fuel gauge reading wrong

[Matt L.]

i have a new fuel sending unit and gas tank installed.
before replacement the gauge would read forever full then fall to empty suddenly. and it was very near to empty when i looked into the tank.
now with the new parts it only reads a 1/4 tank when full. do i have a resistance problem here? is the gauge bad? i would like to keep the original gauge without it having a new face on it.
any advice is very appreciated.
take care,
matt

[John H.]

Re: fuel gauge reading wrong

i have a new fuel sending unit and gas tank installed.
before replacement the gauge would read forever full then fall to empty suddenly. and it was very near to empty when i looked into the tank.
now with the new parts it only reads a 1/4 tank when full. do i have a resistance problem here? is the gauge bad? i would like to keep the original gauge without it having a new face on it.
any advice is very appreciated.
take care,
matt

Matt -

Your post doesn't identify a year, but I'll assume it's the '64 in your profile. The link below will take you to a paper on diagnosing the midyear fuel gauge system, which was unique to '63-'67 and was never used again.

http://www.lbfun.com/warehouse/tech_info/gauges%20&%20instruments/MidyearFuelGauge.pdf

[Ronald L.]

Re: fuel gauge reading wrong

Matt, to cut to the chase (John's article is comprehensive and the best), last year we had this same issue and the result posted here.

Measure the resistance of you fuel sender, before you put it in the tank. Does it real 90 ohms full up?

And zero down in the empty position?

If not, like all junk from China I tried (before installation) - they would NEVER give you a proper tank reading. If you saw that set of notes and your sender measured 90 ohms resistance in the up position, your car has more issues...

Now that you have this in the tank, take and follow John's article to a T, including getting something like a wire into the tank and raising the float arm and also pushing in down to the bottom, if the tank is full.