new fuel sending unit ugh!

[70bigblockdodge]

There is a ohm reading for full and empty to " pre calibrate" the new sending unit by bending the arm to read desired ohms when at float up full and float down empty.

 

[MrMoparCHP]

Meter Match will not compensate for a bent arm, if the arm is bent and not touching the bottom of the tank Meter Match cannot fix that, or it is bent too much and showing a level when you are empty.

Fix the arm first!


Alan

 

[Zaggart]

First, describe what was going on before you had the sender changed.

As I see it, there can be several things wrong.... First suspect is the new sender.

A lot of folks are now going to talk about grounding the sender and while that is important, since your gauge seems to be reading high, that would tell me there's not a ground problem. Also, since it's reading high, I suspect the wiring is good.

Next possible culprit is the voltage limiter located behind the dash. This gives 5 volts to the gauges to make them work correctly. I always suggest replacing these with a new electronic version.

Then there's the gauge. Usually not the problem, but it could be.

Ultimately, to get a correct reading gauge, you can install a Meter Match which will compensate for errors in the gauge/sender. Here's my experiences: Gas Gauge Fix

Should this Meter Match be easy enough for a qualified mechanic to install and calibrate? I'm in the same boat with a max 3/4 gauge that we've determined to be the sending unit. I'd rather not go through 3-4 of them to find a good one.

 

[saforwardlook]

I have recently bought 3 new fuel tanks and sending units, etc. from Vans and every one of them reads accurately. I did get on them a year or two ago about why they couldn't get the sending units calibrated correctly and it appears they have solved that problem. Very accurate at least now.

I tend to interact with suppliers until they get things right - just waiting around for someone else to get on them or hope against hope that the vendors will solve their own problems doesn't get the job done.

I would not use a older used part that has been around the block without testing it first for the proper resistance over the full range and that the arm matches the contour of the previous one (assuming it worked accurately) before installing one as a guideline.

 

[Ross Wooldridge]

sorry guys...must have needed snickers last night...as a shop owner/ mechanic for over 45 years i lose my cool when i hear anyone automatically blame the mechanic...and believe me there are PLENTY of incompetent and dishonest mechanics out there...and there are PLENTY of bad aftermarket replacement products too...and i certainly had no idea the OP couldnt work on his own car...maybe leading with that would have prevented me from putting my foot in my mouth....considering most of the suggestions given were also things he couldn't do himself i doubt anyone else was aware of the situation...so once again sorry...but for future reference, if you walk into a shop with your own part and say ''install this" that's all you are going to get...and when it doesnt work they'll probably blame the part....IF they are a competent shop and you ask them to troubleshoot and fix the problem they will...at a much greater cost....the majority of us are on here because we cant find anyone out there that has a clue that we can afford to pay, that's why we do this stuff ourselves....i cant even imagine owning a vintage car and having to rely on someone else to fix it....unless i was Jay Leno...ps cant ask my parents if they're proud because they're dead but thanks for asking

All good - thanks for stepping up to the plate on this. Yes - all of us - me included at the top of the list - can have our moments of these sorts, but it takes a real man to own it.

 

[Big_John]

Should this Meter Match be easy enough for a qualified mechanic to install and calibrate? I'm in the same boat with a max 3/4 gauge that we've determined to be the sending unit. I'd rather not go through 3-4 of them to find a good one.

Gas Gauge Fix

That's my install.

Can a "qualified" mechanic install? Geez, I don't know... "Qualified" is a broad term.

It's an easy install though.

 

[Big_John]

Meter Match will not compensate for a bent arm, if the arm is bent and not touching the bottom of the tank Meter Match cannot fix that, or it is bent too much and showing a level when you are empty.

Fix the arm first!


Alan

The float/arm does need to function correctly in that the float goes all the way to the bottom when empty and all the way to the top when full.

Other than that, the Meter Match will correct for total resistance, or what most people would call "zero" and then correct for the span at "full". It also can correct for linear inaccuracy. For example, most of the gauge/senders are never accurate at half or quarter full. The Meter Match can correct for that with a little patience and tuning.

But yea, it doesn't make "broken" work.

 

[1970FuryConv]

@straightjob I don't know how you do any mechanical work from a wheelchair. Kudos to you for getting in there and trying. Lots of other people would be completely shut down and give up. You definitely are not a quitter. Well done!

I'll think of you next time I complain about arthritis slowing me down. Ben

 

[pomonamissel]

you must calibrate them together . maybe even some electrical mods to put them in sink oms wise .

 

[C Sickness]

Depends on a couple things.

