Fuel tank sizes?

[RETed]

Originally Posted by Rotary Evolution

a common issue on the 2nd generation sending units is for the sending unit wires to fray near the bottom of the tank, throwing off their calibration at lower fuel levels.

i've been noticing it alot more lately as the cars are getting older.

I have no idea what you are talking about...

If it was indeed fraying, there would still be electrical contact.
When the wire completely broke, it would obviously lose signal.
Even if you had one wire still intact, the voltage is low enough that one strand of wire would still provide an adequate signal.

I just changed my fuel level sender in my 1987 turbo and saw no evidence of "frayed" wiring.
It was the potentiometer resistance sweep (common problem for any type of (non-sealed?) potentiometer) to degrade this way.


-ted

[chibikougan]

Do remember they idiot proofed gas tanks. They have a "Reserve" so that people running them to Empty did not run out of gas right at that moment. I know my Taco has a reserve to get another 100+ miles to get some gas.

On my 74 BMW 2002 Empty was Empty I am not sure as to what year they enacted this.

[TitaniumTT]

Originally Posted by chibikougan

Do remember they idiot proofed gas tanks. They have a "Reserve" so that people running them to Empty did not run out of gas right at that moment. I know my Taco has a reserve to get another 100+ miles to get some gas.

On my 74 BMW 2002 Empty was Empty I am not sure as to what year they enacted this.

I've noticed that with alot of newer cars as well, take my Jeep. When the light goes on there's about 100 miles left if you're on the highway at a reasonable speed. Cold winter mornings letting the truck warm up and siting in traffic, 50 miles. I know this becuase I put 5 gal in my mounted jerry and drove the thing empty, twice Then I drove a few miles to the gas station and put 15.3 gal into a 22 gallon tank. Stupid vapor reserve things

[RICE RACING]

Real cars come factory standard with 120lt carbon fiber fuel tank

[TitaniumTT]

Originally Posted by RETed

I have no idea what you are talking about...

If it was indeed fraying, there would still be electrical contact.
When the wire completely broke, it would obviously lose signal.
Even if you had one wire still intact, the voltage is low enough that one strand of wire would still provide an adequate signal.

I just changed my fuel level sender in my 1987 turbo and saw no evidence of "frayed" wiring.
It was the potentiometer resistance sweep (common problem for any type of (non-sealed?) potentiometer) to degrade this way.


-ted

I had the exact same problem on my sender when I was using the stock dash.

When I changed out the dash and built my own using all aftermkt gauges I first tried the autometer generic replacement sender = SHIT
Then I tried the marine Tempo sender = less shit, but still shit.
Then I bought a new Mazda sender and a programable autometer gauge = awesome.
Then I built my own tank and went with a WEMA and the same Autometer programable sender = awesomeness

If you need to replace the sender, which I suspect is highly likely, as Ted said, non sealed units as they are, you can actually see corrosion on the sweep giving inaccurate signals, I have yet to find a better sender than the Mazda units. Aftermkt wise, WEMA is the way to go.

[Rotary Evolution]

Originally Posted by RETed

I have no idea what you are talking about...

If it was indeed fraying, there would still be electrical contact.
When the wire completely broke, it would obviously lose signal.
Even if you had one wire still intact, the voltage is low enough that one strand of wire would still provide an adequate signal.

I just changed my fuel level sender in my 1987 turbo and saw no evidence of "frayed" wiring.
It was the potentiometer resistance sweep (common problem for any type of (non-sealed?) potentiometer) to degrade this way.


-ted

take a pill...

when the wires are worn the resistance gets thrown off giving a less accurate signal at the lower fuel level range where the most wear generally is. eventually the wires break and the gauge reads zero before the tank is actually empty, i figured you could gather what i was getting at. i have seen a number of 2nd gens with frayed wires below 1/4 tank which worked fine up until that point then dropped to 0 on the gauge as soon as they hit the bad spot.