Fuel tank translator

[BruceK]

When I refurbished my Mini's fuel tank, I decided it was the perfect time to install a new sender unit, as the old one was nearly 40 years old. It was one of those "might as well" things.

It turns out the new sender unit is not any better friends with my Mini's fuel gauge than the old one was. They both sort of worked, but neither one really showed Full or Empty correctly and I basically ignored them and just filled up the tank about every other time I drove the car to ensure it always had fuel.

But with a refurbished fuel tank and a new sender unit, I wanted to fix the problem. So I decided to install an item called MeterMatch which is designed to make your fuel gauge completely accurate. Basically, it's a little computer that goes in line in the wiring from the sender to the fuel gauge. It receives whatever the sender unit is sending, and then translates that information into what the fuel gauge is expecting to receive to display correctly. I think this product is normally designed to be positioned hidden in the dash somewhere close to the fuel gauge. But I decided to install mine in the boot closer to the sender unit. (more room to work there).

I have not yet completed the installation. I drained the fuel tank to get the correct calibration for Empty on the gauge. Tomorrow, I plan to fill up the tank and calibrate the Full setting. The MeterMatch unit is designed interpolate readings between the two extremes to display 3/4, 1/2 and 1/4 on the gauge. So we'll see how that works. There are also ways to fine tune the unit to be more accurate for the readings between an empty tank and a full tank - apparently this is very useful if you have an odd shaped fuel tank that doesn't empty in a linear fashion.

So we'll see how that goes. I was reading the instructions and also learned that this unit can be used for a temperature gauge in much the same manner as a fuel gauge. Interesting.

(The circuit board sits in a little black plastic case, but it comes out of that during the calibration process).

[94touring]

I've always bent the float arm to register 0 accurately but gave no mind to full.  I'm curious what variables in ohms that board gives you for the different settings.

[MiniDave]

Yes, I used one of those to fix Deighton's temp gauge on his 73 Mini, I could never get it to read right no matter which sender I used so I used one of those to set the "fully warmed up and driving down the road" to read dead center of the gauge.

This reminds me of something Bruce said many years ago when talking about oil pressure gauges, if you don't have the gauge, you don't worry about it!   

My fuel gauge is right twice - full and empty - anything else is a pure guess. It comes off full in about 20 miles and drops to the middle of the gauge pretty quickly, then it stays there for a loooonnnnngggggg time. When it gets down to the red mark which I suppose is the reserve mark, I can only add 5 gallons to the 9 gallon tank. Oh, and that's with a new sender.....the old one had breaks in the winding and would drop to zero at about half tank - pretty disconcerting the first time it happened! one advantage of Mini tanks is that you can peek in with a flashlight and see exactly how much is in there.

The gauge in Don's pup is equally funky, but when it says half, you need to get gas soon, as you're down to less than 2 gallons out of a 7 gallon tank. He's put 6.5 in it more than once thinking he still had plenty or when it was miles to the next stop!

BTW Bruce, how did the tank turn out, do you think you've cured the seeping and smell?

[MPlayle]

I guess I am pretty lucky with my Van's fuel sender and gauge.  They are reasonably accurate.  At half on the gauge, it takes about 3.5 gallons and at 1/4 on the gauge, it takes about 5 gallons.  Those tend to be the readings when I fill it on meeting Bruce for the various Cars&Coffee events we go to.

[BruceK]

I've always bent the float arm to register 0 accurately but gave no mind to full.  I'm curious what variables in ohms that board gives you for the different settings.

Here are the specs.

[BruceK]

Yes, I used one of those to fix Deighton's temp gauge on his 73 Mini, I could never get it to read right no matter which sender I used so I used one of those to set the "fully warmed up and driving down the road" to read dead center of the gauge.

Man I wish I knew about that capability 4 years ago with the flakey temp gauge on the Toyota truck I imported from Japan. It would have been so much easier than me fitting a secondary temperature gauge with a capillary feed.

This reminds me of something Bruce said many years ago when talking about oil pressure gauges, if you don't have the gauge, you don't worry about it! 

I think that was Mazda's philosophy with the first generation Miata. Halfway through its production run, they took away the capability of the oil pressure gauge and just made it basically an analog idiot light. If the needle was in the middle of the gauge, you had oil pressure. But the needle never moved with engine revs.

BTW Bruce, how did the tank turn out, do you think you've cured the seeping and smell?

Yes, the gas smell in the boot is completely gone.

[BruceK]

So I fulled up the Mini's tank today to calibrate the Full setting on the MeterMatch.

I'll update here as I drive and I start drawing down the fuel in the tank. And hopefully the gauge will read correctly. But based on the fact that I'm only really just driving to car shows it's gonna take a while. 

[94touring]

A lot of radio shacks around there?   

[MPlayle]

A lot of radio shacks around there?   

There used to be about 14 or so in the area.  All are gone.

[BruceK]

A lot of radio shacks around there?   

When I lived in DFW we had Fry's which was like a Radio Shack times 100. Outta business now.

[MiniDave]

Boy it seems to me that the one I used just had a little potentiometer, you just turned the knob till you got the reading you were after.....

[94touring]

Boy it seems to me that the one I used just had a little potentiometer, you just turned the knob till you got the reading you were after.....

Boy it seems to me that the one I used just had a little potentiometer, you just turned the knob till you got the reading you were after.....

I was wondering if an adjustable regulator like that would do the same thing.