full was not correct. A proper guage should be 10 ohms at full and 73 ohms at empty. you will most likely find yours to a different range. I cant remember what the bad units had for a range but it was something like 0 to 100. that means at 1/4 empty, you will read empty and at full, you'll read 3/4 full
theres no way to fix this as far as i know other than to change out the resistor element to the correct one.
this is a KNOWN problem with reproductions (at least some of them)
I'm not sure I agree with that. If the repop sender has a LARGER resistance change than the old one, it should be possible to add some resistance in parallel with the sender to ground to set the range. Then, it would be a matter of adjusting the thing so that empty is correct on the one end, and adjusting the resistor for full on the other.
Frankly, I'd be happy to have "empty" fairly accurate, but the one thing you do NOT want, is for the tank to be empty before the gauge is!!
Also, don't discount the possiblility that the gauge has become innacurate over all these years, or that if it's been 'repopped' that it's not correct, either.
Posted By: Paul
Re: adjusting the gas tank sender - 07/10/08 07:16 PM
After reading these posts, I would have to agree the replacement pieces are flawed. My road runner's gas gauge was dead on accurate before I restored the car. When I put it back together, I used a new pickup/sender assembly with the untouched original gas gauge. It never goes past 3/4 full and has a lot of fuel left when the needle bottoms out. And all this time I thought it was something I did wrong when I put it back together.
Posted By: Anonymous
Re: adjusting the gas tank sender - 07/10/08 08:27 PM
Quote:
Quote:
i hate to be the bearer of bad news but some of you guys are probably never going to get your sending units to work.
The reason is because many of the reproduction sending units were not built right. Their resistance range from empty to full was not correct. A proper guage should be 10 ohms at full and 73 ohms at empty. you will most likely find yours to a different range. I cant remember what the bad units had for a range but it was something like 0 to 100. that means at 1/4 empty, you will read empty and at full, you'll read 3/4 full
theres no way to fix this as far as i know other than to change out the resistor element to the correct one.
this is a KNOWN problem with reproductions (at least some of them)
I'm not sure I agree with that. If the repop sender has a LARGER resistance change than the old one, it should be possible to add some resistance in parallel with the sender to ground to set the range. Then, it would be a matter of adjusting the thing so that empty is correct on the one end, and adjusting the resistor for full on the other.
Frankly, I'd be happy to have "empty" fairly accurate, but the one thing you do NOT want, is for the tank to be empty before the gauge is!!
Also, don't discount the possiblility that the gauge has become innacurate over all these years, or that if it's been 'repopped' that it's not correct, either.
like I said, I believe if you check it at empty and full, the range on the junky repops are different than the stock ones.
The fact that it only goes to 3/4 full tells me that at empty, it not 10 ohms OR 0 ohms but something greater.
I'll do some math and see if I can work it out.
Posted By: Beep Beep
Re: adjusting the gas tank sender - 07/11/08 08:23 PM
Great info, I was planning on getting a repro, due to my original not being that accurate. When my tank is full it reads between 3/4 and full. I guess I will live with what I have.
Posted By: RapidRobert
Re: adjusting the gas tank sender - 07/11/08 08:30 PM
If I could get it correct on the E end I would be happy with that.
Posted By: roadrunner7070
Re: adjusting the gas tank sender - 07/11/08 09:22 PM
When I sent my dash cluster to Auto Instruments for calibration I sent the new gas tank sender with it and my gauge reads full whenever I fill up and empty when showing empty. That is with a new repo sender.
Posted By: IronWolf
Re: adjusting the gas tank sender - 07/11/08 10:37 PM
Quote:
putting a new tank in, already have a new sender that has been in for a while.
the gauge would never register more than about 3/4 full, when i filled the tank. it measured past empty when i had 4-5 gallons in it.
with the sender out, i found that at the lowest point of travel it went beyond empty, and at the highest point, a little beyond full. so the gauge works fine.
so what i did was mark where the sender was at 3/4 on the gauge, and then move it up to full, and bend the float down closer to that point. but at that point, the float hits the filter, and does not go down all the way. i assume this is fine, as it probably didn't go down all the way to the stop to register empty anyway, witness my 4 or so gallons and the gauge being past empty.
does that sound right? or does anyone have any other suggestions about adjusting this correctly?