If that's for the '70 300 in your pic, there's 2 possibilities. If you don't have a low fuel warning light, it's on the back of the dash cluster. Hard part is getting to it.

If you have the warning light, it's part of the low fuel relay near the right side ash tray. With the low fuel relay, the voltage limiter isn't going to be a "plug and play" and the aftermarket limiter won't work with it.

I had the warning light and wanted to keep it, so I incorporated a Meter Match with their optional low fuel warning light, a relay (to light the light) and a cheap voltage limiter to make the drop to 5 volts, but as said, it's not "plug and play". I believe you should be able to remove the low fuel relay and use the dash "plug in", but you'll lose the low fuel warning.

I've never seen a low fuel light. I guess I have to drop the column, and tear into the dash? Is a low fuel light an option that might be shown on the fender tag?

 

[straightjob]

All good - thanks for stepping up to the plate on this. Yes - all of us - me included at the top of the list - can have our moments of these sorts, but it takes a real man to own it.

Thanks for explaining been a rough year another surgery Friday ugh! The frustrating thing is he asked me to source the part , which i did and Vans doesn't have any: any other suggestions where to source ? I wasn't blaming the mechanic , he's a good guy (GM !) but with the funkiness' of Chrysler electrical systems thought there was something we were missing. I've had a few imperials and joined their club and much like you gentlemen they had great solutions to my forays into the Mopar electrical world! Thanks again. ill try to find another whiles hes busy with my 300 L !

 

[Big_John]

I've never seen a low fuel light. I guess I have to drop the column, and tear into the dash? Is a low fuel light an option that might be shown on the fender tag?

Look under the dash to the left of the steering column. If there's a limiter there, you don't have the "low fuel" light.

 

[live4theking]

I have recently bought 3 new fuel tanks and sending units, etc. from Vans and every one of them reads accurately. I did get on them a year or two ago about why they couldn't get the sending units calibrated correctly and it appears they have solved that problem. Very accurate at least now.

I tend to interact with suppliers until they get things right - just waiting around for someone else to get on them or hope against hope that the vendors will solve their own problems doesn't get the job done.

I would not use a older used part that has been around the block without testing it first for the proper resistance over the full range and that the arm matches the contour of the previous one (assuming it worked accurately) before installing one as a guideline.

Just curious if they gave you any idea what the cause of the inaccuracy was. I ask because I got my unit from them almost 7 years ago. It only reads between 5/8 - 3/4 tank when plumb full. I'm thinking of pulling and tweaking the float arm a little bit this weekend to see if the accuracy will increase any.

 

[Toolmanmike]

Original sender coil vs the aftermarket coil. If your gas tank was a perfect cube shape, the aftermarket sender would be fairly accurate. The Meter Match is probably your best bet.

 

[saforwardlook]

Just curious if they gave you any idea what the cause of the inaccuracy was. I ask because I got my unit from them almost 7 years ago. It only reads between 5/8 - 3/4 tank when plumb full. I'm thinking of pulling and tweaking the float arm a little bit this weekend to see if the accuracy will increase any.

They gave me no explanation as to what they changed. All I know now is that the several recent tanks/senders are reading correctly. I really doubt that changing the float arm will fix anything but rather just make the constrained range reading occur in another segment to the fuel gauge needle travel. In my opinion the resistance reading of the past senders just did not cover the original range of resistance that Chrysler specified.

 

[HWYCRZR]

Meter match is easy.
Also there is a setting in the Metermatch that will also act as a regulator if you are only powering one gauge. However in my case the '68 Dodges run 12 volts to the fuel gauge, convert it to 5 volts with a regulator built into the fuel gauge and then power the temp gauge. If you have a temp light instead of a gauge you may be able to simplify.

In my '68 Dodge I needed to remove the gauge and disable the old built in regulator. If the '68 Chryslers had the outer regulator it will be easier.

I blew out my solidstate dash regulator and meter match last week when I was having starter problems and spiked my system by removing the ground after a cold start. The engine wasn't running fast enough to have the alternator keep the car running. When I quickly connected the negative cable before the engine quit turning it immediately started and gave enough of a spike to do damage. ( I have another thread out there telling my road trip story)

Anyway I will be re-installing both this weekend. The meter match is awesome and gets rid of second guessing your fuel situation.
I use full fuel to calibrate the top end, and used my gauge tester to set the low end. If I really wanted to get accurate, I would siphon out the remaining fuel, fill back 2-3 gallons, set my low end, then go to the gas station, fill up and set the high end. ( If I wanted to go really crazy I could set mid range as well. I think the instructions are available on Technoversions.com website (Meter Match)

I will take some picture as I am doing it.