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68 4 door chevy impala fuel sending unit


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sublimeaces
User

Sep 30, 2012, 5:07 PM

Post #1 of 11 (1649 views)
68 4 door chevy impala fuel sending unit Sign In

My sending unit is acting funny, and before i go out and buy a new one i wanted to pass this by you guys.

The car has been sitting for a while i recently got into auto class and have been working on it ever since.

In my many miles of driving it, over 3000 i noticed the fuel gauge randomly goes up and down which makes me think the float is just old and needs cleaning in the tank. It does stick for a long time but will randomly move anywhere from full to empty.

what do you guys think?


Discretesignals
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Sep 30, 2012, 6:05 PM

Post #2 of 11 (1628 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

Didn't the auto instructor teach you guys/gals how to test sending units?





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sublimeaces
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Sep 30, 2012, 6:26 PM

Post #3 of 11 (1623 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

im not there yet, im not even half way through my first semester. classes consist of brakes, front suspension/aligning, hydrolics, and welding.

sorry kinda mislead, got the car 3 years ago been working on it then decided to get into automotives as a career. to be honest probobly have done more in the short time in school on the car then those 3 years hah


(This post was edited by sublimeaces on Sep 30, 2012, 6:29 PM)


Discretesignals
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Sep 30, 2012, 7:14 PM

Post #4 of 11 (1615 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

You should ask your instructor that does electronics to show you how to test a sending unit and its circuit. They should be able to show you easily how to diagnose your problem. It could be a sender problem, but it could also be a poor connection in the circuit or possible gauge cluster problem too. They can show you how to test that circuit a lot better than we could over the internet. Best time to ask them would be when they are going over fundamentals of electronics and electrical circuit diagnosis and repair.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Sep 30, 2012, 7:15 PM)


sublimeaces
User

Sep 30, 2012, 7:26 PM

Post #5 of 11 (1606 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

awsome will do, next time its up on the lift im going to look for wires and see if its visible without dropping the tank and if i cant find it then i will ask, thanks for the help.


Discretesignals
Ultimate Carjunky / Moderator
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Sep 30, 2012, 7:44 PM

Post #6 of 11 (1605 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

Maybe they will give you some extra credit too... Wink





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


sublimeaces
User

Sep 30, 2012, 9:22 PM

Post #7 of 11 (1598 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

hahaha


Tom Greenleaf
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Oct 1, 2012, 5:15 AM

Post #8 of 11 (1588 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

Quick read, sorry. Have you driven this car much with assorted known levels of fuel? Out of memory many GMs didn't buffer a fuel gauge so they could read all over the place on corners, starting out and stopping then would stabilize to some close reading.

If you can get different reading or erratic reading just sitting still that wouldn't be the issue. It's a pretty basic float not sure if cork or brass about as high tech as the float in a toilet tank,

T



sublimeaces
User

Oct 1, 2012, 1:34 PM

Post #9 of 11 (1566 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

no not the case, after a full gas tank the needle will be on empty for about a week then all of a sudden read 3/4 tank which just leads more to the bad ground idea


Hammer Time
Ultimate Carjunky / Moderator
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Oct 1, 2012, 1:47 PM

Post #10 of 11 (1563 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

No, that sounds more like a bad fuel gauge sender.



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Tom Greenleaf
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Oct 1, 2012, 2:08 PM

Post #11 of 11 (1560 views)
Re: 68 4 door chevy impala fuel sending unit Sign In

Is there just one wire going to the gauge sender at tank? Does that have good contact? I think you can get at that without removing tank and it just pushes on. If that type just take that off, clean it up as best you can and if a loose fit push on type you can just give it a "just so" squeeze with like a crimper for wire ends just enough to make it snug again.

Not sure and AYOR but if wire is off would read empty and if grounded read full with ignition in run position. AYOR as you don't want to ground it out hard or for long. If you do that test try using a test light (incandescent) as the grounding device and just for a second while a helper watches the gauge.

I don't think GM was playing the 6v gauge thing on 12v systems into the 1960s - some did. Be glad it's a Chevy as your chances of finding parts NOS are pretty good still I would bet,

T







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