I have had success moving the goofy ground strap that clips from the output line past the rubber line. It is flaky. Clean it well , and move it around. Good luck
Posted By: CYACOP
Re: adjusting the gas tank sender - 07/12/08 03:16 AM
Bend the wire float arm to read empty when the tank is empty.
Posted By: W5Duster436
Re: adjusting the gas tank sender - 07/12/08 03:47 AM
Quote:
i hate to be the bearer of bad news but some of you guys are probably never going to get your sending units to work.
The reason is because many of the reproduction sending units were not built right. Their resistance range from empty to full was not correct. A proper guage should be 10 ohms at full and 73 ohms at empty. you will most likely find yours to a different range. I cant remember what the bad units had for a range but it was something like 0 to 100. that means at 1/4 empty, you will read empty and at full, you'll read 3/4 full
theres no way to fix this as far as i know other than to change out the resistor element to the correct one.
this is a KNOWN problem with reproductions (at least some of them)
I just bought a 3/8 unit from Mancini a few weeks ago and am having the same troubles. First I didn't check it for binding before putting it in as my gauge would only go to E. So I took it out and checked it and bent it a slight bit just to keep it from hitting the pickup tube. Put it back in and still after putting 5 gallons in it barely reads above E. I ohm'd it out before putting it in but didn't check it against the original (rusty, rusty) unit. I just wanted to verify the full range worked and it did. Can't remember what the readings were but obviously not right. Even as rusty as my original unit is (sat since 1979) it reads 9 ohms full and 63 ohms empty. So I guess that's what my gauge is calibrated for.
Gonna pull this new one back out once again and check it. If I can't get it to work then it's off to the beadblaster to get the original cleaned up and have a 3/8 line put in place of the 5/16. Probably would be okay with the 5/16 though as I won't be over 500hp.
Posted By: mickm
Re: adjusting the gas tank sender - 07/12/08 06:24 AM
i bent the wire holding the float. since i didn't have any specs on what the ohms should be, i just went with that. this is wildly inaccurate, but with the pickup tube and filter sitting flat on the bench, the top of the float was 7" off of the bench. i bent it down to 6 5/8". it looked like it needed more, but even that and the float barely hits the stop.
i will see what this does and let you all know. seems to me that this should be able to be taken care of by bending the float, and not messing with resistors.
i'm hoping to get the car running tomorrow, so will post again.
Posted By: mickm
Re: adjusting the gas tank sender - 07/14/08 10:32 PM
well, this is a bummer. after bending the float DOWN, which logic tells me should place the sending mechanism higher in position for the same amount in the tank, thereby having the gauge read higher for the same amount of gas, it appears to actually be reading a little lower.
i put 9 gallons in, which should be 1/2 gallon short of half a tank, and it barely reads 1/4.
doesn't make sense to me. i will pull it at some point and try bending it some more. i really don't want to go with a bunch of resistors in the line...
oh well, at least i have a tank that isn't leaking gas at $4.60/gallon!
Posted By: W5Duster436
Re: adjusting the gas tank sender - 07/14/08 11:04 PM
Quote:
well, this is a bummer. after bending the float DOWN, which logic tells me should place the sending mechanism higher in position for the same amount in the tank, thereby having the gauge read higher for the same amount of gas, it appears to actually be reading a little lower.
i put 9 gallons in, which should be 1/2 gallon short of half a tank, and it barely reads 1/4.
doesn't make sense to me. i will pull it at some point and try bending it some more. i really don't want to go with a bunch of resistors in the line...
oh well, at least i have a tank that isn't leaking gas at $4.60/gallon!
Sounds like adding resistors is the only choice. I am going to take my original sender and have it bead blasted and replace the 5/16 line with a 3/8 line. Sending this one back.
Posted By: Anonymous
Re: adjusting the gas tank sender - 07/15/08 12:15 PM
Quote:
i hate to be the bearer of bad news but some of you guys are probably never going to get your sending units to work.
The reason is because many of the reproduction sending units were not built right. Their resistance range from empty to full was not correct. A proper guage should be 10 ohms at full and 73 ohms at empty. you will most likely find yours to a different range. I cant remember what the bad units had for a range but it was something like 0 to 100. that means at 1/4 empty, you will read empty and at full, you'll read 3/4 full
theres no way to fix this as far as i know other than to change out the resistor element to the correct one.
this is a KNOWN problem with reproductions (at least some of them)
