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Discussion Starter · #1 ·
Question about fuel gauge on 84 Supra. When the car was new, and I filled the tank, the fuel gauge needle went all the way up, past the top line (F). In the past few years, the highest point the needle ever reaches is about halfway between the 3/4 and F marks. Has anyone else ever seen this problem? Is there an easy fix, or is this a problem inside the tank sensor?

Also, the fuel level seems to drop very fast on the gauge, but at 1/8 on the gauge, I can only add 9 gallons (or so) at the pump ... suspecting early shutoff, I've forced it in the past, but it really does overflow after about 9 gallons. I know when the car was new I could run it down to about 15.5 gallons (when the tank read empty), which makes sense for a 16.5 gallon tank.

Fred B.
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1984 Super Red Supra
 

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I'm having the same problem. It started after I had the car parked for 4 days for a head swap. I pulled the sender out and everything looked really good, I put it back in and it read correctly when I went and filled it up but now it does the same thing again. I dont see how you ever got 15.5 gallons in there since its a 16.1 gallon tank I have heard of people running out with 2 gallons still in the tank because the fuel pump couldnt pick it up. I dont think its early shutoff is just that the guage is still wrong so 1/8 is closer to 1/4 or 2/3 if the guage were working properly.
 

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Yes this is a common problem with the Celica's and the Supra's. I believe the gas tank float for the gauge. Is made of a phenolic material. It's gets fuel saturated and then it weights more. Same thing use to happen to the floats in the old carburators. To fix it is not that hard. You can find the acess cover in the rear hatch. Remove the cover. Then remove the gauge sending unit. You will see that it has a metal rod attached to the float. Bend the metal rod up some till you see the gauge reads full again. Button it all back up and your done.
 

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Take the metal cover off the top and clean the potentiometer scale off with a scuff pad. They get all corroded after 15+ years in a gas tank. This has fixed it for me on past Supras.
 

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Bend up??? :scratch:
Don't you mean bend down.
 

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Mine did this when I first got it and it bothered me so I put a brand new factory sending unit in and it still did it. I just gave up. :mad:
 

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Discussion Starter · #8 ·
Dave A. said:
Hmmmm....okay, so where is my real long reply to a post on how to fix this problem? :roll:
Okay, we're still waiting for your real long reply. Or is this some kind of inside joke I'm not aware of yet? :?:
 

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Well I told you how a lot of people I know have fixed theirs. And yes you bend the rod down some not up. Like 82MKIILtype said in his post.
 

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Discussion Starter · #10 ·
Oh, I thought somebody else had yet another method.

I'll give the rod bending a try this weekend, but it sounds like replacing the bulb float with one made from different material might be a better solution?
 

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Check the MKII Yahoo group archives for my long reply. Bending the float arm is an easier fix. If that doesn't work then try readjusting the stainless steel slider on the potentiometer inside the sending unit.
 

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Open hatch,

Lift up bottom cover for spare tire.

Look to your right, you will see a round metal plate. Remove it, you'll then have access to the sending unit.
 

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okay... I got the float out, and no matter where I bend it, the most it will get full is 1/4 tank... there is also this funny little wheel looking thing connected to it, whats that?
 

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Discussion Starter · #16 ·
Just reporting back (finally) - I bent the rod down (not up) a little, and this helped. The gauge was reading almost full when I knew it was full. But recently (i.e. yesterday) it was reading all the way full, despite the absence of further modifications. I'm thinking this might have had something to do with a fuel system cleaner additive I put in a week ago or so?
 

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I'm going to attempt this little trick on my aunts car ( toygrl83 ) tomorrow, something is seriously up with her guage!
She drove 200 plus miles and the guage still read 1/2 tank, they almost ran out of gas because of it. I never had this problem on any of my mk2s, but both her and my brother in laws mk2s are 83 Ptypes and have this problem. Are their any difference in model years fuel sending units and their floats?
 

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TanyasMk2Blackpra said:
Are their any difference in model years fuel sending units and their floats?
I believe the sending units are the same for 82-86 MKII's. Bending the float arm down may work as long as the arm doesn't already come up against it's stop with a full tank of gas. Otherwise, bending the arm down isn't going to be the fix since the arm won't actually raise any higher with a full tank. The little wheel on the bottom of the sender is a vibration damper that helps keep the sending unit parts locked in place inside the gas tank and free from movement from vibration.

If bending the float arm down doesn't work, here's the numbered procedure that will or should work.

1. Remove the sending unit from the gas tank

2. Remove the metal shroud from around the potentiometer at the top of the sending unit by bending the small tabs up with a small screwdriver and needle nose pliers.

3. Raise the float arm up against it's stop and visually inspect the position of the stainless steel wiper that contacts the potentiometer windings.

4. The left (straight edge) of the stainless wiper should be exactly parallel with the side of the potentiometer housing. (Note that usually you will find that the wiper has moved just a tad to the right from parallel).

5. Using a small adjustable crescent wrench, turn the square shaped brass nut attached to the stainless wiper to the left to reposition the wiper to it's original position (back to exact parallel with the side of the metal housing).

6. Use some spray carb cleaner to clean the potentiometer winding (not steel wool or any other abrasive material(s).

7. Reassemble the housing cover to the sending unit and bend the metal tabs back down to their original position.

8. Install the sending unit making sure that the gasket is in good shape and intact. (replace the gasket if you're in doubt of it's condition to prevent any gasoline leaks from the gas tank! very important!!)

9. Reconnect the wiring connector on the sending unit.

There you have it...all in a nutshell!

:lol:
 

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well we pulled the fuel sending unit out, good lord it is nasty, all rusted!
we plugged it in while it was out of the tank and I watched the needle slowly drop...then we put it back in the tank and it wouldn't go over 1/2 tank while you could visibly see the tank is full. we just decided on getting a new unit eventually, fixing or trying to fix the current one would be like beating a dead horse
 
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