Fuel gauge wont work
 

My 12a has a 13b turbo fuel tank in it, since it was installed the fuel gauge wont work. Have tried a few things but none seem to work... Has anyone had this problem or could think of a way to fix it?


It actually works till about 1/4 of a tank and then u dont know how much u have until u run out lol...


Thanx for any help guys... :bigthumb:

I am having the exact same problem on my '83 Rx-7. I works fine until its 3/8 of a tank and then goes all the way to empty.

The FSM shows a factory tool to test the gauge/sending unit, but has anybody any ideas how to do the testing without swapping out parts?

I am guessing its the tank sending unit.


John

clean the fuel tank sending unit's connector
they get dirty easy and fuck up the reading

Yea tried that did not make a difference.


John

guess you sending unit is just borked then???

I had an issue with my fuel guage in my 1983 RX-7, and it took me several class days to hunt it down. It ended up that I was not getting any signal to the fuel gauge. I would get at maximum three-quarters full, and then it simply stopped reading.

That problem was the fact the contacts on the fuel sending unit were very dirty, and the contact on the back of the instrument cluster was dirty. The specs for the fuel sending unit (according to Haynes / Mitchell) should be ~3 ohms at full, and ~110 ohms at empty.

Since you've changed your gas tank, did you replace the sending unit as well? It may not use the same method of sending fuel level as the straight resistance method. In my '83, the fuel gauge is a bimetallic strip that uses the voltage drop it gets (which is less as the resistance of the sending unit goes up) to heat the strip with a small heating coil, which makes it go up.

I can't be of much more help then throwing random information at you. My advice would be to pull your instrument cluster, and check the overall condition of the circut board on the back, and the resistance from the X-5 connector Y wire (which goes to the sending unit then to ground in my vehicle) to a ground on the dash and read that, make sure nothing is out of spec, or you're getting a wierd reading. Do it once when your gauge is reading, and once when its being pesky to see what the difference could be.

On a different note... is the issue more of the fact that it goes to E after hitting a quarter of a tank or that it 'sticks' there until you hit empty? There's also a little easily bent bit of metal that acts as a stop on the instrument cluster. If you pull it, check the stop, and make sure all your connections are good on the circut board to start.

Looking at the Mitchell information for a Third Gen cluster and fuel sending unit, I found the following information about the special testing tool:

"With special tool set to 7.4 ohm resistance, fuel gauge should indicate full; with resistance at 31.5 ohms, gauge should indicate half full and with resistance at 75.9 ohms, gauge should indicate empty."

This is with the special tool essentially acting as the sending unit for additional resistance in the circut. It almost matches up with the specs for the '83 model I have, for overall (being at smallest around 4-7 ohms and at greatest 95-103 ohms) but wouldn't go all the way down at empty. Could this be the problem?

Check the resistance in your sending unit for the TII tank, make sure its in spec with the resistance needed by your fuel gauge.