Question about the infamous fuel level sender

[MikesFixedRoof]

So yesterday I decided to remove and inspect the fuel sender unit in my '90 turbo because the low fuel light had stopped coming on a while back, yet the gauge always seemed to work fine and stay rather accurate. So I removed the unit, and the protective cover over the coil winding and contact arm. Other than looking a bit gunked up, I saw nothing wrong with it. I cleaned it up with some emery cloth and a bit of electrical contact cleaner. The arm stays in contact with the winding from top to bottom, and the resistance I measured with the arm at the lowest point was right on spec. The car has about a 1/4 tank of gas in it now, so I'll just have to wait a day or so to see if the light will come on. If it doesn't, what could it be? What part of the sender unit actually trips the light? :1zhelp:

 

[GrimJack]

Did you check the light in your dash first?

 

[Dirgle]

Like Grim said, in situations like these it is usually the bulb. But to answer your question, the low fuel warning light is not controlled by the fuel level sender( the one with the float on a pivoting arm). Instead it is controlled by a sensor located at the end of the fixed arm.

 

[jetjock]

Did you check the light in your dash first?

Now that's entertainment

 

[supraguy@aol]

Why is it infamous? Ive never had any issue with my sender or my low level sensor.

 

[GrimJack]

The sender has always had problems. The question - why doesn't my fuel gauge work properly from 1/4 to 3/4 of a tank? - has been asked, and answered hundreds of times, since long before SF / SM. I remember it coming up on the old SOGI mailing list, and I'm sure the fix is still listed as a tech tip on Supras.com as well.

Luckily, it's an easy fix.

 

[Backlash2032]

Lol mine works.. just the last "quarter tank" is about half of the tank hahaha. Is that the issue?

Sent from my HTC Droid DNA

 

[MikesFixedRoof]

Did you check the light in your dash first?

Nope. Between all the problems I've heard people have had with the sender, and the fact that it was alot easier to pull it out than the instrument cluster, I figured I'd rather start from the sender end.

 

[MikesFixedRoof]

Like Grim said, in situations like these it is usually the bulb. But to answer your question, the low fuel warning light is not controlled by the fuel level sender( the one with the float on a pivoting arm). Instead it is controlled by a sensor located at the end of the fixed arm.

Ah ha. I was wondering what that little cylindrical thing on the fixed arm with the copper wire was! So that sensor doesn't really go bad huh? Damn. I guess now it's a matter of how badly I really want the light to work again.

 

[MikesFixedRoof]

The sender has always had problems. The question - why doesn't my fuel gauge work properly from 1/4 to 3/4 of a tank? - has been asked, and answered hundreds of times, since long before SF / SM. I remember it coming up on the old SOGI mailing list, and I'm sure the fix is still listed as a tech tip on Supras.com as well.

Luckily, it's an easy fix.

I was actually a bit surprised at how many people I found with actual problems with the sender/gauge when I was researching my issue and really found nobody with the same problem. The Digidash cars seem to be worse.

 

[MikesFixedRoof]

So I pulled the instrument panel today, and found this bulb & socket on the back of the panel directly behind where the gas gauge is. Is this it? or do you have to peel the panel apart to get to it?

 

[jetjock]

When you began all this why didn't you simply ground the proper connector pin in the hatch like the TSRM says?

 

[MikesFixedRoof]

When you began all this why didn't you simply ground the proper connector pin in the hatch like the TSRM says?

Didn't find the testing procedure in the TSRM until after the fact. Oh well. Either way I've come to the conclusion that it is in fact the sensor on the sending unit that is faulty.