Fuel sending unit verification question.

1618 Views 8 Replies 5 Participants Last post by tgifford5, Mar 13, 2007

tgifford5

Discussion Starter · Mar 11, 2007

I have a 69 camaro with a fuel gauge reading issue. It was reading OK, not great but OK. Then it stopped and only reads past full. I have read the posts from you whizzes and here is what I came up with and just wanted some verification. I cleaned the ground wire and surface for the sending unit. Then I disconnected the tan wire that feeds to the sending unit at the back of the trunk. With the ignition on it still reads past full. Then I disconnected and grounded the body wire and the gauge reads empty. So I am guessing that the wiring forward and the guage are good. So from all this my sending unit is bad or a broken wire on the sending unit right. And how do I know ahead of time what sending unit I have? I would like to order ahead of time before I drop the tank, 3/8ths or 5/16ths. Thanks.

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spideynut

· #2 · Mar 11, 2007

You need to measure the solid fuel line coming from your tank to find what size you have. While ypur in there check for a return line. What does your gauge do if you ground the brn sending wire?

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dale68z

· #3 · Mar 11, 2007

I have found both of my cars at one time or another 's gas gauge didnt work.
I found the problem with both was corrosion inside the sender on the stud that the sender "strap" goes to. It has apush on clip holding the strap to the stud, the clip was loose and the stud/ strap corroded, cleaned and retightened, all good.

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tgifford5

Discussion Starter · #4 · Mar 11, 2007

spideynut said:
You need to measure the solid fuel line coming from your tank to find what size you have. While ypur in there check for a return line. What does your gauge do if you ground the brn sending wire?

My guage went to empty when I grounded the brn wire coming from the guage.

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spideynut

· #5 · Mar 11, 2007

I think your correct about the sender sounds like its bad or just stuck on full. How much gas do you have in the tank? I think at this point you need to drop the tank. You can bench test the sender once its out of the tank too. If your one of those guys with an unlimited budget you could just order the sender. I went through pretty much the same thing but my sender was stuck on full once I cleaned it up I was able to get a positive bench test and just reused the sender. Its still working to this day.

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D'Z69BB

· #6 · Mar 11, 2007

my 69 fuel gauge is acting in the same manner. Only I have a new fuel tank and sending unit. I dbl checked my connections and I'm getting pwr all the way to the gauge.I can ground the gauge(I have two)and It'll go to full. I'm thinkin the sending unit as well.

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tgifford5

Discussion Starter · #7 · Mar 12, 2007

spideynut said:
I think your correct about the sender sounds like its bad or just stuck on full. How much gas do you have in the tank? I think at this point you need to drop the tank. You can bench test the sender once its out of the tank too. If your one of those guys with an unlimited budget you could just order the sender. I went through pretty much the same thing but my sender was stuck on full once I cleaned it up I was able to get a positive bench test and just reused the sender. Its still working to this day.

I don't know how much gas is in the tank. Last year I just filled it up every couple times out just so I wouldn't run out. So at this point I don't know. How long of a process is it to drop the tank? And any special instructions I should know? Spring is almost here and I want to be up and running soon.

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JimM

· #8 · Mar 12, 2007

How hard it is to drop the tank depends on how much gas is in there!!

undo the fuel line, remove the screw for the ground wire, push the sender wire and grommet thru the hole in the trunk, then take the nuts off at the back of the straps and it will basically fall out. How hard it falls, of course, depends, see above.

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tgifford5

Discussion Starter · #9 · Mar 13, 2007

JimM said:
How hard it is to drop the tank depends on how much gas is in there!!

undo the fuel line, remove the screw for the ground wire, push the sender wire and grommet thru the hole in the trunk, then take the nuts off at the back of the straps and it will basically fall out. How hard it falls, of course, depends, see above.

Nice one Jim!:thumbsup: Got the tank out after syphoning some gas out so not to drop it to hard. Cleaned up the unit and bench tested it and finally got some resistance readings. Now I have to wait to get a new tank strainer before I reinstall it as the old one was torn. The bad news though was that I didn't find a build sheet either, darn. Thanks again for all the help that I've obtained from this site. It's been great for someone such as I - a novice! :bow: :bow:

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