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Premium Member
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Discussion Starter #1
I'm replacing the gas tank and sender in my XR7. I'm using a standard
sender instead of the XR7 unit. My XR7 has one green and one yellow wire
going to the sender. Which of these two do I hook up to the standard
sender?

Much appreciated...
 

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1,832 Posts
Logan I went out to the garage to check my non xr7 for you. I dont know if my rear harness is right because it also has a 2 wire harness running to the tank. I undid the masking tape (thats right masking tape)that held the splice to the wire going to the sending unit and it was hooked to the yellow wire. And I know mine works. So I would say you need to hook to the yellow to the sender. Dont ask me about the masking tape or I might go off on how I just found the surface rust starting on my front floor boards because the dumb sob put new carpet and underlayment in without putting any cowl or floorboard body plugs back in. Belive it or not this car was done by a regionial director of the ccoa. I wont give his name except he is from Manitowoc WI. Sorry I went off like that. I hoped I answered you question.
 

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Discussion Starter #3
Thanks Mark...

Hey, by the way, why was there masking tape on your sender wiring? That's strange eh...

mooohahahhahaha...

:D

Don't feel bad, I just removed my carpets and underlay to find it...MOIST... EeeeewWweEEWeWWWewew!! Out came the rebreather and some thick rubber gloves...

YUCK
 

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Discussion Starter #4
Woohooo!

I finished... My cat now has a new tank, sender, WORKING GAS GAUGE, and new stainless steel lines from back to front...

I was almost giddy filling it up with $1.90 a gallon gas, just to see the gas gauge actually work properly... :D
 

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Two wire sending units

Don't quote me, but I think that second wire is for the low fuel warning light found on XR-7s.

Last year I just went nuts with my wife's 70 Mach 1 (21k original miles). Her fuel gauge quit working and I tried to trace the problem. The gauge worked when I put voltage across it (after spending hours taking the dash apart!) , the wire had continuity, so i deduced that the sender died. WRONG! It turns out that the ground was faulty.

What ground, you ask? The lock ring that holds the sending unit plate to the gas tank acts as a conductor between the sending unit and the gas tank (and therefore the chassis ground) since the rubber o-ring seal is an insulator. Well, that sending unit lock ring had just enough rust on it to break the circut and cause the gauge to quit working.

How do I know? I checked the new sending unit before I put it in just to make sure everything was going to be OK once I replaced the sender, and just for the hell of it I checked the old sending unit after taking it out. The old sending unit worked just fine. Oh well, better safe than sorry, so I left the new one in there. All that work for a 98 cent part (the lock ring, not the sender!)!

No wonder I keep my hair cut short.... It is so I can't grab it and tear it out in frustration when dealing with these cars! ;)
 

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Logan, I told you not to mention the masking tape. I had just cooled off from this morning. Just for that I will tell you that I paid 1.65 to fill up this morning. (such a deal huh?) I take it the yellow wire worked. I liked cougarcj tip on the ground, as I may have to check mine out. Mine will only go to 3/4 when I fill up but it shows empty about the right time.
 

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Discussion Starter #7
Ack!!

The gauge was working properly a few days ago. Now, the needle on the gauge just swings all the way right past full. Nothing has changed, anyone got any ideas what's up?
 

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Yes Yellow wire is the feed and the green is for low fuel in XR7s.The grd prob has been properly addressed and isn't masking tape for painting?The only other prob that surfaces is the float can sink giving an inaccurate reading.Pretty much can give up on the low fuel working.I understand they never worked properly from day one.Its a little ball in a cage that floats in the gas and when the gas drops so does the ball connecting ground to the low fuel relay lighting the light in dash. At least thats the theory
 

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Discussion Starter #12
Yeah, I didn't even bother with the low fuel and just went with a standard sender. I'm just happy it's working, so I can move on to the 10000 other things that need to be replaced or put back together...
 
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